TY - CONF A1 - Riedel, Soraya A1 - Hülagü, Deniz A1 - Bennet, Francesca A1 - Carl, Peter A1 - Flemig, Sabine A1 - Schmid, Thomas A1 - Schenk, Jörg A1 - Hodoroaba, Vasile-Dan A1 - Schneider, Rudolf T1 - Steps Forward in the Application of 3,3’,5,5’- Tetramethylbenzidine (TMB) in Amperometric Assays N2 - Electrochemical methods make great promise to meet the demand for user-friendly on-site devices for monitoring important parameters. Food industry often runs own lab procedures, e.g. for mycotoxin analysis, but it is a major goal to simplify analysis, linking analytical methods with miniaturized technologies. Enzyme-linked immunosorbent assays, with photometric detection of the horseradish peroxidase (HRP) substrate, 3,3’,5,5’-tetramethylbenzidine (TMB), form a good basis for sensitive detection. To provide a straight-forward approach for the miniaturization of the detection step, we have studied the pitfalls of the electrochemical TMB detection. By cyclic voltammetry it was found that the TMB electrochemistry is strongly dependent on the pH and the electrode material. It was found that screen-printed gold electrodes and a highly acidic pH value (pH 1) are well-suited to perform the electrochemical detection of TMB, due to the reversible character of the redox reaction under these conditions. This set-up provides a good signal stability over several measuring cycles, providing the basis for analysing multiple samples. In contrast to this, for carbon screen-printed electrodes, it was found that the signal response has changed after the electrochemical reaction with TMB at pH 1. At a weakly acidic pH value (pH 4), neither with carbon nor with gold electrodes a reproducible electrochemical detection of TMB could be achieved [1]. Based on these findings we created a smartphone-based, electrochemical, immunomagnetic assay for the detection of ochratoxin A and ergometrine in real samples. Therefore, a competitive assay was performed on magnetic beads using HRP and TMB/H2O2 to generate the signal. Enzymatically oxidized TMB was quantified after addition of H2SO4 by amperometry with screen-printed gold electrodes in a custom-made wall-jet flow cell. The results are in good correlation with the established photometric detection method, providing a solid basis for sensing of further analytes in HRP-based assays using the newly developed miniaturized smartphone-based, electrochemical, immunomagnetic assay. T2 - Electrochemistry 2022 CY - Berlin, Germany DA - 28.09.2022 KW - Cylic Voltammetry KW - Immunoassay KW - TMB KW - Amperometry PY - 2022 N1 - Geburtsname von Riedel, Soraya: Höfs, S. - Birth name of Riedel, Soraya: Höfs, S. AN - OPUS4-55876 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Sturm, Heinz A1 - Altmann, Korinna A1 - Braun, Ulrike T1 - Notwendigkeit von (Realistischen) Referenzmaterialien N2 - Die Herstellung von Mikroplastik Referenzmaterialien wird vorgestellt. T2 - Statusfonferenz der BMBF Fördermassnahme "Plastik in der Umwelt" CY - Berlin, Germany DA - 09.04.2019 KW - Ringversuch KW - Mikroplastik KW - Referenzmaterialien PY - 2019 AN - OPUS4-47798 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - DNA based Reference Materials: In Biodosimetry and Pharmaceutical Quality Control N2 - Applications of plasmid DNA base reference materials in dosimetry and pharmaceutical research. T2 - Physical and Chemical Analysis of Polymers seminar CY - Online meeting DA - 29.03.2021 KW - Analytic KW - Certification KW - DNA KW - Dosimetry KW - Homogeneity KW - Quality testing KW - Reference material KW - Referenzmaterialien KW - Stability KW - Dose KW - Radiation KW - Pharmacy KW - Electrohpresis PY - 2021 AN - OPUS4-52361 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin T1 - Reference Materials at BAM N2 - A introduction into reference materials, the certification process and brief over current reference projects at BAM is given. T2 - AK-Postdoc seminar CY - BAM Berlin, Germany DA - 02.02.2021 KW - Referenzmaterialien KW - Reference material KW - Homogeneity KW - Stability KW - Quality testing KW - Analytic KW - DNA KW - Dosimetry KW - Certification PY - 2021 AN - OPUS4-52060 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Altmann, Korinna A1 - Sturm, Heinz A1 - Fischer, D. A1 - Fischer, F. A1 - Ivleva, N. A1 - Witzig, C. A1 - Zumbülte, N. A1 - Braun, U. T1 - Results of the Plastic in the environment comparative test N2 - The talk describes the sturcture and the results of the "plastics in the environment" comparative test of 2019. T2 - Symposium "Challenges of microplastic analysis – Bridging state of the art and policy needs” CY - Online meeting DA - 09.09.2021 KW - Microplastic KW - Comparative test KW - ILC PY - 2021 AN - OPUS4-53236 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wiesner, Yosri A1 - Bednarz, Marius A1 - Braun, Ulrike A1 - Bannick, Claus Gerhard A1 - Ricking, Mathias A1 - Altmann, Korinna T1 - A promising approach to monitor microplastic masses in composts N2 - Inputs of plastic impurities into the environment via the application of fertilizers are regulated in Germany and the EU by means of ordinances. Robust and fast analytical methods are the basis of legal regulations. Currently, only macro- and large microplastic contents (>1 mm) are measured. Microplastics (1–1,000 µm), are not yet monitored. Thermal analytical methods are suitable for this purpose, which can determine the mass content and can also be operated fully automatically in routine mode. Thermal extraction desorption-gas chromatography/mass spectrometry (TED-GC/MS) allows the identification of polymers and the determination of mass contents in solid samples from natural environments. In accordance with the German or European Commission (EC) Fertiliser Ordinance, composting plants should be monitored for microplastic particles with this method in the future. In this context a compost plant was sampled. At the end of the rotting process, the compost was sieved and separated in a coarse (>1 mm) and a fine fraction (<1 mm). The fine fraction was processed using density separation comparing NaCl and NaI as possible salt alternative and screened for microplastic masses by TED-GC/MS with additional validation and quality assurance experiments. With TED-GC/MS total microplastics mass contents of 1.1–3.0 μg/mg in finished compost could be detected with polyethylene mainly. What differs much to the total mass of plastics in the coarse fraction with up to 60 μg/mg, which were visually searched, identified via ATR-FTIR and gravimetrically weighted. KW - Microplastics KW - TED-GC/MS KW - Compost KW - Monitoring KW - Soil PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-586688 DO - https://doi.org/10.3389/fenvc.2023.1281558 SN - 2673-4486 VL - 4 SP - 1 EP - 12 PB - Frontiers Media CY - Lausanne AN - OPUS4-58668 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - You, Zengchao A1 - Weidner, Steffen A1 - Jakubowski, Norbert A1 - Panne, Ulrich T1 - Separation of polystyrene nanoparticles with different coatings using 2D off-line coupling of asymmetrical flow field flow fractionation (AF4) and capillary electrophoresis (CE) N2 - Nowadays, different nanoparticles have been developed for commercial applications. However, since data on toxicity are barely available, their increasing application in cosmetic products, food and their release in the environment might cause severe problems. An accurate separation, identification and characterization of nanoparticles becomes increasingly important1,2. In this presentation, a two-dimensional separation approach based on AF4 and CE was showed and used to separate NPs with similar sizes but different coatings. Standard reference polystyrene NPs having comparable core sizes but different coatings were investigated. Different migration time and profiles were compared. Separation in either method resulted in non-baseline resolved or non-separated peaks. In contrast, two-dimensional coupling of AF4 and CE resulted in clearly separated regions in their 2 D plots in case of 20 and 50 nm particle mixtures, whereas the 100 nm NP mixture could not be separated. Various factors affecting the separation like hydrodynamic diameter or SDS concentration were discussed. Future investigations will be focussed on inorganic NPs with differently charged coatings. There, AF4-CE coupling can be coupled with inductively coupled plasma mass spectrometry (ICP-MS) to enhance the sensitivity of this method. T2 - 6th FFF-MS Tagung CY - Berlin, Germany DA - 22.11.2018 KW - Nanoparticles separation capillary electrophoresis asymmetrcial flow field flow fractionation PY - 2018 AN - OPUS4-47191 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - You, Zengchao A1 - Weidner, Steffen A1 - Jakubowski, Norbert A1 - Meermann, Björn A1 - Panne, Ulrich T1 - Nanoparticles separation using capillary electrophoresis N2 - Nowadays, different nanoparticles have been developed for commercial applications. However, since data on toxicity are barely available, their increasing application in cosmetic products, food and their release in the environment might cause severe problems. An accurate separation, identification and characterization of nanoparticles becomes increasingly important. A common method for nanoparticle separation, which was introduced in 1976 by Giddings, represents asymmetrical field-flow fractionation (AF4). It is a flow based separation method, which can be theoretically used to separate particles range from 1 nm to 50 µm. However, when the particles are smaller than 10 nm, separation with AF4 will become difficult to perform. Because in this case strong separation force, which induces aggregation of particles, should be applied. This will decrease recoveries of analytes and limit its application in accurate quantitative analysis. Capillary electrophoresis (CE) is another well-developed separation technique, in which samples will be separated in relation to their electrophoretic mobility. In recent years, CE has been used to separate different kinds of nanoparticles like, gold colloids or CdSe Quantum dots. However, till now only separation of particles smaller than 50 nm was reported. Because large size distribution of bigger particles will result in strong peak broadening and long separation time. A two-dimensional coupling of AF4 and CE might provide us a new separation method, which can extend the separation ranges of both methods and be a way to characterise particles with large size distributions. T2 - ESAS-CANAS Konferenz CY - Berlin, Germany DA - 21.03.2018 KW - Nanoparticles separation capillary electrophoresis asymmetrcial flow field flow fractionation PY - 2018 AN - OPUS4-47188 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - You, Zengchao A1 - Jakubowski, Norbert A1 - Panne, Ulrich A1 - Weidner, Steffen T1 - Separation of polystyrene nanoparticles with different coatings using 2D off-line coupling of asymmetrical flow field flow fractionation (AF4) and capillary electrophoresis (CE) N2 - The successful off-line coupling of asymmetrical flow field flow fractionation (AF4) and capillary electrophoresis (CE) for Separation of nanoparticles (NPs) with different surface coatings was shown. Two mixtures of polystyrene nanoparticles (PS-NPs) with comparable core sizes (20 nm and 50 nm) but different coatings (no coating/carboxyl-coated) were studied. Separation in either method resulted in non-baseline resolved or non-separated peaks. In contrast, two-dimensional off-line coupling of AF4 and CE resulted in clearly separated regions in their 2 D plots and can obviouly improve separation resolution. T2 - Anakon 2019 CY - Münster, Germany DA - 25.03.2019 KW - Capillary electrophoresis (CE) KW - Nanoparticles with same nominal diameter; surface coating; two-dimensional off-line coupling KW - Asymmetrical flow field flow fractionation (AF4) PY - 2019 AN - OPUS4-47746 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - You, Zengchao A1 - Weidner, Steffen A1 - Jakubowski, Norbert A1 - Panne, Ulrich T1 - Nanoparticles separation using capillary electrophoresis (CE) and asymmerical flow-field flow fractionation (AF4) N2 - Nowadays, different nanoparticles have been developed for commercial applications. However, since data on toxicity are barely available, their increasing application in cosmetic products, food and their release in the environment might cause severe problems. An accurate separation, identification and characterization of nanoparticles becomes increasingly important. A common method for nanoparticle separation, which was introduced in 1976 by Giddings, represents asymmetrical field-flow fractionation (AF4). It is a flow based separation method, which can be theoretically used to separate particles range from 1 nm to 50 µm. However, when the particles are smaller than 10 nm, separation with AF4 will become difficult to perform. Because in this case strong separation force, which induces aggregation of particles, should be applied. This will decrease recoveries of analytes and limit its application in accurate quantitative analysis. Capillary electrophoresis (CE) is another well-developed separation technique, in which samples will be separated in relation to their electrophoretic mobility. In recent years, CE has been used to separate different kinds of nanoparticles like, gold colloids or CdSe Quantum dots. However, till now only separation of particles smaller than 50 nm was reported. Because large size distribution of bigger particles will result in strong peak broadening and long separation time. A two-dimensional coupling of AF4 and CE might provide us a new separation method, which can extend the separation ranges of both methods and be a way to characterise particles with large size distributions. T2 - BAM PhD seminar CY - PhD seminar, Berlin, Germany DA - 22.06.2018 KW - Nanoparticles separation capillary electrophoresis asymmetrcial flow field flow fractionation PY - 2018 AN - OPUS4-47187 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -