TY - CONF A1 - Hoffmann, Holger T1 - An insight into fractionated environmental water samples to understand matrix effects in immunoassays N2 - N4-acetyl-SMX is the most important cross-reacting compound for the SMX-ELISA with concentrations of 1064 - 2488 ng/L in influent wastewater and 40 - 160 ng/L in effluent wastewater. The ELISAgrams for estrone show less interfering signals than for SMX. ELISAgrams of SMX and estrone display in effluent wastewater more interfering signals than in influent wastewater. T2 - ANAKON CY - Graz, Austria DA - 23.03.2015 KW - Estrone KW - LC-ELISA KW - Matrix effects KW - Sulfamethoxazole PY - 2015 AN - OPUS4-38533 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Frenz, Holger A1 - Gruhn, B. A1 - Dietrich, C. A1 - Lehmann, J. A1 - Krämer, E. A1 - Glaubitz, Steffen A1 - Wimmer, J. A1 - Rehmer, Birgit A1 - Kühn, Hans-Dieter A1 - Breitkreutz, Konrad A1 - Portella, Pedro Dolabella A1 - Hoffmann, E. A1 - Ziebs, Josef T1 - Sphäroguß als Werkstoff für Behälter zur Beförderung, Zwischen- und Endlagerung radioaktiver Stoffe; Untersuchung zu alternativen Eignungsnachweisen - Fachband 3: Werkstoffuntersuchungen, 1989 - 1992 N2 - Gußeisen mit Kugelgraphit und ferritischer bzw. ferritisch-perlitischer Matrix gehören zu einer Werkstoffgruppe, die ausreichende Festigkeiten mit hohen Duktilitäten verbindet. Mit der vorliegenden Arbeit wurden die Kenntnisse über die Zusammenhänge zwischen der chemischen Zusammensetzung, der Gefügeausbildung und den mechanischen Eigenschaften erweitert. Dabei wurden sowohl unterschiedliche Gießverfahren (Sand- und Kokillenguß) in der Herstellung, als auch die Auswirkungen von Umwandlungsprozessen im Gefüge infolge von Wärmebehandlungen diskutiert. Die statistische Auswertung von Einzelergebnissen aus der qualitätssichernden Begutachtung von Lager- und Transportbehältern für radioaktive Stoffe wurden durch mechanische und bruchmechanische Untersuchungen an 24 Werkstoffsorten aus Gußeisen mit Kugelgraphit ergänzt. KW - Eignungsnachweis KW - Endlagerung KW - Lagerbehälter KW - Radioaktiver Stoff KW - Sphäroguß (GGG-40) KW - Transportbehälter KW - Zwischenlagerung PY - 1992 N1 - Das Projekt wurde gefördert vom Bundesminister für Forschung und Technologie (BMFT); Förderkennzeichen: KWA 79052. SP - 1 EP - 178 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-59950 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Holger T1 - Behandlung von Klärwerkswasserproben zur Reduktion von Matrixeffekten bei der Quantifizierung von Sulfamethoxazol mittels Immunoassay (ELISA) N2 - N-Acetyl-SMX, der Kreuzreaktand mit der bisher höchsten bekannten Kreuzreaktivität in diesem SMX-ELISA, kann durch saure Behandlung entfernt werden. Durch Verdünnung der Probe kann die Überbestimmung reduziert werden, besonders für Proben mit hoher Interferenzbelastung (Matrix). T2 - Jahrestagung der Wasserchemischen Gesellschaft CY - Bamberg, Deutschland DA - 02.05.2016 KW - Überbestimmung KW - ELISA KW - Matrixreduktion PY - 2016 AN - OPUS4-35935 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hoffmann, Holger A1 - Knizia, Christian A1 - Kuhne, Maren A1 - Panne, Ulrich A1 - Schneider, Rudolf T1 - LC–ELISA as a contribution to the assessment of matrix effects with environmental water samples in an immunoassay for estrone (E1) N2 - Estrone (E1), a metabolite of the estrogenic hormones 17β-estradiol (β-E2) and 17α-estradiol (α-E2), is itself a potent estrogen which can have a significant impact on the hormonal balance. Due to ist high potential for adverse effects on human health and aquatic life even at pg/L to ng/L levels, its appearance in water should be monitored. E1 has also been considered a marker substance for the presence of other estrogens. This study presents a newly developed direct competitive enzymelinked immunosorbent assay (ELISA) for quantification of E1 in environmental water samples using new monoclonal antibodies. The quantification range of the ELISA is 0.15 μg/L to 8.7 μg/L E1, and the limit of detection is around 60 ng/L for not pre-concentrated water samples. A pre-concentration step after careful selection of suitable phases for SPE was developed, too. The influence of organic solvents and natural organic matter on the ELISA was assessed. The high selectivity of the monoclonal antibody was demonstrated by determining the cross-reactivity against 20 structurally related compounds. For the assessment of matrix effects, a concept (“LC–ELISA”) is thoroughly exploited, i.e., separating complex samples by HPLC into 0.3 min fractions and determination of the apparent E1 concentration. Furthermore, fractions with interferences for nontarget/suspected-target analysis can be assigned. A dilution approach was applied to distinguish between specific interferences (cross-reactants) and non-specific interferences (matrix effects). In the determination of 18 environmental samples, a good agreement of the E1 concentration in the respective fractions was obtained with mean recoveries of 103 % to 132 % comparing ELISA to LC–MS/MS. KW - Validierung KW - Immunoassay KW - Matrixeffekte KW - Abwasser KW - Oberflächenwasser KW - ELISA KW - LC-MS/MS KW - Hormone KW - Endokrine Disruptoren PY - 2018 DO - https://doi.org/10.1007/s00769-018-1351-7 SN - 1432-0517 SN - 0949-1775 VL - 23 IS - 6 SP - 349 EP - 364 PB - Springer CY - Heidelberg AN - OPUS4-46891 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Holger T1 - An insight into the binding affinity of a polyclonal anti-sulfamethoxazole antibody to copuonds in environmental water samples T2 - 9. Interdisziplinäres Doktorandenseminar, Prozessanalytik Chemo- und Biosensoren CY - Berlin DA - 2015-02-22 PY - 2015 AN - OPUS4-32658 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Holger T1 - Evaluation of a polyclonal anti-sulfamethoxazole and a monoclonal anti-estrone antibody in different types of environmental water samples T2 - 15th International Conference on Chemistry and the Environment (EuChems) CY - Leipzig DA - 2015-09-20 PY - 2015 AN - OPUS4-34515 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Holger T1 - Matrixvalidierung von Immunoassays (ELISAs) für Abwasserproben T2 - Wasserchemische Gesellschaft 2015 CY - Schwerin, Germany DA - 2015-05-11 PY - 2015 AN - OPUS4-33645 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hoffmann, Holger T1 - Entwicklung und Anwendung eines Immunoassays (ELISA) zur Quantifizierung von Sulfamethoxazol in Abwasser und Oberflächengewässern N2 - N-Acetyl-SMX ist der Kreuzreaktand mit der bisher höchsten bekannten Kreuzreaktivität in diesem SMX-ELISA. Gemessene SMX-Konzentrationen in Klärwerkszuläufen waren im Bereich von 354-881 ng/L, in Abläufen von 221-421 ng/L und in Oberflächenwasser von 24-202 ng/L. Durch Verwendung einer Auftrennung der Probe in Fraktionen lassen sich störende Interferenzen beseitigen, aber die Probenmesszeit wird deutlich länger. T2 - 2. Wasseranalytisches Seminar (MWAS 2016) CY - Mülheim an der Ruhr, Germany DA - 14.09.2016 KW - Sulfamethoxazole KW - ELISA KW - LC-ELISA KW - Überbestimmung KW - Kreuzreaktand PY - 2016 AN - OPUS4-37383 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kittler, Katrin A1 - Hoffmann, Holger A1 - Lindemann, Franziska A1 - Koch, Matthias A1 - Rohn, S. A1 - Maul, Ronald T1 - Biosynthesis of 15N-labeled cylindrospermopsin and its application as internal standard in stable isotope dilution analysis N2 - Cylindrospermopsin (CYN) is a cyanobacterial toxin associated with human and animal poisonings. Due to its toxicity in combination with its widespread occurrence, the development of reliable methods for selective, sensitive detection and accurate quantification is mandatory. Liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis using stable isotope dilution analysis (SIDA) represents an ideal tool for this purpose. U-[15N5]-CYN was synthesized by culturing Aphanizomenon flos-aquae in Na15NO3-containing cyanobacteria growth medium followed by a cleanup using graphitized carbon black columns and mass spectrometric characterization. Subsequently, a SIDA-LC-MS/MS method for the quantification of CYN in freshwater and Brassica matrices was developed showing satisfactory performance data. The recovery ranged between 98 and 103 %; the limit of quantification was 15 ng/L in freshwater and 50 µg/kg dry weight in Brassica samples. The novel SIDA was applied for CYN determination in real freshwater samples as well as in kale and in vegetable mustard exposed to toxin-containing irrigation water. Two of the freshwater samples taken from German lakes were found to be CYN-contaminated above limit of quantification (17.9 and 60.8 ng/L). CYN is systemically available to the examined vegetable species after exposure of the rootstock leading to CYN mass fractions in kale and vegetable mustard leaves of 15.0 µg/kg fresh weight and 23.9 µg/kg fresh weight, respectively. CYN measurements in both matrices are exemplary for the versatile applicability of the developed method in environmental analysis. KW - Cyanotoxin KW - Quantification KW - Surface water KW - Vegetable plants KW - SIDA KW - HPLC-MS/MS PY - 2014 DO - https://doi.org/10.1007/s00216-014-8026-y SN - 1618-2642 SN - 1618-2650 VL - 406 IS - 24 SP - 5765 EP - 5774 PB - Springer CY - Berlin AN - OPUS4-31566 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Abbas, Ioana M. A1 - Vranic, M. A1 - Hoffmann, Holger A1 - El-Khatib, Ahmed H. A1 - Montes-Bayón, M. A1 - Möller, H. M. A1 - Weller, Michael G. T1 - Investigations of the copper peptide hepcidin-25 by LC-MS/MS and NMR (+) N2 - Hepcidin-25 was identified as the main iron regulator in the human body, and it by binds to the sole iron-exporter ferroportin. Studies showed that the N-terminus of hepcidin is responsible for this interaction, the same N-terminus that encompasses a small copper(II)-binding site known as the ATCUN (amino-terminal Cu(II)- and Ni(II)-binding) motif. Interestingly, this copper-binding property is largely ignored in most papers dealing with hepcidin-25. In this context, detailed investigations of the complex formed between hepcidin-25 and copper could reveal insight into its biological role. The present work focuses on metal-bound hepcidin-25 that can be considered the biologically active form. The first part is devoted to the reversed-phase chromatographic separation of copper-bound and copper-free hepcidin-25 achieved by applying basic mobile phases containing 0.1% ammonia. Further, mass spectrometry (tandem mass spectrometry (MS/MS), high-resolution mass spectrometry HRMS)) and nuclear magnetic resonance (NMR) spectroscopy were employed to characterize the copper-peptide. Lastly, a three-dimensional (3D)model of hepcidin-25with bound copper(II) is presented. The identification of metal complexes and potential isoforms and isomers, from which the latter usually are left undetected by mass spectrometry, led to the conclusion that complementary analytical methods are needed to characterize a peptide calibrant or reference material comprehensively. Quantitative nuclear magnetic resonance (qNMR), inductively-coupled plasma mass spectrometry (ICP-MS), ion-mobility spectrometry (IMS) and chiral amino acid analysis (AAA) should be considered among others. KW - Metalloprotein KW - Peptide KW - Chromatography KW - High pH KW - Mobile phase KW - Metrology KW - Purity KW - Reference material KW - ATCUN KW - Copper KW - Nickel PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-457796 UR - http://www.mdpi.com/1422-0067/19/8/2271 DO - https://doi.org/10.3390/ijms19082271 SN - 1422-0067 VL - 19 IS - 8 SP - 2271, 1 EP - 16 PB - MDPI CY - Basel AN - OPUS4-45779 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Abbas, Ioana M. A1 - Hoffmann, Holger A1 - Montes-Bayón, M. A1 - Weller, Michael G. T1 - Improved LC-MS/MS method for the quantification of hepcidin-25 in clinical samples N2 - Mass spectrometry-based methods play a crucial role in the quantification of the main iron metabolism regulator hepcidin by singling out the bioactive 25-residue peptide from the other naturally occurring N-truncated isoforms (hepcidin-20, -22, -24), which seem to be inactive in iron homeostasis. However, several difficulties arise in the MS analysis of hepcidin due to the sticky character of the peptide and the lack of suitable standards. Here, we propose the use of amino- and fluoro-silanized autosampler vials to reduce hepcidin interaction to laboratory glassware surfaces after testing several types of vials for the preparation of stock solutions and serum samples for isotope dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS). Furthermore, we have investigated two sample preparation strategies and two chromatographic separation conditions with the aim of developing an LC-MS/MS method for the sensitive and reliable quantification of hepcidin-25 in serum samples. A chromatographic separation based on usual acidic mobile phases was compared with a novel approach involving the separation of hepcidin-25 with solvents at high pH containing 0.1% of ammonia. Both methods were applied to clinical samples in an intra-laboratory comparison of two LC-MS/MS methods using the same hepcidin-25 calibrators with good correlation of the results. Finally, we recommend an LC-MS/MS-based quantification method with a dynamic range of 0.5–40 μg/L for the assessment of hepcidin-25 in human serum that uses TFA-based mobile phases and silanized glass vials. KW - HPLC KW - Liquid chromatography KW - Mass spectrometry KW - Silanization KW - Mobile phase KW - Adsorption KW - Peptide losses KW - Recovery KW - Validation KW - Quality control KW - QC KW - Iron disorders KW - Chronic kidney disease KW - Metrology KW - Round robin exercise KW - Basic solvent KW - Peptide analysis PY - 2018 DO - https://doi.org/10.1007/s00216-018-1056-0 SN - 1618-2642 SN - 1618-2650 VL - 410 IS - 16 SP - 3835 EP - 3846 PB - Springer Nature CY - Heidelberg AN - OPUS4-45053 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -