Sanitär- und Kommunaltechnik; Umwelttechnik
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Eingeladener Vortrag
- nein (25)
Singlet oxygen can severely damage biological tissue, which is exploited in photodynamic therapy (PDT). In PDT, the effective range is limited by the distribution of the photosensitizer (PS) and the illuminated area. However, no distinction is made between healthy and pathological tissue, which can cause undesired damage. This encouraged us to exploit the more acidic pH of cancerous tissue and design pH-controllable singlet oxygen-generating boron-dipyrromethene (BODIPY) dyes. A pH sensitivity of the dyes is achieved by the introduction of an electronically decoupled, photoinduced electron transfer (PET)-capable subunit in meso-position of the BODIPY core. To favor triplet-state formation as required for singlet Oxygen generation, iodine substituents were introduced at the chromophore core. The resulting pH-controlled singlet oxygen-generating dyes with pKa values in the physiological range were subsequently assessed regarding their potential as pH-controlled PS for PDT.
Using HeLa cells, we could successfully demonstrate markedly different pH-dependent cytotoxicities upon illumination.
Gegenstand der vorzustellenden Arbeiten ist die Prüfung der Umwelt-beständigkeit und -verträglichkeit von Materialien und Produkten hinsichtlich der Emission von potenziellen Schadstoffen in die Umwelt. Hierzu werden chemisch-physikalische Einflüsse (Bewitterung) und mikrobielle Beanspruchungen an Modellmaterialien evaluiert. So werden die Freisetzungsraten von Schadstoffen in Abhängigkeit der Beanspruchung beschrieben. Als Modellmaterialien kommen die Polymere Polystyrol (PS) und Polypropylen (PP) zum Einsatz. Synergistische Effekte der Bewitterungsparameter und der mikrobiologischen Beanspruchung sollen dabei ebenso betrachtet werden, wie die gezielte Alterung. Auch findet eine Beschreibung des Verhaltens der ausgetragenen Schadstoffe (polybromierte Flammschutzmittel) in den Umweltkompartimenten Boden oder Wasser statt. Hier sind mit Hilfe der zu entwickelnden Screening- und non-Target-Analyseverfahren die Transformation und der Metabolismus durch Mikroorganismen zu beschreiben. Aus den Ergebnissen sollen Korrelationen zwischen den künstlichen Alterungsverfahren und realen Szenarien abgeleitet werden.
Warfarin als ein Vertreter der NSO-Hetereozyklen, ist seit den 1950er Jahren einer der bekanntesten Gerinnungshemmer. Beim Menschen wird es bis heute zur Vorbeugung von Thrombose und der Behandlung von Vorhofflimmern und Arrhythmie eingesetzt. Doch schon einige Jahre vor der FDA Zulassung als Medikament wurde es zur Bekämpfung von Nagetieren eingesetzt. Bis heute wurde es nur teilweise durch weitaus wirksamere antikoagulante Rodentizide (ARs) der zweiten Generation, sogenannte Superwarfarine, ersetzt. In der Fachliteratur finden sich zahlreiche Beispiele für sekundäre und tertiäre Vergiftung mit ARs bei Wildtieren und anderen Nichtzieltieren. Bisher ist relativ wenig über die Bioakkumulation, Persistenz und Toxizität von ARs und deren Transformationsprodukten (TPs) in der terrestrischen und aquatischen Umwelt, sowie der Nahrungskette bekannt.
Um Einblicke in mögliche Transformations- und Abbauprozesse von Warfarin zu erhalten und um Umwelteinflüsse zu simulieren, wurde es in einer elektrochemischen Reaktorzelle oxidativ umgesetzt und mittels Massenspektrometrie analysiert. Hinsichtlich der Wasseraufbereitung in Kläranlagen wurden technisch relevante Simulationsverfahren wie Chlorung, UV-Bestrahlung und Ozonung angewendet um potentielle Eliminierungswege aufzuklären. Gebildete Transformationsprodukte wurden daher mittels unterschiedlicher chromatografischer Verfahren getrennt, massenspektrometrisch analysiert und verglichen.
Separation and detection of antioxidants using a graphene based electrochemical sensor platform
(2019)
CVD-Graphene is ideally suited as an active element for electrical and electrochemical sensing platforms, since it provides for high sensitivity and low detection limit. Electrochemical sensors provide a simple way to measure analytes in fluids with high sensitivity without the need for complex instrumentation. Due to These aspects, graphene sensors are interesting for a wide range of applications in bio analytics. Antioxidants are natural or synthetic compounds, which inhibit oxidation processes and hence often find use as preservatives.
It has been suggested that the long-term consumption of diets rich in antioxidants is associated with a lower risk of developing diseases linked to oxidative stress. Gallic acid and ascorbic acid are representatives of antioxidants. We have developed a graphene-based sensor platform to separate and subsequently detect antioxidants. Graphene exhibits low detection limits for ascorbic acid and polyphenols. In this study, the sensing of gallic acid and ascorbic acid on bare CVD graphene in various solvents was investigated by Square Wave Voltammetry. Furthermore, the separation and detection of the bioanalytes by deploying different membranes were evaluated.
Background. Aflatoxin B1 (AFB1) is a toxic low-molecular-weight secondary fungal metabolite produced mainly by Aspergillus flavus and Aspergillus parasiticus not only at pre-harvest time but also at post-harvest stages including storage. AFB1 was classified as a Group I carcinogen by the World Health Organization for Research on Cancer in 1993. AFB1 is able to naturally contaminate medicinal plants and therefore causing serious health issues for humans consuming the related medicine. This study aimed to develop an efficient fluorescence polarization immunoassay (FPIA) and for the first time a rapid (5-10 min), low-cost, and simple membrane-based flow-through immunoassay (MBA) for determination of AFB1 in medical herbs based on a monoclonal antibody.
Methods. Two different techniques for AFB1detection in medical herbs (Herba Orígani vulgáris, Folia Urticae, Fructus Rubi idaei) were developed and compared, namely an easy-to-use semi-quantitative flow-through membrane-based enzyme immunoassay (MBA), and a homogeneous method which needs no separation or washing steps (assay time 10 min), a quantitative fluorescence polarization immunoassay (FPIA).
Results. A cut-off level of the developed MBA can vary wide from 0.8 ppb to 1 ppb. The FPIA method showed a linear working range of 8.6 ppb to 64 ppb, IC50 of FPIA is 24 ppb. The results were in good correlation with the ELISA results (IC50 = 0.1 ppb). LC–MS/MS was used to confirm the results, too.
Conclusion. MBA can be used for a quick on-site AFB1 detection in medical herbs (Herba Orígani vulgáris (Oríganum vulgáre), Folia Urticae (Urtíca dióica), Fructus Rubi idaei (Rúbus idáeus)), the developed test does not require special equipment and is not time-consuming (5-10min), includes several simple steps and can be performed directly on-site. The major advantages of the developed FPIA are its simplicity and suitability for a rapid screening of a large number of samples.
Die vom BMBF unterstütze Forschungsinitiative BonaRes entwickelt Strategien um Boden als nachhaltige Ressource für die Bioökonomie zu nutzen. Das Projekt Intelligence for Soil (I4S) ist ein Teil dieser Initiative und beschäftigt sich mit der Entwicklung eines integrierten Systems zur ortsspezifischen Düngung. Ein Ziel dieses Projektes ist die Etablierung einer mobilen Sensorplattform zur Bodenkartierung. Aufgabe der BAM ist dabei das Installieren und die Optimierung eines RFA Sensors für die online Messung direkt auf dem Feld. Die RFA ist eine zerstörungsfreie Technik, die kaum Probenvorbereitung benötigt und einen schnelle Multielement Analyse ermöglicht. Das schnelle Kartieren des Bodens ermöglicht später eine ortsspezifische Düngung mit Nährstoffen wie z.B. K, Ca und P.
Die vom BMBF unterstütze Forschungsinitiative BonaRes entwickelt Strategien um Boden als nachhaltige Ressource für die Bioökonomie zu nutzen. Das Projekt Intelligence for Soil (I4S) ist ein Teil dieser Initiative und beschäftigt sich mit der Entwicklung eines integrierten Systems zur ortsspezifischen Düngung. Ein Ziel dieses Projektes ist die Etablierung einer mobilen Sensorplattform zur Bodenkartierung. Aufgabe der BAM ist dabei das Installieren und die Optimierung eines RFA Sensors für die online Messung direkt auf dem Feld. Die RFA ist eine zerstörungsfreie Technik, die kaum Probenvorbereitung benötigt und einen schnelle Multielement Analyse ermöglicht. Das schnelle Kartieren des Bodens ermöglicht später eine ortsspezifische Düngung mit Nährstoffen wie z.B. K, Ca und P.
Within the framework of precision agriculture, the determination of various soil properties is moving into focus, especially the demand for sensors suitable for in-situ measurements. Energy-dispersive X-ray fluorescence (EDXRF) can be a powerful tool for this purpose. In this study a huge diverse soil set (n = 598) from 12 different study sites in Germany was analysed with EDXRF. First, a principal component analysis (PCA) was performed to identify possible similarities among the sample set.
Clustering was observed within the four texture classes clay, loam, silt and sand, as clay samples contain high and sandy soils low iron mass fractions. Furthermore, the potential of uni- and multivariate data evaluation with partial least squares regression (PLSR) was assessed for accurate Determination of nutrients in German agricultural samples using two calibration sample sets. Potassium and iron were chosen for testing the performance of both models. Prediction of these nutrients in 598 German soil samples with EDXRF was more accurate using PLSR which is confirmed by a better overall averaged deviation and PLSR should therefore be preferred.
Antifoulingmittel im Wasser
(2019)
Zu den letzten beiden Jahrestagungen der GUS wurden Verfahren und Methoden vorgestellt, die es gestatten, den Transfer von Schadstoffen aus Materialien und Produkten in die Umwelt unter umweltrelevanten Bedingungen beschreiben zu können. Dabei lag der Fokus auf den Materialien und der eingesetzten Umweltsimulationen. In einem sich anschließenden Schritt soll nun das Verhalten der freigesetzten organischen Schadstoffe unter den Bedingungen von realen und simulierten Umwelteinflüssen charakterisiert und beschrieben werden. Hier werden im Detail drei potentielle Schadstoffe betrachtet, die Inhaltsstoffe bzw. Additive in den jeweils eingesetzten Materialien sind. Im Falle von Polypropylen (PP) und Polystyrol (PS) handelt es sich um polybromierte Flammschutzmittel BDE 209 (Decabrom-diphenylether, als Einzelsubstanz) und HBCD (Hexabromcyclododecan, als technische Formulierung). Für das eingesetzte Polycarbonat ist BPA (Bisphenol A) als Schadstoff zu definieren, welcher unter umweltrelevanten Bedingungen freigesetzt wird. Im Rahmen der durchzuführenden Arbeiten sollen die aufgeführten prioritären Schadstoffe hinsichtlich möglicher Transformationsprozesse in Umwelt und Klärwerk charakterisiert werden. Die unter den Bedingungen der Ozonung, Chlorierung und UV-Bestrahlung erhaltenen Transformationsprodukte (TPs) sollen im Sinne einer Non-Target-Analytik identifiziert und eindeutig charakterisiert werden. Die Ergebnisse sollen mittels vorhandener Analysenverfahren, wie GC-EI-MS, HPLC-ESI-IT-MSn bzw. LC-MS/MS erzeugt bzw. abgesichert werden. Anhand der in der Struktur eindeutig zu beschreibenden Transformationsprodukte und der Charakterisierung von potentiellen Intermediaten sollen belastbare Reaktionswege und –mechanismen abgeleitet werden.
In addition to previously reported results on the accelerated weathering of polystyrene samples (PS) containing 1 wt.% hexabromocyclododecane (HBCD), we present the first results of our investigations of polypropylene samples (PP) containing 0.1 wt.% BDE-209. All studied polymer samples were exposed to a defined weathering schedule in a climate chamber in accordance to regulation EN ISO 4892-3:2006. For the determination of BDE-209 in the collected raining water the samples were prepared in accordance to a validated protocol. Before the analyses each sample was spiked with isotopically labeled BDE-209. Subsequently the samples were extracted with isooctane. The obtained extracts were concentrated, and the resulting solutions were analyzed by GC/MS. Additionally, the total bromine content was monitored for the weathered and untreated samples using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and X-ray fluorescence analysis (XRF) as a non-destructive and rapid method. In general, the resulting data from the accelerated weathering will be compared to those from the natural weathering experiments. Here, the surfaces of the test pieces were analyzed by LA-ICP-MS and XRF as well. Moreover, soil bed tests were conducted in a well characterized model soil. This soil (boulder-clay, sand with 12 % loam, particle size in total 0.2-4 mm) is filled in a free-draining basin inside of an air-conditioned cellar. In this manner, TOC, water capacity and humidity are recorded parameters. To induce a leaching process from the samples by the raining water, the target water content is calculated to 8%. The actual humidity is measured by a tensiometer, assuring the duration of the raining period. A defined humidity is a fundamental parameter for a biological activity in the soil. The test polymers were placed up to the half in the soil. Microbial activity of the soil is monitored by a reference polymer (polyurethane) and should induce the release of HBCD and BDE-209 out of the test materials. These released analytes will be captured by passive samplers (silicone tubes) placed in a distinct distance to the polymer samples in the soil. The soil bed experiments are complementary to the weathering experiments due to the biological activity in the soil.
In addition to previously reported results on the accelerated weathering of polystyrene samples (PS) containing 1 wt.% hexabromocyclododecane (HBCD), we present the first results of our investigations of polypropylene samples (PP) containing 0.1 wt.% BDE-209. All studied polymer samples were exposed to a defined weathering schedule in a climate chamber in accordance to regulation EN ISO 4892-3:2006. For the determination of BDE-209 in the collected raining water the samples were prepared in accordance to a validated protocol. Before the analyses each sample was spiked with isotopically labeled BDE-209. Subsequently the samples were extracted with isooctane. The obtained extracts were concentrated, and the resulting solutions were analyzed by GC/MS. Additionally, the total bromine content was monitored for the weathered and untreated samples using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and X-ray fluorescence analysis (XRF) as a non-destructive and rapid method. In general, the resulting data from the accelerated weathering will be compared to those from the natural weathering experiments. Here, the surfaces of the test pieces were analyzed by LA-ICP-MS and XRF as well. Moreover, soil bed tests were conducted in a well characterized model soil. This soil (boulder-clay, sand with 12 % loam, particle size in total 0.2-4 mm) is filled in a free-draining basin inside of an air-conditioned cellar. In this manner, TOC, water capacity and humidity are recorded parameters. To induce a leaching process from the samples by the raining water, the target water content is calculated to 8%. The actual humidity is measured by a tensiometer, assuring the duration of the raining period. A defined humidity is a fundamental parameter for a biological activity in the soil. The test polymers were placed up to the half in the soil. Microbial activity of the soil is monitored by a reference polymer (polyurethane) and should induce the release of HBCD and BDE-209 out of the test materials. These released analytes will be captured by passive samplers (silicone tubes) placed in a distinct distance to the polymer samples in the soil. The soil bed experiments are complementary to the weathering experiments due to the biological activity in the soil.
Warfarin, also known as Coumadin is one of the most popular anticoagulant drugs used as a therapeutic in humans to prevent thrombosis, atrial fibrosis, and fibrillation since the 1950s. Because of its ability to hinder blood from clotting by blocking vitamin K-depending carboxylation of blood clotting precursors, it is also used as a rodenticide worldwide. Until today it has been partially substituted by far more potent anticoagulant rodenticides (ARs), so-called superwarfarins. There are numerous references confirming secondary and tertiary poisoning in non-target-animals and wildlife like mammals, birds, and fish associated with ARs. Up to now relatively little is known about persistence and toxicity of transformation products of those AR in the environment and food chain. Herein, warfarin was chosen as a model compound to determine andelucidate TPs which are generated technically and under environment-like conditions. Such as the simulation of the oxidative phase I metabolism by implementing electrochemical flow cells coupled to mass spectrometry (MS). Obtained results are being compared to TPs generated by UVB-irradiation and ozonation.
Analysis and separation of degradation products and TPs were achieved by a variety of gas- and liquid chromatographic techniques coupled to (high resolution) MS.
Environmental sustainability and –stability of materials concerning the migration of pollutants
(2019)
In addition to previously reported results on the accelerated weathering of polystyrene samples (PS) containing 1 wt. % hexabromocyclododecane (HBCD), we present the first results of our investigations of polypropylene samples (PP) containing 0.1 wt. % BDE-209. All studied polymer samples were exposed to a defined weathering schedule in a climate chamber in accordance to regulation EN ISO 4892-3:2006. For the determination of BDE-209 in the collected raining water the samples were prepared in accordance to a validated protocol. Before the analyses each sample was spiked with isotopically labeled BDE-209. Subsequently the samples were extracted with isooctane. The obtained extracts were concentrated, and the resulting solutions were analyzed by GC/MS. Additionally, the total bromine content was monitored for the weathered and untreated samples using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and X-ray fluorescence analysis (XRF) as a non-destructive and rapid method. In general, the resulting data from the accelerated weathering will be compared to those from the natural weathering experiments. Here, the surfaces of the test pieces were analyzed by LA-ICP-MS and XRF as well. Moreover, soil bed tests were conducted in a well characterized model soil. This soil (boulder-clay, sand with 12 % loam, particle size in total 0.2-4 mm) is filled in a free-draining basin inside of an air-conditioned cellar. In this manner, TOC, water capacity and humidity are recorded parameters. To induce a leaching process from the samples by the raining water, the target water content is calculated to 8%. The actual humidity is measured by a tensiometer, assuring the duration of the raining period. A defined humidity is a fundamental parameter for a biological activity in the soil. The test polymers were placed up to the half in the soil. Microbial activity of the soil is monitored by a reference polymer (polyurethane) and should induce the release of HBCD and BDE-209 out of the test materials. These released analytes will be captured by passive samplers (silicone tubes) placed in a distinct distance to the polymer samples in the soil. The soil bed experiments are complementary to the weathering experiments due to the biological activity in the soil.
Elementanalytische Verfahren werden heute zu mehr eingesetzt als bloß zur Bestimmung von Metallgesamtgehalten in diversen Probenmatrizes. Sie stellen heute ein wichtiges Werkzeug zur Beantwortung lebenswissenschaftlicher Fragen aus Umwelt, Medizin und Biologie dar. In der vorliegenden Arbeit kommt die single-cell-ICP-Flugzeitmassenspektrometrie (single-cell-ICP-TOF-MS) zur Multielementanalytik in einzelnen Kieselalgen (Diatomeen) zum Einsatz und wird zukünftig ein wichtiges Werkzeug z.B. bei der Beantwortung
ökotoxikologischer Fragestellung sein.
In den vergangen Jahren hat das Umweltbewusstsein in der Bevölkerung stark zugenommen und somit auch das Interesse an der Vermeidung von anthropogenen (Schad-)Stoffen in der Umwelt. Eine (neue) Substanzklasse, deren Umweltauswirkungen noch nicht vollständig untersucht sind und die in den vergangenen Jahren immer mehr an Bedeutung gewonnen hat, sind (metallbasierte) Nanomaterialien. Im Gegensatz zu bspw. Elementspezies weisen Nanomaterialien eine Vielzahl von Eigenschaften auf und lassen sich nicht über nur ein Merkmal beschreiben - dies stellt eine große analytische Herausforderung dar. Hier haben sich vor allem die Feld-Fluss-Fraktionierung (AF4) und die single-particle-ICP-MS als leistungsstarke analytische Methoden herausgestellt. In (aquatischen) Umweltmatrizes (z.B. Oberflächengewässern) liegen neben artifiziellen auch natürliche Partikel vor, was eine weitere große Herausforderung für den Nachweis von Nanomaterialien darstellt.
Neben dem Nachweis von anthropogenen Stoffen in der Umwelt ist zudem deren ökotoxikologische Bewertung wichtig. In der aquatischen Ökotoxikologie werden hierzu Testorganismen mit den jeweiligen Substanzen über die Wasserphase exponiert. Effektkonzentrationen (EC50) werden dabei auf Basis der Konzentrationen in der Wasserphase abgeleitet - tatsächlich bioakkumulierte Mengen werden hierbei jedoch meist nicht ermittelt; eine weitere große Herausforderung besteht zudem in der Bewertung von Mischungstoxizitäten. Gängige Testorganismen sind u.a. Kieselalgen (Diatomeen). Diatomeen stehen am Anfang der Nahrungskette - toxikologisch relevante Metalle/Nanomaterialien können sich hierüber im Nahrungsnetz der Oberflächengewässer anreichern und ggf. nachhaltig auswirken.
Im ersten Teil des Vortrages werden zunächst neue elementanalytische Methoden zum Nachweis von metallbasierten Nanopartikeln in Umweltmatrizes auf Basis der AF4/ICP-SFMS sowie stabilen Isotopenlabeln am Beispiel von Eisennanopartikeln vorgestellt.
Im zweiten Teil wird eine neue elementanalytische Methode als komplementäre Technik zur ökotoxikologischen Bewertung von (Schad-)Stoffen vorgestellt. Die neue Methode basiert auf der on-line Kopplung von HPLC mit der single-cell-ICP-(ToF)-MS (sc-ICP-(ToF)-MS) [1, 3-5]. Hierüber konnten wir erfolgreich die automatisierte Multielementanalytik einzelner Diatomeen realisieren und zur Analyse von mit Metallen inkubierten Diatomeen (cyclotella meneghiniana) einsetzen. Wir konnten zeigen, dass die sc-ICP-ToF-MS zukünftig eine leistungsstarke, komplementäre Technik in der aquatischen Ökotoxikologie zum z.B. Test von Metallen und Nanomaterialien darstellt.
Monitoring programs should generate high-quality data on the concentrations of substances and other pollutants in the aquatic environment to enable reliable risk assessment. Furthermore, the need for comparability over space and time is critical for analysis of trends and evaluation of restoration of natural environment. Additionally, research work and exercises at the European level have highlighted that reliable measurements of estrogenic substances at the PNEC level are still challenging to achieve. The project EDC-WFD “Metrology for monitoring endocrine disrupting compounds under the EU Water Framework Directive” aims to develop traceable analytical methods for determining endocrine disrupting compounds and their effects, with a specific focus on three estrogens of the first watch list (17-beta-estradiol (17βE2), 17-alpha-ethinylestradiol (EE2), and estrone (E1)). Estrogens 17-alpha-estradiol (17aE2) and estriol (E3) will be included to demonstrate the reliability of the developed methods - Mass Spectrometry based method and effect-based methods (EBM) - and to support the requirements of Directive 2013/39/EC, Directive 2009/90/EC and Commission Implementation Decision (EU) 2018/840, hence improving the comparability and compatibility of measurement results within Europe. During the EDC-WFD project four EBM will be deeply investigated in order to improve their rationale use and their support in water quality assessment.
Monitoring programs should generate high-quality data on the concentrations of substances and other pollutants in the aquatic environment to enable reliable risk assessment. Furthermore, the need for comparability over space and time is critical for analysis of trends and evaluation of restoration of natural environment. Additionally, research work and exercises at the European level have highlighted that reliable measurements of estrogenic substances at the PNEC level are still challenging to achieve. The project EDC-WFD “Metrology for monitoring endocrine disrupting compounds under the EU Water Framework Directive” aims to develop traceable analytical methods for determining endocrine disrupting compounds and their effects, with a specific focus on three estrogens of the first watch list (17-beta-estradiol (17βE2), 17-alpha-ethinylestradiol (EE2), and estrone (E1)). Estrogens 17-alpha-estradiol (17aE2) and estriol (E3) will be included to demonstrate the reliability of the developed methods - Mass Spectrometry based method and effect-based methods (EBM) - and to support the requirements of Directive 2013/39/EC, Directive 2009/90/EC and Commission Implementation Decision (EU) 2018/840, hence improving the comparability and compatibility of measurement results within Europe. During the EDC-WFD project four EBM will be deeply investigated in order to improve their rationale use and their support in water quality assessment.
Monitoring programs should generate high-quality data on the concentrations of substances and other pollutants in the aquatic environment to enable reliable risk assessment. Furthermore, the need for comparability over space and time is critical for analysis of trends and evaluation of restoration of natural environment. Additionally, research work and exercises at the European level have highlighted that reliable measurements of estrogenic substances at the PNEC level are still challenging to achieve. The project EDC-WFD “Metrology for monitoring endocrine disrupting compounds under the EU Water Framework Directive” aims to develop traceable analytical methods for determining endocrine disrupting compounds and their effects, with a specific focus on three estrogens of the first watch list (17-beta-estradiol (17βE2), 17-alpha-ethinylestradiol (EE2), and estrone (E1)). Estrogens 17-alpha-estradiol (17aE2) and estriol (E3) will be included to demonstrate the reliability of the developed methods - Mass Spectrometry based method and effect-based methods (EBM) - and to support the requirements of Directive 2013/39/EC, Directive 2009/90/EC and Commission Implementation Decision (EU) 2018/840, hence improving the comparability and compatibility of measurement results within Europe. During the EDC-WFD project four EBM will be deeply investigated in order to improve their rationale use and their support in water quality assessment.
Ein Vergleich der Gehalte von Difluoressigsäure (DFA) und Trifluoressigsäure (TFA) in Regen- und Oberflächenwässern im Berliner Raum ergab ein TFA/DFA Verhältnis in Regenwasser von 10:1. Im Gegensatz dazu wies Grundwasser aus dem Einzugsbereich einer historischen Kontamination durch Fluorchlorkohlenwasserstoffe (FCKW) ein TFA/DFA-Verhältnis von 1:3 auf. Dies und die ungewöhnlich hohe DFA-Konzentration an dieser Stelle wird vor dem Hintergrund der beobachteten mikrobiellen Abbauprodukte des ursprünglichen eingetragenen FCKW 1,1,2-Trichlor-1,2,2-trifluorethan (R113) diskutiert. Eine mikrobielle Umwandlung des bekannten Abbauproduktes Chlortrifluorethylen (R1113) zur DFA wurde bislang nicht in Umweltkompartimenten beobachtet und wird hier auf Basis bekannter Stoffwechselwege vorgeschlagen.
TFA wurde in Regenwasser, Oberflächenwasser und Grundwasser in vergleichbaren Größenordnungen von ca. 500 ng/L bestimmt. Im Gegensatz dazu wurde DFA in Grundwasserproben im Bereich der Schadstoffquelle der FCKW-Kontamination mit bis zu 2.000 ng/L nachgewiesen. Die Summe von TFA und DFA im Grundwasser korreliert nicht mit dem Eintrag aus Niederschlag und Oberflächenwasser. Darum liegt die Vermutung nahe, dass es für DFA andere Quellen als den direkten Eintrag oder den möglichen Abbauweg über TFA geben muss. DFA ist vermutlich ein Abbauprodukt von R1113. FCKWs, die im ersten Abbauschritt zu 1,1-Difluorethenen metabolisieren, stehen im Verdacht, in der Folge zu DFA zu hydrolysieren. Entscheidend scheint, dass bereits im Ausgangsprodukt ein CF2-Strukturelement enthalten ist, das dann zur Bildung von DFA führen kann. Somit würde aus dem ursprünglichen Eintrag des Kältemittels R113 über schrittweise Dechlorierung via 1,2-Dichlor-1,2,2-Trifluorethan (R123a) und R1113 die Bildung des beobachteten DFA folgen. Es ist also sinnvoll, DFA in die Diskussion zur Regulierung der Endprodukte des Abbaus fluorhaltiger Kälte- oder Lösungsmittel einzubeziehen. Die Ergebnisse wurden im Normausschuss Wasserwesen (NAW) des DIN vorgestellt und es soll ein Arbeitskreis gegründet werden, der ein Normverfahren zur Quantifizierung von TFA und DFA in Wasser erarbeitet. Interessierte Laboratorien sind herzlich eingeladen, die Normungsarbeit zu unterstützen.
Regardless of its ban in agricultural use, the triazine derivative terbutryn is still used as a biocide against biofouling in building materials, such as façade colors and roof tiles. From there, it is washed off and may contaminate soil and surface waters, where it shows ecotoxicological behavior. For understanding of these leaching processes, analytical methods that can detect terbutryn in traces are necessary. In contrast to separation methods (Gas (GC) or liquid chromatography (LC)) coupled to mass spectrometry (MS), enzyme immunoassays (EIAs) have proven to be adequate tools for environmental monitoring. Compared to GC-or LC-MS, they are cheap, require only limited time and experimental expertise and enable high throughput. For quantification of terbutryn, EIAs have been established, with a limit of detection (LOD) of 50 ng L-1. For leaching experiments however, a lower LOD would be advantageous.
For detection of terbutryn we developed a direct competitive ELISA based on a monoclonal antibody: Terbutryn and an enzyme-terbutryn conjugate (“tracer”) compete for the binding sites of the immobilized antibody. The bound tracer converts a colourless substrate into a blue-coloured product, which can be detected via spectrophotometry. For quantification of terbutryn, a sigmoidal calibration curve is used. For establishing of the EIA, a new tracer based on a terbutryn surrogate (“hapten”) was synthesized. After optimization of the experimental conditions, the immunoassay exhibited a more than ten-fold increased sensitivity (LOD: 3 ng L-1), high stability against sample compounds (Ca2+, NaCl) and lower cross-reactivities against structurally related compounds, than reported before. Analysis of spiked samples was possible with high precision (inter-assay CV: < 10 %) and accuracy (recoveries from spiked samples: 89 % ± 10%). We therefore propose it as quick and reliable method for leaching studies of terbutryn out of building materials.
Neuartige Materialien, die bekannte (Werk-)Stoffe mit neuen Funktionalitäten ausstatten, spielen eine zunehmend wichtige Rolle im Bereich der Materialforschung und -prüfung. Das Spektrum neuartiger Materialien reicht von der gezielten Oberflächenfunktionalisierung und -strukturierung makroskopischer Materialien, dünnen Beschichtungen bis hin zu mikro- und nanoskaligen Kompositmaterialien und funktionalen Materialien an der Schnittstelle zur Biologie, Biotechnologie, nachhaltige Energiespeicherung und Sensorik. Dabei bieten neuartige Materialien die Chance, Werkstoffe und Produkte mit erweiterter oder verbesserter Funktionalität zu erhalten und Sicherheit bereits im Designprozess zu berücksichtigen. Durch dieses breite Anwendungsspektrum und die Herausforderungen, die solche Materialien für die Sicherheit in Chemie und Technik mit sich bringen, sind diese in allen Themenfeldern der BAM repräsentiert (Material, Analytical Sciences, Energie, Infrastruktur und Umwelt).
Die Aufgaben der BAM erstrecken sich dabei von der Herstellung von Referenzmaterialien für Industrie, Forschung und Regulation, über die Erstellung von standardisierten Referenzverfahren für nachhaltige Messungen im Umwelt- und Lebenswissenschaftsbereich bis hin zur Bereitstellung von belastbaren und zitierbaren Referenzdaten. Durch die genaue Charakterisierung neuartiger Materialien können potentiell problematische Substanzen identifiziert und deren Risiken besser abgeschätzt werden. In diesem Beitrag werden einige aktuelle Beispiele aus diesen Bereichen vorgestellt.
Herein we present the data for a newly developed immunoassay for the determination of amoxicillin (AMX) in water samples using a commercially available monoclonal anti-AMX antibody. During optimization and testing of the assay, we observed a significant decrease of the C-value (IC50) of the ELISA calibration curves with aged standard solutions. Running the assay with standard solutions of synthesized AMX hydrolysis products revealed that this decreased C-value could be attributed mainly to the hydrolysis product amoxicilloic acid. Therefore, the limit of detection of the ELISA for AMX determination in water could be enhanced by either hydrolyzing the samples or testing for amoxicilloic acid as marker substance.
The need for sustainable and effective usage of limited resources like water and soil becomes more and more important due to increasing populations and their need for food. The research initiative BonaRes funded by the Federal Ministry of Education and Research, develops strategies to use soil as a sustainable resource for the bio-economy. One part of this initiative is the Intelligence for soil (I4S) project. It deals with the development of an integrated system for the site-specific soil fertility management. The goal of the project is to establish a mobile sensor platform for soil mapping as well as to apply soil and crop models to deal with the high amount of produced data. These models are going to be used to formulate recommendations on the use of fertilizers and to gain an improvement on the soil fertility. Using these information’s, the environmental pollution with substances like nitrate contained in fertilizers can be decreased. Furthermore, the costs for farmers can be decreased if only the amounts of fertilizer actually needed are applied to the field.
The task for the Federal Institute for Materials Research and Testing (BAM) is the installation and optimization of a handheld XRF sensor for the online measurement directly on the field. It is a non-destructive technique and quite suitable for the online approach due to a low maintenance in the sample preparation and a fast and simultaneous multi element analysis. The elements of interest in this case are light elements like phosphorus, calcium and potassium. One of the major tasks is the calibration of the sensor for different soils, therefore, calibration models are evolved to deal with different types of soil. Due to the multi element analysis, micro and macro nutrients can be determined simultaneously. Those differ a lot in their contents which makes it inevitable to optimize and adapt the measuring procedure. By analyzing soil, its always important to deal with matrix effects, that is why the influence of different disturbances like the moisturize content and the grain size needs to be investigated.
The XRF is only one of many sensors that combined give customized fertilizing recommendations in the end.
The need for sustainable and effective usage of limited resources like water and soil becomes more and more important due to increasing populations and their need for food. The research initiative BonaRes funded by the Federal Ministry of Education and Research, develops strategies to use soil as a sustainable resource for the bio-economy. One part of this initiative is the Intelligence for Soil (I4S) project. It deals with the development of an integrated system for the site-specific soil fertility management. The goal of the project is to establish a mobile sensor platform for soil mapping as well as to apply soil and crop models to deal with the high amount of produced data. These models are going to be used to formulate recommendations on the use of fertilizers and to gain an improvement on the soil fertility. Using this information, the environmental pollution with substances like nitrate contained in fertilizers can be decreased. Furthermore, the costs for farmers can be decreased if only the amounts of fertilizer needed are applied to the field.
The task for BAM is installation and optimization of a handheld XRF sensor for online measurement directly on the field. It is a non-destructive technique and quite suitable for an online approach due to a low maintenance in sample preparation and a fast and simultaneous multi element analysis. The elements of interest in this case are light elements like phosphorus, calcium, and potassium. One of the major tasks is the calibration of the sensor for different soils is finding suitable calibration models, which are evolved to deal with different types of soil. Due to the multi element analysis, micro and macro nutrients can be determined simultaneously. Those differ a lot in their contents, which makes it inevitable to optimize and adapt the analytical procedure. By analyzing soil it is always important to deal with matrix effects, that is why the influence of different disturbances like the moisturize content and the grain size needs to be investigated. The XRF is only one of many sensors that combined give customized fertilizing recommendations in the end.
This paper describes the development of a semi-automatic gas measurement device presenting potentially a broad range of applications, noteworthy in the agricultural sector. Non-reversible fluorescent molecular sensors were designed and syn-thesized. Upon, integration into a hydrogel matrix with an optimal ratio of co-solvents, the sensors reacting selectively to ammonia were illuminated by excitation light to produce a concentration-correlated fluorescence emission. An automated mechanical-elec-trical device initiates a given gas mixture and thus simulates con-centrations similar to a threshold value. The aim of this project is to develop a sensor or a low-cost method which can monitor low concentrations of harmful gases and aid in their elimination or regulation in livestock housing, barns or stables.
This paper describes the development of a semi-automatic gas measurement device presenting potentially a broad range of applications, noteworthy in the agricultural sector. Non-reversible fluorescent molecular sensors were designed and syn-thesized. Upon, integration into a hydrogel matrix with an optimal ratio of co-solvents, the sensors reacting selectively to ammonia were illuminated by excitation light to produce a concentration-correlated fluorescence emission. An automated mechanical-elec-trical device initiates a given gas mixture and thus simulates con-centrations similar to a threshold value. The aim of this project is to develop a sensor or a low-cost method which can monitor low concentrations of harmful gases and aid in their elimination or regulation in livestock housing, barns or stables.
Chlorination procedures are commonly applied in swimming pool water and wastewater treatment, yet also in food, pharmaceutical, and paper production. The amount of chlorine in water needs to be strictly controlled to ensure efficient killing of pathogens but avoid the induction of negative health effects. Miniaturized microfluidic fluorescence sensors are an appealing approach here when aiming at online or at-site measurements. Two meso-enamine-substituted boron dipyrromethene (BODIPY) dyes were found to exhibit favorable indication properties, their reaction with hypochlorite leading to strong fluorescence enhancement. Real-time assays became possible after integration of these fluorescent probes with designed two-dimensional (2D) and three-dimensional (3D) microfluidic chips, incorporating a passive sinusoidal mixer and a microhydrocyclone, respectively. A comparison of the two microfluidic systems, including their abilities to prevent accumulation or circulation of microbubbles produced by the chemical indication reaction, showed excellent fluidic behavior for the microhydrocyclone-based device. After coupling to a miniaturized optical reader for fluorescence detection, the 2D microfluidic system showed a promising detection range of 0.04−0.5 mg L−1 while still being prone to bubble-induced fluctuations and suffering from considerably low signal gain. The microhydrocyclone-based system was distinctly more robust against gas bubbles, showed a higher signal gain, and allowed us to halve the limit of detection to 0.02 mg L−1. The use of the 3D system to quantify the chlorine content of swimming pool water samples for sensitive and quantitative chlorine monitoring was demonstrated.
Spectral encoding of cells or particles and the discrimination of multiple spectral codes are a critical process in flow cytometry (FCM). Typical issues in spectral encoding are, e.g., the spectral overlap of codes, or the increasing complexity of instruments . The exploitation of the photoluminescence lifetime (LT) as an encoding parameter could be used to circumvent both of these issues, as it adds another dimension to the parameter space, or, when used as a stand-alone parameter, requiring only one excitation light source and one detector. While LT encoding was considered already decades ago it is still not implemented as a routine technique in FCM yet, mainly due to the challenge of very few photons being available within the limited transition time of a cell or particle through the laser spot.
Recently, we demonstrated LT-FCM based on luminophores with ns LTs in a compact and low-cost flow cytometer. Measurements on polymer microbeads containing luminophores with distinctly different excited state LTs enabled the complete discrimination of three LT codes and five codes in total could be identified.
Now, we have extended our approach towards considerably longer LTs by custom-made polymer microbeads loaded with different ratios of InP/ZnS and AgInS2 quantum dots. The use of these materials significantly expands the usable time range for LT encoding to up to several hundred ns. Our studies demonstrate the possibility to further increase the number of viable LT codes for multiplexing in LT-FCM without the need for extensive hardware modifications.
The comparison of different emitter classes and the rational design of the next generation of molecular and nanoscale reporters require accurate and quantitative photo-luminescence measurements. This is of special importance for all photoluminescence applications in the life and material sciences and nanobiophotonics. In the following, procedures for the determination of the spectroscopic key parameter photoluminescence quantum yield, i.e., the number of emitted per absorbed photons, in the UV/vis/NIR/SWIR are presented including pitfalls and achievable uncertainties and material-specific effects related to certain emitter classes are addressed.
Luminescent nanocrystals like core/shell semiconductor quantum dots and lanthanide doped nanophosphors as well as gold nanoclusters with emission in the visible (vis) and particularly in the near infrared (NIR) and short wavelength infrared (SWIR) region have been increasingly used as reporters in the life sciences and for bioimaging studies in the last years. This has led to sophisticated core-shell particle architectures of different chemical composition utilizing semiconductor quantum dots and lanthanide-based nanocrystals and initiated the design of gold nanoclusters with different ligands. In addition, this led to an increasing number of quantitative spectroscopic studies focusing on the key performance parameter photoluminescence quantum yield to identify optimum particle structures. In the following, an overview of different classes of nanocrystalline emitters and their photophysics is provided and examples for the absolute characterization of the photoluminescence properties of these different vis/NIR/SWIR emitters are shown including excitation power density-dependent studies on the ensemble and single particle level. Also, the impact of such measurements on a profound mechanistic understanding of the underlying nonradiative deactivation pathways is highlighted as required for reporter design.
Photoluminescence applications in the life and material sciences require bright molecular and nanocrystalline emitters, stimuli-responsive optical probes, signal enhancement, multiplexing, and barcoding strategies and traceable methods to quantify the signal-relevant optical properties of luminescent materials at the ensemble and single molecule/particle level. In this context, current research at Division Biophotonics of BAM is presented ranging from dye and nanocrystal photophysics, absolute measurements of photoluminescence quantum yields in the UV/vis/NIR/SWIR, lifetime multiplexing, and the development of different types of fluorescence standards for validating optical-spectroscopic measurements.
Herein, we present the development of a gas chromatographic method for Determination of warfarin, its TPs, and selected metabolites.
TPs were formed by applying UV-irradiation, ozonation, and an electrochemical cell coupled to mass spectrometry to mimic the oxidative phase I metabolism. The further aim is to use this method for detection and quantification under environmentally relevant conditions, as well as, toxicological assessment.
Pharmaceuticals, certain food ingredients, and mammalian endogenous metabolic products in wastewater are mostly of human origin. They are anthropogenic markers.
Proper knowledge of their levels in wastewater helps to track sources of pollutants in natural waters and allows for calculation of removal efficiencies in wastewater Treatment plants. Here, we describe the development and application of an indirect competitive, multiplexing suspension Array fluorescence immunoassay (SAFIA) for the detection of carbamazepine (CBZ), diclofenac (DCF), caffeine (CAF), and isolithocholic acid (ILA) in wastewater, covering those classes of anthropogenic markers. The assay consists of haptens covalently conjugated to fluorescence-encoded polystyrene core/silica shell microparticles to create a site for competitive binding of the antibodies (Abs). Bound Abs are then stained with fluorophore-labeled Abs. Encoding and signaling fluorescence of the particles are determined by an automated flow cytometer.
For compatibility of the immunoassay with the 96-well microtiter plate format, a stop reagent, containing formaldehyde, is used. This enables a wash-free procedure while decreasing time-to-result. Detection limits of 140 ± 40 ng/L for CBZ, 180 ± 110 ng/L for CAF, 4 ± 3 ng/L for DCF, and 310 ± 70 ng/L for ILA are achieved, which meet the sensitivity criteria of wastewater analysis. We demonstrate the applicability of SAFIA to real wastewater samples from three different wastewater Treatment plants, finding the results in good agreement with LC-MS/MS. Moreover, the accuracy in general exceeded that from classical ELISAs. We therefore propose SAFIA as a quick and reliable approach for wastewater analysis meeting the requirements for process analytical technology.
A “turn-on” fluorescence sensing system based on a BODIPY-cobaloxime complex for the detection of H2S in liquid and gas phase was developed. To that aim, two cobaloxime complexes bearing an axial pyridyl-BODIPY ligand were initially evaluated as sensitive fluorescent HS− indicators in aqueous solution. The sensing mechanism involves the selective substitution of the BODIPY ligand by the HS− anion at the cobalt center, which is accompanied by a strong fluorescence enhancement. The selection of a complex with an ideal stability and reactivity profile toward HS− relied on the optimal interaction between the cobalt metal-center and two different pyridyl BODIPY ligands. Loading the best performing BODIPY-cobaloxime complex onto a polymeric hydrogel membrane allowed us to study the selectivity of the probe for HS− against different anions and cysteine. Successful detection of H2S by the fluorescent “light-up” membrane was not only accomplished for surface water but could also be demonstrated for relevant H2S concentrations in gas phase.
We report the first results for the immunochemical determination of the β-lactam antibiotic drug amoxicillin (AMX) in water samples by ELISA (enzyme-linked immunosorbent assay). The applied indirect competitive ELISA using a commercially available mouse anti-AMX antibody enables testing for AMX with a limit of detection of around 1 µg/L. Calibration curves of calibrators prepared in different water samples showed equal shape. This underlines the suitability of this assay for the AMX determination in these samples. Furthermore, cross-reactivities of structurally similar β-lactam antibiotics were examined and found to be low for ampicillin, penicillin G and penicillin V. In contrast, carbenicillin was recognized by the antibody even better than AMX indicating a positive effect of an additional carboxyl group on antibody binding. This is promising for further application of this assay, e.g. in the determination of the most relevant hydrolysis product of AMX, amoxicilloic acid.
Tempeh is a common food in Indonesia, produced by fungal fermentation of soybeans using Rhizopus sp., as well as Aspergillus oryzae, for inoculation. Analogously, for economic reasons, mixtures of maize and soybeans are used for the production of so-called tempeh-like products. For maize, a contamination with the mycoestrogen zearalenone (ZEN) has been frequently reported. ZEN is a mycotoxin which is known to be metabolized by Rhizopus and Aspergillus species. Consequently, this study focused on the ZEN transformation during tempeh fermentation. Five fungal strains of the genera Rhizopus and Aspergillus, isolated from fresh Indonesian tempeh and authentic Indonesian inocula, were utilized for tempeh manufacturing from a maize/soybean mixture (30:70) at laboratory-scale. Furthermore, comparable tempeh-like products obtained from Indonesian markets were analyzed. Results from the HPLC-MS/MS analyses show that ZEN is intensely transformed into its metabolites alpha-zearalenol (alpha-ZEL), ZEN-14-sulfate, alpha-ZEL-sulfate, ZEN-14-glucoside, and ZEN-16-glucoside in tempeh production. alpha-ZEL, being significantly more toxic than ZEN, was the main metabolite in most of the Rhizopus incubations, while in Aspergillus oryzae fermentations ZEN-14-sulfate was predominantly formed. Additionally, two of the 14 authentic samples were contaminated with ZEN, alpha-ZEL and ZEN-14-sulfate, and in two further samples, ZEN and alpha-ZEL, were determined. Consequently, tempeh fermentation of ZEN-contaminated maize/soybean mixture may lead to toxification of the food item by formation of the reductive ZEN metabolite, alpha-ZEL, under model as well as authentic conditions.
In the recent decade, metal pyrithione complexes have become important biocides for antifouling purposes in shipping. The analysis of metal pyrithione complexes and their degradation products/species in environmental samples is challenging because they exhibit fast UV degradation, transmetalation, and ligand substitution and are known to be prone to spontaneous species transformation within a chromatographic system. The environmental properties of the pyrithione species, e.g., toxicity to target and non-target organisms, are differing strongly, and it is therefore inevitable to identify as well as quantify all species separately. To cope with the separation of metal pyrithione species with minimum species transformation during analysis, a capillary electrophoresis (CE)–based method was developed. The hyphenation of CE with selective electrospray ionization- and inductively coupled plasma–mass spectrometry (ESI-, ICP-MS) provided complementary molecular and elemental information for the identification and quantification of pyrithione species. To study speciation of pyrithiones, a leaching experiment of several commercial antifouling paints containing zinc pyrithione in ultrapure and river water was conducted. Only the two species pyrithione (HPT) and dipyrithione ((PT)2) were found in the leaching media, in concentrations between 0.086 and 2.4 μM (HPT) and between 0.062 and 0.59 μM ((PT)2), depending on the paint and leaching medium. The limits of detection were 20 nM (HPT) and 10 nM ((PT)2). The results show that complementary CE-MS is a suitable tool for mechanistical studies concerning species transformation (e.g., degradation) and the identification of target species of metal pyrithione complexes in real surface water matrices, laying the ground for future environmental studies.
µ-FTIR spectroscopy is a widely used technique in microplastics research. It allows to simultaneously characterize the material of the small particles, fibers or fragments, and to specify their size distribution and shape. Modern detectors offer the possibility to perform two-dimensional imaging of the sample providing detailed information. However, datasets are often too large for manual evaluation calling for automated microplastic identification. Library search based on the comparison with known reference spectra has been proposed to solve this problem.
To supplement this ‘targeted analysis’, an exploratory approach was tested. Principal component analysis (PCA) was used to drastically reduce the size of the data set while maintaining the significant information. Groups of similar spectra in the prepared data set were identified with cluster analysis. Members of different clusters could be assigned to different polymer types whereas the variation observed within a cluster gives a hint on the chemical variability of microplastics of the same type. Spectra labeled according to the respective cluster can be used for supervised learning. The obtained classification was tested on an independent data set and results were compared to the spectral library search approach.
A fast and simple method for sulfur quantification in crude oils was developed by using high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS). For this, heavy crude oil samples were prepared as microemulsion (shake) and injected into a graphite furnace (shut). Finally, the concentration of sulfur was determined by monitoring in situ the transient molecular spectrum of GeS at wavelength 295.205nm after adding a germanium solution as molecular forming agent (and go). Zirconium dioxide in the form of nanoparticles (45–55nm) was employed as a permanent modifier of the graphite furnace. Calibration was done with an aqueous solution standard of ammonium sulfate, and a characteristic mass (m0) of 7.5ng was achieved. The effectiveness of the proposed method was evaluated analizing, ten heavy crude oil samples with Sulfur amounts ranging between 0.3 and 4.5% as well as two NIST standard reference materials, 1620c and 1622e. Results were compared with those obtained by routine ICP-OES analysis, and no statistical relevant differences were found.
The large number of nanomaterial-based applications emerging in the materials and life sciences and the foreseeable increasing use of these materials require methods that evaluate and characterize the toxic potential of these nanomaterials to keep safety risks to people and environment as low as possible. As nanomaterial toxicity is influenced by a variety of parameters like size, shape, chemical composition, and surface chemistry, high throughput screening (HTS) platforms are recommended for assessing cytotoxicity. Such platforms are not yet available for genotoxicity testing. Here, we present first results obtained for application-relevant nanomaterials using an automatable genotoxicity platform that relies on the quantification of the phosphorylated histone H2AX (γ-H2AX) for detecting DNA double strand breaks (DSBs) and the automated microscope system AKLIDES® for measuring integral fluorescence intensities at different excitation wavelengths. This platform is used to test the genotoxic potential of 30 nm-sized citrate-stabilized gold nanoparticles (Au-NPs) as well as micellar encapsulated iron oxide nanoparticles (FeOx-NPs) and different cadmium (Cd)-based semiconductor quantum dots (QDs), thereby also searching for positive and negative controls as reference materials. In addition, the influence of the QD shell composition on the genotoxic potential of these Cd-based QDs was studied, using CdSe cores as well as CdSe/CdS core/shell and CdSe/CdS/ZnS core/shell/shell QDs. Our results clearly revealed the genotoxicity of the Au-NPs and its absence in the FeOx-NPs. The genotoxicity of the Cd-QDs correlates with the shielding of their Cd-containing core, with the core/shell/shell architecture preventing genotoxicity risks. The fact that none of these nanomaterials showed cytotoxicity at the chosen particle concentrations in a conventional cell viability assay underlines the importance of genotoxicity studies to assess the hazardous potential of nanomaterials.
The rational synthesis and use of nanomaterials require the characterization of many different properties, ranging from particle size and size distribution over surface chemistry to more applicationrelevant features like optical, electrochemical, and magnetic properties. In the following, several methods for the characterization of functional groups on nanomaterials, like polymer and silica nanoparticles, semiconductor quantum dots, and lanthanide-based upconversion nanocrystals are presented. Additionally, procedures for the measurement of the key spectroscopic performance parameters of nanomaterials with linear and nonlinear photoluminescence, such as the photoluminescence quantum yield, are presented for the UV/vis/NIR/SWIR.
The knowledge of transformation pathways and identification of transformation products (TPs) of veterinary drugs is important for animal health, food, and environmental matters. The active agent Monensin (MON) belongs to the ionophore antibiotics and is widely used as a veterinary drug against coccidiosis in broiler farming. However, no electrochemically (EC) generated TPs of MON have been described so far. In this study, the online coupling of EC and mass spectrometry (MS) was used for the generation of oxidative TPs. EC-conditions were optimized with respect to working electrode material, solvent, modifier, and potential polarity. Subsequent LC/HRMS (liquid chromatography/high resolution mass spectrometry) and MS/MS experiments were performed to identify the structures of derived TPs by a suspected target analysis. The obtained EC-results were compared to TPs observed in metabolism tests with microsomes and hydrolysis experiments of MON.
Five previously undescribed TPs of MON were identified in our EC/MS based study and one TP, which was already known from literature and found by a microsomal assay, could be confirmed.
Two and three further TPs were found as products in microsomal tests and following hydrolysis, respectively. We found decarboxylation, O-demethylation and acid-catalyzed ring-opening reactions to be the major mechanisms of MON transformation.
The most challenging part in performing a single cell ICP-MS (sc-ICP-MS) approach is the sample preparation, in particular the reduction of the ionic background. This step is, in many cases, time-consuming and required for each sample separately. Furthermore, sc-ICP-MS measurements are mostly carried out "manually", given the fact that present systems are not allowing for an automated change of samples. Thus, within this work, we developed an approach based on a HPLC system coupled on-line with sc-ICP-MS via a set of switching valves as well as an in-line filter for automated cell washing. This set-up enables the ionic background removal as well as analysis of single cells completely automated without any manual sample pretreatment. Our approach was applied for the analysis of the single celled diatom species Cyclotella meneghiniana, a marine diatom species, on the basis of Mg24 and facilitates testing in 11 min per sample, requiring only around 10,000 cells in a volume of 10 µL and approx. 10 mL of a 5% MeOH/95% deionized water (v/v) mixture. Even at extremely saline culturing media concentrations (up to 1000 mg L-1 magnesium) our on-line approach worked sufficiently allowing for distinction of ionic and particulate fractions. Furthermore, a set of diatom samples was analyzed completely automated without the need for changing samples manually. So, utilizing this approach enables analyzing a high quantity of samples in a short time and therefore in future the investigation of ecotoxicological effects is simplified for example in terms of metal accumulation by taking biovariability into account.
The total petrol hydrocarbon (TPH) content in soil is determined by gas chromatographic separation and flame ionisation detection according to ISO 16703 in routine laboratories for about 20 years. The development of the interlaboratory variability observed with this analytical procedure over 15 years in a proficiency testing scheme conducted annually with more than 170 participants is evaluated in detail. A significant improvement of the reproducibility standard deviation among participants is observed over the years and attributed to an increasing familiarity with the procedure. Nevertheless, the determination of TPH in the environmentally relevant mass fraction range between 500 mg/kg and 10 000 mg/kg in soils or sediments is far from reaching the reproducibility standard deviations predicted by the Horwitz curve. It is seen that laboratories with sporadic participation tend to report higher bias, while a core group of laboratories participating on a regular basis arrived at reproducibility standard deviations below 20 %. Results from a given laboratory obtained on two different samples tend to be highly correlated in the same PT round indicating a sound repeatability. Expectedly, the within-laboratory correlation between results from consecutive rounds was considerably lower. However, results from consecutive rounds with a temporal distance of 1, 2 or 3 years revealed largely similar correlations which suggests that the within-laboratory reproducibility adjusts to a constant level at least after a period of 1 year.
Microplastics can affect biophysical properties of the soil. However, little is known about the cascade of events in fundamental levels of terrestrial ecosystems, i.e., starting with the changes in soil abiotic properties and propagating across the various components of soil−plant interactions, including soil microbial communities and plant traits. We investigated here the effects of six different microplastics (polyester fibers, polyamide beads, and four fragment types: polyethylene, polyester terephthalate, polypropylene, and polystyrene) on a broad suite of proxies for soil health and performance of spring onion (Allium fistulosum). Significant changes were observed in plant biomass, tissue elemental composition, root traits, and soil microbial activities. These plant and soil responses to microplastic exposure were used to propose a causal model for the mechanism of the effects. Impacts were dependent on particle type, i.e., microplastics with a shape similar to other natural soil particles elicited smaller differences from control. Changes in soil structure and water dynamics may explain the observed results in which polyester fibers and polyamide beads triggered the most pronounced impacts on plant traits and function. The findings reported here imply that the pervasive microplastic contamination in soil may have consequences for plant performance and thus for agroecosystems and terrestrial biodiversity.
Comparing Nontargeted LC-MS Methods by Co-visualizing Linear Dynamic Range and Chemical Coverage
(2019)
INTRODUCTION
Biological and environmental samples contain thousands of small molecule species that all vary in chemical properties and concentration range. Identifying and quantifying all these chemical entities remains a long-term goal in metabolomics and related systems approaches. Due to its broad selectivity, nontargeted LC-MS is usually the method of choice for broad chemical screening. Optimizing nontargeted LC-MS methods, however, is less straightforward than for targeted methods where sensitivity, specificity, linearity etc. serve as well-established performance criteria. We therefore investigated linear dynamic range (LDR) and chemical classification as alternative performance criteria to guide nontargeted method development.
EXPERIMENTAL METHODS
LDR was defined as the linear portion of a feature’s response curve over multiple concentration levels. Comparing the LDR of features across methods can be expected to be significantly more robust than comparing signal intensities for a single concentration. To determine LDR for all features, a computational workflow was implemented in the R programming language. For estimating the linear portion of a curve, several mathematical approaches including linear, non-linear and piecewise linear regression were evaluated. Chemical classification was based on ClassyFire, which computes chemical classes for a given structure. To avoid false classifications for incorrectly annotated compounds, we took the following statistical approach. For each compound, multiple likely annotation hypotheses were derived using a recently described workflow[2]. All annotation hypotheses were submitted to ClassyFire and obtained classifications were ranked by frequency. The most frequently suggested class was kept for further analysis. Finally, LDR and chemical classes were visualized together on a molecular network, which was constructed using the well-established MS/MS similarity approach.
RESULTS AND DISCUSSION
For technical validation of the workflow, several hundred curve fits obtained from the different regression models were reviewed visually. Piecewise linear regression performed the most reliably with respect to the heterogeneous curve shapes of ‘real-life’ features. Validation of chemical classification was performed against a compound library, which showed that 90% of ~450 library compounds were correctly classified using the described approach. Two liquid chromatography methods (HILIC, RPC) as well as two electrospray ionization variants (low/high-temperature ESI) applied to urinary metabolomics were exemplarily studied to test the workflow. Molecular network visualization indicated that of all analytical setups, HILIC/high temperature ESI performed best in terms of high LDR achieved over a wide range of compound classes. Despite one order of magnitude lower sensitivity, HILIC/low temperature ESI showed similar chemical coverage, except for organic nitrogen compounds that were underrepresented compared to high-temperature ESI. Both RPC setups were inferior to the HILIC setups in terms of high-LDR features, supporting previous findings for the given matrix. The higher relative representation of benzenoids and lipids in RPC demonstrated that the workflow successfully captured expected selectivity differences between chromatographies.
CONCLUSION
When comparing nontargeted LC-MS methods for optimization purposes, ideally all available quantitative and qualitative information should be integrated. The present workflow follows this idea. Visualizing LDR and chemical classes of all features on a molecular network quickly indicated differences in method selectivity that were otherwise difficult to spot. As an automated approach, it is easily applied to repeated optimization steps, enabling effective optimization strategies.
Nontargeted high-resolution mass spectrometry (HRMS) is widely used for small molecule screening in biotic or abiotic samples. However, HRMS approaches like metabolomics or environmental nontarget screening currently still lack confidence in chemical annotation, i.e. computational structure assignment to all measured mass signals. As a crucial step within the annotation pipeline, molecular weight inference (MWI) deduces a compound’s intact mass from diagnostic mass differences between MS1 peaks, allowing precise database queries in subsequent steps. As the common practice of considering all possible ionization products such as adducts, multimers, multiple charges etc. in MWI suffers from high false positive rates, we aimed at selecting candidate ionization products in a chemically sensitive way. Generally, electrospray ionization produces different types of adducts depending on chromatographic system and sample matrix, necessitating application-specific optimization for optimum MWI performance. To avoid, however, the tedious and potentially biased manual data curation connected to optimization, we established an R-based workflow for automating this task. The workflow consists of two parts. Part 1 creates an MS1 spectral library by performing peak detection, spectral deconvolution and target peak assignment based on density estimation. Part 2 analyzes ion relationships within the library and returns a list of detected ionization products ranked by their frequency. We applied the workflow to a commercial 634-compound library that was acquired for two chromatographic methods (reverse phase, RP; hydrophilic liquid interaction chromatographic, HILIC) and the two ESI modes (positive, negative). As expected, different frequency distributions of ionization products were found for the two chromatographies. Interestingly, however, some of the differences were expected in terms of solvent chemistries (e.g. [M+NH4]+ in ammonium formate-buffered HILIC) while others indicated more complex ion competition (e.g. abundant [M+K]+, [M+2K-H]+ in HILIC). This demonstrated the relevance of this empirical approach. We further show that MWI accuracy clearly benefitted from derived optimized adduct lists – by adding filters or weighting terms – and present FDR calculations supporting this observation. We conclude that chemistry-aware compound annotation based on the combination of high-throughput library acquisition and statistical analysis holds significant potential for further improvements in nontargeted small molecule HRMS.
The development of an automated miniaturized analytical system that allows for the rapid monitoring of carbamazepine (CBZ) levels in serum and wastewater is proposed. Molecular recognition of CBZ was achieved through its selective interaction with microbeads carrying anti-CBZ antibodies. The proposed method combines the advantages of the micro-bead injection spectroscopy and of the flow-based platform lab-on-valve for implementation of automatic immunosorbent renewal, rendering a new recognition surface for each sample. The sequential (or simultaneous) perfusion of CBZ and the horseradish peroxidase-labelled CBZ through the microbeads is followed by real-time on-column Monitoring of substrate (3,30,5,50-tetramethylbenzidine) oxidation by colorimetry. The evaluation of the initial oxidation rate and also the absorbance value at a fixed time point provided a linear response versus the logarithm of the CBZ concentration. Under the selected assay conditions, a single analysis was completed after only 11 min, with a quantification range between 1.0 and 50 µg L⁻¹. Detection of CBZ levels in undiluted wastewater samples was feasible after a simple filtration step while good recoveries were attained for spiked certified human serum, analyzed without sample clean-up.
The efficiency, relatively low cost and eco-friendly nature of hydrogen peroxide-assisted photocatalysis treatment procedures are significant advantages over conventional techniques for wastewater remediation. Herein, we evaluate the behaviour of g-cyclodextrin (g-CD) immobilised on either bare or chitosan (CS)–functionalised Fe3O4 nanoparticles, for photodegrading Bisphenol A (BPA) in ultrapure water and in real wastewater samples. The BPA removal efficiencies with Fe3O4/g-CD and Fe3O4/CS/g-CD were compared with those of Fe3O4/b-CD, and were monitored under UVA irradiation at near-neutral pH. The addition of H2O2 at low concentrations (15 mmol L-1) significantly increased BPA photodegradation in the presence of each nanocomposite. The highest catalytic activity was shown by both Fe3O4/g-CD and Fe3O4/CS/g-CD nanocomposites (,60 and 27%BPA removal in ultrapure water and real wastewater effluent, respectively). Our findings reveal the superior performance of g-CD-functionalised Fe3O4 relative to that of Fe3O4/b-CD. The use of CD-based nanocomposites as photocatalytic materials could be an attractive option in the pre- or post-treatment stage of wastewaters by advanced oxidation processes before or after biological treatment.
Gallium – a versatile element for tuning the photoluminescence properties of InP quantum dots
(2019)
With the goal to tune the emission properties of colloidal InP quantum dots, the incorporation of Ga was explored. Unexpectedly, depending on the nature of the gallium precursor, the photoluminescence shifted either to the red (gallium oleate) or to the blue (gallium acetylacetonate). In the first case, larger-sized InP/GaP core/shell nanocrystals were formed, while in the second case the formation of an InGaP alloy structure enabled the blue range of emission (475 nm) to be accessed.
Aldehyde moieties on 2D-supports or microand nanoparticles can function as anchor groups for the attachment of biomolecules or as reversible binding sites for proteins on cell surfaces. The use of aldehyde-based materials in bioanalytical and medical settings calls for reliable methods to detect and quantify this functionality. We report here on a versatile concept to quantify the accessible aldehyde moieties on particle surfaces through the specific binding and subsequent release of small reporter molecules such as fluorescent dyes and nonfluorescent chromophores utilizing acylhydrazone formation as a reversible covalent labeling strategy. This is representatively demonstrated for a set of polymer microparticles with different aldehyde labeling densities. Excess reporter molecules can be easily removed by washing, eliminating inaccuracies caused by unspecific adsorption to hydrophobic surfaces. Cleavage of hydrazones at acidic pH assisted by a carbonyl trap releases the fluorescent reporters rapidly and quasi-quantitatively and allows for their fluorometric detection at low concentration. Importantly, this strategy separates the signal-generating molecules from the bead surface. This circumvents common issues associated with light scattering and signal distortions that are caused by binding-induced changes in reporter fluorescence as well as quenching dye−
dye interactions on crowded particle surfaces. In addition, we demonstrate that the release of a nonfluorescent chromophore via disulfide cleavage and subsequent quantification by absorption spectroscopy gives comparable results, verifying that both assays
are capable of rapid and sensitive quantification of aldehydes on microbead surfaces. These strategies enable a quantitative
comparison of bead batches with different functionalization densities, and a qualitative prediction of their coupling efficiencies in bioconjugations, as demonstrated in reductive amination reactions with Streptavidin.
As part of the BonaRes research initiative, funded by the BMBF, strategies are being developed to use soil as a sustainable resource in the bio economy. The interdisciplinary subproject I4S - “Intelligence for soil” - is responsible for the development of an integrated system for site-specific management of soil fertility. For this purpose, a platform is constructed and various sensors are installed. Real-time data will be summarised in models and decision-making algorithms will be used to control fertilisation and accordingly improve soil functions. Aim of the BAM in the frame of I4S is the characterisation of an energy-dispersive X-ray fluorescence (EDXRF) based sensor for robust determination of plant essential nutrients in soil.
First a principal component analysis (PCA) was used to identify outliers and to observe the largest variance within the German soil samples. It could be monitored that splitting of the samples was due to their iron content. Given that clay samples contain high amounts of iron and sandy samples low amounts, a classification of the samples by their soil texture according to VD LUFA was possible. Considering the complex composition of soil, a matrix-specific calibration was carried out by univariate and multivariate data analysis. The figures of merit demonstrated that a more robust calibration model with negligible matrix effects can be obtained by a multivariate approach using partial least squares regression (PLSR). A better correlation between predicted values compared to reference values for German soil samples was observed for the chemometric calibration model than for the univariate one.
Different factors can affect the received calibration models such as moisture and particle size distribution which is especially important due to later online analysis.
In first studies the influence of moisture on the detection of plant essential nutrients was investigated. With increasing water content, the characteristic fluorescence peaks decrease and start to increase again at a water content of 15 %. With lower moisture content the soil agglomerates which leads to lower packing of the sample, resulting in a rougher surface which negatively influence the signals. Whereas, agglomerates are not formed at higher water content. This allows the sample to be packed more tightly thus a smoother surface and a better homogeneity is obtained.
Furthermore, particle size distribution leads to significantly higher uncertainties and lower signals when comparing grounded (< 500 μm) and not grounded (< 2 mm) samples. This can be explained by amplifying of the already known inhomogeneity of soils.
Both factors must be included in the chemometric PLSR to obtain robust calibration models for each macro and micro nutrient.
Im Rahmen der vom BMBF geförderten Forschungsinitiative BonaRes werden Strategien entwickelt, um Boden als nachhaltige Ressource in der Bioökonomie zu nutzen. Das interdisziplinäre Teilprojekt I4S - „Intelligenz für den Boden“ - ist verantwortlich für die Entwicklung eines integrierten Systems zur standortspezifischen Steuerung der Bodenfruchtbarkeit. Zu diesem Zweck wird eine Plattform gebaut, auf der verschiedene Sensoren installiert sind. Echtzeitdaten werden in Modellen zusammengefasst und Entscheidungsalgorithmen werden verwendet, um die Düngung zu steuern und die Bodenfunktionen entsprechend zu verbessern. Ziel der BAM im Rahmen von I4S ist die Charakterisierung eines energiedispersiven Röntgenfluoreszenzsensors (EDXRF) zur robusten online-Bestimmung von Makro- und Mikronährstoffen im Boden. Zunächst wurde eine Hauptkomponentenanalyse (PCA) durchgeführt, um Ausreißer zu identifizieren und die größte Varianz innerhalb der deutschen Bodenproben zu beobachten. Es konnte festgestellt werden, dass die Aufspaltung der Proben auf ihren Eisengehalt zurückzuführen ist. Da Tonproben hohe Mengen an Eisen und Sandproben geringe Mengen enthalten, war eine Klassifizierung der Proben nach ihrer Bodentextur nach VD LUFA möglich. In Anbetracht der komplexen Bodenzusammensetzung wurde eine matrixspezifische Kalibrierung durch univariate und multivariate Datenanalyse durchgeführt. Die analytischen Güteziffern zeigen, dass ein robusteres Kalibriermodell mit vernachlässigbaren Matrixeffekten durch einen multivariaten Ansatz unter Verwendung der partiellen Regression kleinster Quadrate (PLSR) erhalten werden kann. Verschiedene Faktoren können die erhaltenen Kalibriermodelle beeinflussen, wie z. B. Feuchtigkeit und Partikelgrößenverteilung, was aufgrund der späteren online-Analyse besonders wichtig ist. In ersten Studien wurde der Einfluss von Feuchtigkeit auf den Nährstoffnachweis untersucht. Mit zunehmendem Wassergehalt nehmen die charakteristischen Fluoreszenzpeaks ab und beginnen bei einem Wassergehalt von 15% wieder anzusteigen. Bei geringerem Feuchtigkeitsgehalt agglomeriert der Boden, was zu einer geringeren Packung der Probe führt, dementsprechend zu einer raueren Oberfläche, die die Signale negativ beeinflusst. Bei höherem Wassergehalt bilden sich keine Agglomerate. Dadurch kann die Probe enger gepackt werden, wodurch eine glattere Oberfläche und eine bessere Homogenität erhalten wird. Darüber hinaus führt die Partikelgrößenverteilung beim Vergleich von gemahlenen und nicht gemahlenen Proben zu signifikant höheren Unsicherheiten und niedrigeren Signalen. Beide Faktoren müssen in die chemometrische PLSR einbezogen werden, um zuverlässige Kalibrierungsmodelle für jeden Nährstoff zu erhalten.
Draft standards for the determination of organic pollutants in the solid matter of environmental matrices such as sludge, treated biowaste and soil have been basically developed in the framework of the European standardization project HORIZONTAL. A research project financed by the German Federal Environment Agency was initiated to finalize some of these CEN standard drafts, since fully validated standard procedures are crucial for the evaluation of their reliability in the context of implementation in legislation on environmental health.
Approach: Appropriate test materials (< 2mm particle size) were prepared and homogenized from contaminated soils, sludge and treated biowaste containing polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), dioxins, furans and dioxin-like-PCB and served, along with reference solutions, as the basis for international interlaboratory comparisons. Performance data of three analytical standard procedures were obtained by the statistical evaluation of results received from 11 to 29 participants per test material.
Results: The overall variation coefficients of reproducibility (between-lab standard deviations) for the sum parameters were roughly between 10 and 35 %. The variation coefficients of repeatability (within-lab standard deviations) range between 3 % and 8 % and show no trend considering the substance groups or matrices.
The highest coefficients of reproducibility were found for the analysis of PAHs, which were between 26 and 35 %, depending on the matrix, whereas 7-17 % reproducibility was observed for toxicity equivalents (TEQ) comprising dioxins, furans and dl-PCB.
Conclusions: Overall, the results confirm that the procedures described in the Technical Specifications are fit for purpose for all three matrices and that the feasibility of the HORIZONTAL approach, to cover several matrices with one standard per analyte, was thereby proven.
Gasoline adulteration is a frequent problem world-wide, because of the chance of quick, maximized profits. However, addition of cheaper ethanol or hydrocarbons like kerosene does not only result in economic damage but also poses problems for vehicles and the environment. To enable law enforcement forces, customers or enterprises to uncover such a fraudulent activity directly upon suspicion and without the need to organize for sampling and laboratory analysis, we developed a simple strip-based chemical test. Key to the favorable performance was the dedicated materials tailoring, which led to test strips that consisted of a cellulose support coated with silica, passivated with hexamethyldisilazane and functionalized covalently with a molecular probe. The probe fluoresces brightly across a broad solvent polarity range, enabling reliable quantitative measurements and data analysis with a conventional smartphone. The assays showed high reproducibility and accuracy, allowing not only for the detection of gasoline adulteration but also for the on-site monitoring of the quality of commercial E10 gasoline.
Mykotoxine in Lebensmitteln stellen weltweit Probleme dar, Zearalenon in Speiseöl ist ein solches. Neue Hydrazinbasierte Analyseverfahren können jetzt helfen, den EU-Grenzwert besser zu kontrollieren. Aber auch die Strukturaufklärung von Transformationsprodukten und verlässliche Kalibrierstandards sind aktuelle Herausforderungen.
1,3,5-Tris-(2,3-dibromopropyl)-1,3,5-triazine-2,4,6-trione (TDBP-TAZTO) is an emerging brominated flame retardant which is widely used in several plastic materials (electric and electronic equipment, musical instruments, automotive components).
However, until today, no photochemical studies as well as the identification of possible phototransformation products (PTPs) were described in literature. Therefore, in this study, UV-(C) and simulated sunlight irradiation experiments were performed to investigate the photolytic degradation of TDBP-TAZTO and to identify relevant PTPs for the first time. The UV-(C) Irradiation experiments show that the photolysis reaction follows a first-order kinetic model. Based on this, the photolysis rate constant k as well as the half-life time t1/2 were calculated to be k = (41 ± 5 ×10−3) min−1 and t1/2=(17±2) min. In comparison, a minor degradation of TDBP-TAZTO and no formed phototransformation products were obtained under simulated sunlight. In order to clarify the photochemical behavior, different chemicals were added to investigate the influence on indirect photolysis: (i) H2O2 for generation of hydroxyl radicals and (ii) two quenchers (2-propanol, sodium azide) for scavenging oxygen species which were formed during the irradiation experiments. Herein, nine previously unknown PTPs of TDBP-TAZTO were detected under UV-(C) irradiation and identified by HPLC-(HR)MS. As a result, debromination, hydroxylation, and dehydrobromination reactions could be presumed as the main degradation pathways by high-resolution mass spectrometry. The direct as well as the OH radical-induced indirect photolysis were observed.
Since cereals constitute a staple food worldwide, monitoring of growth, storage and processing represent a perseverative challenge of analytical sciences. Especially during storage infested grains breed fungal clusters (“hot spots”) in which mycotoxins accumulate and can highly exceed allowed maximum levels. Because of their unpredictable presence, analytical procedures – including representative sampling - contain invasive and time intensive steps.
To avoid erroneously negative results in mycotoxin analysis in cereals, the samples´ homogeneous headspace might be investigated instead of analyzing subsamples of the grains. So-called microbial volatile organic compounds (MVOC´s) provide information for instance about the fungal status of grains. Previous investigations revealed trichodiene to be a precursor of trichothecene mycotoxins which comprises more than 180 different compounds. Due to its non-functionalised sesquiterpene structure, quantification of trichodiene using Headspace GC-MS methods is possible. Thereby, it could be used as biomarker for trichothecene contamination of cereals.
Nevertheless, further investigations are necessary. To be able to draw conclusion about the trichothecene content in cereal samples, a possible correlation between trichodiene concentration in the gas phase and trichothecene concentration in the sample must be examined. Realizing this idea would widely extend the applicability of trichodiene and enormously simplify trichothecene detection. Hence, the first step of an ongoing study aims to develop a laboratory reference method using trichodiene as volatile biomarker to quantify trichothecenes in cereals. Both static headspace and SPME-enrichment coupled to gas chromatography with mass spectrometry (GC-MS) were tested and compared. In a second step, this reference method is intended to validate new approaches for fast on-site screening of trichodiene in cereals.
Two nanosensors for simultaneous optical measurements of temperature (“T”), oxygen (“O”), and pH (“P”) have been designed. These “TOP” nanosensors are based on 100 nm-sized silica-coated polystyrene nanoparticles (PS-NPs) doped with the near infrared emissive oxygen- and temperature-sensitive chromium(III) complex ([Cr(ddpd)2][BPh4]3 CrBPh4)[1][2] and an inert reference fluorescence dye (Nile Red NR or 5,10,15,20-tetrakis-(pentafluorophenyl) porphyrin TFPP) and are covalently labeled with the pH-sensitive fluorophore fluorescein isothiocyanate (FITC). These emitters can be excited at the same wavelength and reveal distinguishable emission spectra suitable for ratiometric intensity-based and time-resolved studies in the visible and near infrared spectral region. The core-shell nanostructure of these sensors reveals high colloidal stability in various aqueous media. Studies in PBS buffer solutions and in a model body liquid demonstrate the applicability of the TOP nanosensors for optically detecting the three bioanalytically and biologically relevant analytes temperature, oxygen and pH simultaneously at the same position.
Two nanosensors for simultaneous optical measurements of temperature (“T”), oxygen (“O”), and pH (“P”) have been designed. These “TOP” nanosensors are based on 100 nm-sized silica-coated polystyrene nanoparticles (PS-NPs) doped with the near infrared emissive oxygen- and temperature-sensitive chromium(III) complex ([Cr(ddpd)2][BPh4]3 CrBPh4)[1][2] and an inert reference fluorescence dye (Nile Red NR or 5,10,15,20tetrakis-(pentafluorophenyl) porphyrin TFPP) and are covalently labeled with the pHsensitive fluorophore fluorescein isothiocyanate (FITC). These emitters can be excited at the same wavelength and reveal distinguishable emission spectra suitable for ratiometric intensity-based and time-resolved studies in the visible and near infrared spectral region. The core-shell nanostructure of these sensors reveals high colloidal stability in various aqueous media. Studies in PBS buffer solutions and in a model body liquid demonstrate the applicability of the TOP nanosensors for optically detecting the three bioanalytically and biologically relevant analytes temperature, oxygen and pH simultaneously at the same position.
The knowledge of transformation pathways and identification of transformation products (TPs) of veterinary drugs is important for health, food and environmental matters. Monensin (MON) is an ionophore antibiotic widely used to cure and prevent coccidiosis by chicken especially in broiler farming. Residues are not only found in food products (chicken and eggs) but also in the environment (manure, soil or water). Several transformation processes can alter the parent compound MON, ranging from biotransformation in living organism to biotic/abiotic and microbial processes in environmental matters.
The main objective of this work was to investigate the potential of electrochemistry (EC) to simulate oxidative transformation processes and to predict TPs of MON. An electrochemical reactor was used consisting of a flow-through cell with a glassy carbon working electrode. Derived TPs were analyzed by online coupling of EC and high-resolution mass spectrometry (HRMS) and LC-HRMS offline measurements. Among the generated TPs already known as well as unknown TPs of MON could be found.
Additionally, MON was subjected also to other transformation methods such as Fenton reaction, photochemical and hydrolysis experiments as well as metabolism tests with microsomes. As a result, different targeted and suspected TPs could be identified by analysis with LC-HRMS.
An overview of detected/identified TPs from this study will be presented in comparison to literature known metabolites and TPs.
Working towards a comprehensive understanding of introduction pathways, number, and fate of micro¬plastics in the environment, suitable analytical methods are a precondition. Micro-spectroscopic methods are probably the most widely used techniques. Besides their ability to measure single spectra of a particle or fiber, most modern FTIR- and Raman microscopes are also capable of two-dimensional imaging. This is very appealing to microplastics research because it allows to simultaneously characterize the analytes chemically as well as their size (distribution) and shape.
Two-dimensional imaging on extensive sample areas with FTIR-micros¬copes is facilitated by focal plane array (FPA) detectors resulting in large data sets comprised of up to several million spectra. With numbers too large for manual inspection of each individual spectrum, automated data evaluation is inevitable. Identifying different polymers based on the comparison with known reference spectra (library search) has proven to be a suitable approach. For that purpose, FTIR-spectra of common plastics can be collected to create an individual reference library.
To Supplement this ‘targeted analysis’, looking for known substances via library search, an exploratory approach was tested. Principal component analysis (PCA) proved to be a helpful tool to drastically reduce the size of the data set while maintaining the significant information. Subsequently, cluster analysis was used to find groups of similar spectra. Spectra found in different clusters could be assigned to different polymer types. The variation observed within clusters gives a hint on chemical variability of microplastics of the same polymer found in the sample. Spectra labeled according to the respective cluster/polymer type were used to build a classification model which allowed to quickly predict the polymer type based on the FTIR spectrum. Classification was tested on a second, independent data set and results were compared to the spectral library search procedure.
Over the last few years, there has been a growing interest to apply spectroscopic methods to the agricultural field for better understanding of soil properties and for efficient, sustainable management of arable land. Within the project I4S (intelligence for soil), funded by the BMBF, an integrated system for site-specific soil fertility management is developed, consisting of different sensors like X-Ray fluorescence analysis (XRF), near-infrared spectroscopy (NIR) and laser-induced breakdown spectroscopy (LIBS). LIBS provides a fast and simultaneous multi-element analysis with little to no sample preparation, which makes it a suitable method for real-time analysis on the field.
The quantification of macro and micro nutrients in soils with LIBS is challenging due to matrix effects, different levels of moisture content and varying grain sizes. First studies revealed that the problems with matrix effects can be overcome by using well characterised soils as reference materials and chemometric tools like Partial Least Squares Regression (PLSR) for calibration.
The next step was to investigate the influence of moisture and grain sizes on the LIBS signal, which is a big issue when measuring directly on the field. The results showed that the LIBS signal decreases exponentially with increasing moisture content, as most of the laser energy is used for vaporising the water. With moisture contents of 30 % or higher almost no signal can be detected. This decrease is more severe for sandy soils than for clay soils. First tests of different grain size distributions indicate that the variation of the LIBS signal increases with growing amounts of larger grains. This results in a higher standard deviation, because of a poorer reproducibility of the plasma formation and plasma characteristic. With the help of chemometric tools the influence of moisture and grain sizes should be implemented in the calibration model for accurate analysis of nutrient composition in agricultural soils.
Over the last few years, there has been a growing interest to apply spectroscopic methods to the agricultural field for better understanding of soil properties and for efficient, sustainable management of arable land. Within the project I4S (intelligence for soil), funded by the BMBF, an integrated system for site-specific soil fertility management is developed, consisting of different sensors like X-Ray fluorescence analysis (XRF), near-infrared spectroscopy (NIR) and laser-induced breakdown spectroscopy (LIBS). LIBS provides a fast and simultaneous multi-element analysis with little to no sample preparation, which makes it a suitable method for real-time analysis on the field.
The quantification of macro and micro nutrients in soils with LIBS is challenging due to matrix effects, different levels of moisture content and varying grain sizes. First studies revealed that the problems with matrix effects can be overcome by using well characterised soils as reference materials and chemometric tools like Partial Least Squares Regression (PLSR) for calibration.
The next step was to investigate the influence of moisture and grain sizes on the LIBS signal, which is a big issue when measuring directly on the field. The results showed that the LIBS signal decreases exponentially with increasing moisture content, as most of the laser energy is used for vaporising the water. With moisture contents of 30 % or higher almost no signal can be detected. This decrease is more severe for sandy soils than for clay soils. First tests of different grain size distributions indicate that the variation of the LIBS signal increases with growing amounts of larger grains. This results in a higher standard deviation, because of a poorer reproducibility of the plasma formation and plasma characteristic. With the help of chemometric tools the influence of moisture and grain sizes should be implemented in the calibration model for accurate analysis of nutrient composition in agricultural soils.
Over the last few years, there has been a growing interest to apply spectroscopic methods to the agricultural field for better understanding of soil properties and for efficient, sustainable management of arable land. Within the project I4S (intelligence for soil), funded by the BMBF, an integrated system for site-specific soil fertility management is developed, consisting of different sensors like X-Ray fluorescence analysis (XRF), near-infrared spectroscopy (NIR) and laser-induced breakdown spectroscopy (LIBS). LIBS provides a fast and simultaneous multi-element analysis with little to no sample preparation, which makes it a suitable method for real-time analysis on the field.
The quantification of macro and micro nutrients in soils with LIBS is challenging due to matrix effects, different levels of moisture content and varying grain sizes. First studies revealed that the problems with matrix effects can be overcome by using well characterised soils as reference materials and chemometric tools like Partial Least Squares Regression (PLSR) for calibration.
The next step was to investigate the influence of moisture and grain sizes on the LIBS signal, which is a big issue when measuring directly on the field. The results showed that the LIBS signal decreases exponentially with increasing moisture content, as most of the laser energy is used for vaporising the water. With moisture contents of 30 % or higher almost no signal can be detected. This decrease is more severe for sandy soils than for clay soils. First tests of different grain size distributions indicate that the variation of the LIBS signal increases with growing amounts of larger grains. This results in a higher standard deviation, because of a poorer reproducibility of the plasma formation and plasma characteristic. With the help of chemometric tools the influence of moisture and grain sizes should be implemented in the calibration model for accurate analysis of nutrient composition in agricultural soils.
Evidence for the formation of difluoroacetic acid in chlorofluorocarbon-contaminated ground water
(2019)
The concentrations of difluoroacetic acid (DFA) and trifluoroacetic acid (TFA) in rainwater and surface water from Berlin, Germany resembled those reported for similar urban areas, and the TFA/DFA ratio in rainwater of 10:1 was in accordance with the literature. In contrast, nearby ground water historically contaminated with 1,1,2-trichloro-1,2,2-trifluoroethane (R113) displayed a TFA/DFA ratio of 1:3. This observation is discussed versus the inventory of microbial Degradation products present in this ground water along with the parent R113 itself. A microbial Transformation of chlorotrifluoroethylene (R1113) to DFA so far has not been reported for environmental media, and is suggested based on well-established mammalian metabolic pathways.
Bisphenol A (BPA) is a chemical that has been used in the production of plastics for more than 40 years. BPA released from bottles made of polycarbonates has been identified as a potential endocrine disrupting substance. Comprehensive research has been undertaken to test and verify its effect on animals and human beings.
Many methods have been proposed for the determination of BPA, in particular, gas and liquid chromatography. The main disadvantages of such approaches are the high cost of the equipment, the significant duration of an analysis, and difficulties in screening a large number of samples. Lateral Flow ImmunoAssay (LFIA) attributes are high throughput, high specificity and sensitivity, as well as low cost and simplicity.
An LFIA test strip was developed. This LFIA is based on anti-BPA antibodies (from mouse) conjugated with gold nanoparticles as the marker by passive absorption and covalent coupling, deposited in an elaborate pad. To form control and test zones, anti-mouse antibody and a BVA-BSA conjugate were spotted on the nitrocellulose membrane, respectively.
Negative samples are revealed by red lines both in the test and control zones, respectively, whereas positive samples produce a single red line only in the control zone. The measurement range is 0.05 – 23 μg/L, visually detected by the naked eye within 5 minutes. In addition, the intensities at the test line can be read by dedicated lateral flow readers (opTrilyzer® and Cube by opTricon, Berlin) for a more precise and documented determination.
Two nanosensors for simultaneous optical measurements of the bioanalytically and biologically relevant analytes temperature (“T”), oxygen (“O”), and pH (“P”) have been designed. These “TOP” nanosensors are based on 100 nmsized silica-coated polystyrene nanoparticles (PS-NPs) doped with a near-infrared emissive oxygen- and temperature-sensitive chromium(III) complex ([Cr(ddpd)2][BPh4]3, CrBPh4) and an inert reference dye (Nile Red, NR or 5,10,15,20tetrakis(pentafluorophenyl) porphyrin, TFPP) and are covalently labeled with pHsensitive fluorescein isothiocyanate (FITC). These emitters can be excited at the same wavelength and reveal spectrally distinguishable emission bands, allowing for ratiometric intensity-based and time-resolved studies in the visible and near-infrared wavelength region. Studies in PBS buffer solutions and in a model body liquid demonstrate the applicability of these nanosensors for the sensitive luminescence readout of TOP simultaneously at the same spatialposition.
The formation of transformation products (TPs) from contaminants and residues is becoming an increasing focus of scientific community. All organic compounds can form different TPs, thus demonstrating the complexity and interdisciplinarity of this topic. The properties of TPs could stand in relation to the unchanged substance or be more harmful and persistent. To get important information about the generated TPs, methods are needed to simulate natural and manmade transformation processes. Current tools are based on metabolism studies, photochemical methods, electrochemical methods, and Fenton's reagent. Finally, most transformation processes are based on redox reactions. This review aims to compare these methods for structurally different compounds. The groups of pesticides, pharmaceuticals, brominated flame retardants, and mycotoxins were selected as important residues/contaminants relating to their worldwide occurrence and impact to health, food, and environmental safety issues. Thus, there is an increasing need for investigation of transformation processes and identification of TPs by fast and reliable methods.
Carbon dots have attracted much attention due to their unique optical, chemical and electronic properties enabling a wide range of applications. The properties of carbon dots can be effectively adjusted through modifying their chemical composition. However, a major challenge remains in understanding the core and surface contributions to optical and electronic transitions. Here, three blue luminescent carbon dots with carboxyl, amino and hydroxyl groups were comprehensively characterized by UV-vis absorption and emission spectroscopy, synchrotron-based X-ray spectroscopy, and infrared spectroscopy. The influence of the surface functionality on their fluorescence was probed by pH-dependent photoluminescence measurements. Moreover, the hydrogen bonding interactions between water and the surface groups of carbon dots were characterized by infrared spectroscopy. Our results show that both core and surface electronic states of blue luminescent carbon dots contribute to electronic acceptor levels while the chemical nature of the surface groups determines the hydrogen bonding behavior of the carbon dots. This comprehensive spectroscopic study demonstrates that the surface chemistry has a profound influence on the electronic configuration and surface–water interaction of carbon dots, thus affecting their photoluminescence properties.
Photon upconversion nanomaterials have a wide range of applications, including biosensing and deep-tissue imaging. Their typically very weak and narrow absorption bands together with their size dependent luminescence efficiency can limit their application potential. This has been addressed by increasingly sophisticated core-shell particle architectures including the sensitization with organic dyes that strongly absorb in the near infrared (NIR). In this work, we present a simple water-dispersible micellar system that features energy transfer from the novel NIR excitable dye, 1859 SL with a high molar absorption coefficient and a moderate fluorescence quantum yield to oleate-capped NaYF4:20%Yb(III), 2%Er(III) upconversion nanoparticles (UCNP) upon 808 nm excitation. The micelles were formed using the surfactants Pluronic F-127 and Tween 80 to produce a hydrophilic dye-UCNP system. Successful energy transfer from the dye to the UCNP could be confirmed by emission measurements that revealed the occurrence of upconversion emission upon excitation at 808 nm and an enhancement of the green Er(III) emission compared to direct Er(III) excitation at 808 nm.
Aim: To observe the variation in accumulation of Fusarium and Alternaria mycotoxins across a topographically heterogeneous field and tested biotic (fungal and bacterial abundance) and abiotic (microclimate) parameters as explanatory variables.
Methods and Results: We selected a wheat field characterized by a diversified topography, to be responsible for variations in productivity and in canopy-driven microclimate. Fusarium and Alternaria mycotoxins where quantified in wheat ears at three sampling dates between flowering and harvest at 40 points.
Tenuazonic acid (TeA), alternariol (AOH), alternariol monomethyl ether (AME), tentoxin (TEN), deoxynivalenol (DON), zearalenone (ZEN) and deoxynivalenol-3-Glucoside (DON.3G) were quantified. In canopy temperature, air and soil humidity were recorded for each point with data-loggers. Fusarium spp. as trichothecene producers, Alternaria spp. and fungal abundances were assessed using qPCR. Pseudomonas fluorescens bacteria were quantified with a culture based method. We only found DON, DON.3G, TeA and TEN to be ubiquitous across the whole field, while AME, AOH and ZEN were only occasionally detected. Fusarium was more abundant in spots with high soil humidity, while Alternaria in warmer and drier spots. Mycotoxins correlated differently to the observed explanatory variables: positive correlations between DON accumulation, tri 5 gene and Fusarium abundance were clearly detected.
The correlations among the others observed variables, such as microclimatic conditions, varied among the sampling dates. The results of statistical model identification do not exclude that species coexistence could influence mycotoxin production.
Conclusions: Fusarium and Alternaria mycotoxins accumulation varies heavily across the field and the sampling dates, providing the realism of landscapescale studies. Mycotoxin concentrations appear to be partially explained by biotic and abiotic variables.
Significance and Impact of the Study: We provide a useful experimental design and useful data for understanding the dynamics of mycotoxin biosynthesis in wheat.