Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (18)
- Vortrag (3)
- Beitrag zu einem Tagungsband (2)
- Posterpräsentation (1)
Schlagworte
- Fluorescence (13)
- Microfluidics (6)
- Smartphone (6)
- Fluoreszenz (4)
- Mikrofluidik (3)
- Rapid test (3)
- Test strip (3)
- Adulteration (2)
- Air quality (2)
- Chlorine (2)
Organisationseinheit der BAM
- 1 Analytische Chemie; Referenzmaterialien (21)
- 1.9 Chemische und optische Sensorik (21)
- 8 Zerstörungsfreie Prüfung (4)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (4)
- 1.8 Umweltanalytik (2)
- 4 Material und Umwelt (1)
- 4.0 Abteilungsleitung und andere (1)
- MP Mitglied des Präsidiums (1)
- PST Präsidiale Stabsstelle (1)
Paper des Monats
- ja (2)
Eingeladener Vortrag
- nein (3)
In the present paper the development of a semi-automated device for long-term monitoring of gaseous ammonia is described. A sensor material was produced that changes its optical properties in the pres-ence of low concentrations of ammonia in air. The implementation into an electronic device enables precise, simple, economic and fast monitoring of low concentrations of harmful gases, like ammonia, and hence can help to improve the climate monitoring in livestock housing, barns or stables.
2,4-D ist ein in der Landwirtschaft weitverbreitetes Pflanzenschutzmittel, das Grundwasser kontaminiert, sich innerhalb der Nahrungskette anreichert und Umwelt- und Gesundheitsprobleme verursachen kann. Hier stellen die Autoren ein mikrofluidisches Nachweissystem für die Echtzeitdetektion von 2,4-D in Grund- oder Oberflächenwasser vor. Es basiert auf der Kombination 2,4-D-selektiver, fluoreszierender, molekular geprägter Polymer-(MIP-)Mikropartikel mit einem 3D-mikrofluidischen Extraktions- und Detektionssystem. Messungen vor Ort sollen damit künftig möglich sein.
Chlorination of pool water and wastewater, in food and pharmaceutical production, as well as in pesticide and paper manufacturing is a routinely used technique. However, the amount of chlorine in water must be strictly adjusted, to ensure enough concentration to kill pathogenic bacteria and viruses, while preventing too high concentrations inducing negative effects on human health. As an indicator, a molecular fluorescent probe based on a BODIPY structure was designed. This indicator exhibits a sensitive and selective fluorescence response upon increasing concentrations of hypochlorite in aqueous solvent mixtures. Real-time analyses became possible after the integration of this fluorescent indicator into newly designed 2D & 3D microfluidic chips incorporating a passive sinusoidal mixer and a micro-hydrocyclone, respectively. A comparison of the two microfluidic systems, including their ability to prevent accumulation or circulation of microbubbles, has shown excellent fluidic behaviour for the micro-hydrocyclone device. This system was distinctly more robust against gas bubbles, showed a higher signal gain and allowed to halve the limit of detection to 0.02 mg L–1. The use of the 3D system to quantify the chlorine content of pool water samples for sensitive and quantitative chlorine monitoring has been demonstrated.
The present paper describes the development of a sensor material that changes its fluorescence in the presence of gaseous ammonia in a relevant concentration range. The implementation into a semi-automatic gas measurement device enables low-cost, precise, simple and fast monitoring of low con-centrations of harmful gases, like ammonia, and hence can help to improve the climate monitoring in livestock housing, barns or stables.
The globe's seas were used as dumping ground after the world wars and those millions of ammunition, most of all containing 2,4,6-trinitrotoluene (TNT), represent a pressing danger for fishermen, dredging operations, submarine cable installations and tourism. We developed an extremely selective indication method for TNT based on a specific reaction that produces a highly fluorescent compound. The indication system was integrated into a microfluidic PDMS chip for the solid-liquid extraction of TNT from water samples, offering environmental monitoring possibilities. Combining the advantages of a light-up indicator, microfluidics and a smartphone as detector, the embedded sensor allows for the remote and rapid detection of TNT down to ng in surface and sea waters.
A droplet-based microfluidic sensor was developed for the detection of Hg2+ traces in water. The approach uses gated mesoporous nanoparticles loaded with a fluorescent BODIPY dye. The squaraine-based gating mechanism is highly selective for Hg2+ and the indicator release mechanism ensures sensitive detection. The microfluidic system is modular and was assembled from simple PTFE/PFA tubes, while detection was realized with standard optomechanic, optic, and electronic parts. The sensor shows a stable response without memory effects and allows the detection of Hg2+ in water down to 20 ppt.
A novel synthetic strategy toward highly fluorinated BODIPY dyes with exceptional photostabilities relying on sustainable gold catalysis has been developed. A key to the tailored pyrrole precursors is the gold catalysis performed in ionic liquids as the reaction medium, allowing a facile recycling of the catalysts. The dyes prepared are well-matching with the spectral windows of popular rhodamine dyes and possess high brightness while showing a distinctly higher photostability than the rhodamines especially in aprotic solvents.
Microfluidic electrochemical immunosensor for the trace analysis of cocaine in water and body fluids
(2018)
Quick but accurate testing and on‐the‐spot monitoring of cocaine in oral fluids and urine continues to be an important toxicological issue. In terms of drug testing, a number of devices have been introduced into the market in recent decades, notably for workplace inspection or roadside testing. However, these systems do not always fulfill the requirements in terms of reliability, especially when low cut‐off levels are required. With respect to surface water, the presence of anthropogenic small organic molecules such as prescription and over‐the‐counter pharmaceuticals as well as illicit drugs like cannabinoids, heroin, or cocaine, has become a challenge for scientists to develop new analytical tools for screening and on‐site analysis because many of them serve as markers for anthropogenic input and consumer behavior. Here, a modular approach for the detection of cocaine is presented, integrating an electrochemical enzyme‐linked immunosorbent assay (ELISA) performed on antibody‐grafted magnetic beads in a hybrid microfluidic sensor utilizing flexible tubing, static chip and screen‐printed electrode (SPE) elements for incubation, recognition, and cyclic voltammetry measurements. A linear response of the sensor vs. the logarithm of cocaine concentration was obtained with a limit of detection of 0.15 ng/L. Within an overall assay time of 25 minutes, concentrations down to 1 ng/L could be reliably determined in water, oral fluids, and urine, the system possessing a dynamic working range up to 1 mg/L.
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.
Microbial contamination of fuels by fungi and bacteria presents risks of corrosion and fuel system fouling. In this work, a rapid test for the determination of microbial genomic DNA from aqueous fuel extracts is presented. It combines test strips coated with polystyrene core/mesoporous silica shell particles, to the surface of which modified fluorescent molecular beacons are covalently grafted, with a smartphone detection system. In the hairpin loop, the beacons incorporate a target sequence highly conserved in all bacteria, corresponding to a fragment of the 16S ribosomal RNA gene, which is also present to a significant extent in the 18S rRNA gene of fungi, allowing for broadband microbial detection. In the developed assay, the presence of genomic DNA extracts from bacteria and fungi down to ca. 20−50 μg L−1 induced a distinct fluorescence response. The optical read-out was adapted for on-site monitoring by combining a 3D-printed case with a conventional smartphone, taking advantage of the sensitivity of contemporary complementary metal oxide semiconductor (CMOS) detectors. Such an embedded assembly allowed to detect microbial genomic DNA in aqueous extracts down to ca. 0.2−0.7 mg L−1 and presents an important step toward the on-site uncovering of fuel contamination in a rapid and simple fashion.