TY - JOUR A1 - Martínez, N.A. A1 - Pereira, S.V. A1 - Bertolino, F.A. A1 - Schneider, Rudolf A1 - Messina, G.A. A1 - Raba, J. T1 - Electrochemical detection of a powerful estrogenic endocrine disruptor: ethylestradiol in water samples through bioseparation procedure N2 - The synthetic estrogen ethinylestradiol (EE2) is an active component of oral contraceptives (OCs), considered as an endocrine disrupting compound (EDC). It is excreted from humans and released via sewage treatment plant effluents into aquatic environments. EDCs are any environmental pollutant chemical that, once incorporated into an organism, affects the hormonal balance of various species including humans. Its presence in the environment is becoming of great importance in water quality. This paper describes the development of an accurate, sensitive and selective method for capture, preconcentration and determination of EE2 present in water samples using: magnetic particles (MPs) as bioaffinity support for the capture and preconcentration of EE2 and a glassy carbon electrode modified with multi-walled carbon nanotubes (MWCNTs/GCE) as detection system. The capture procedure was based on the principle of immunoaffinity, the EE2 being extracted from the sample using the anti-EE2 antibodies (anti-EE2 Ab) which were previously immobilized on MPs. Subsequently the analyte desorption was done employing a sulfuric acid solution and the determination of the EE2 in the pre-concentrated solution was carried out by square wave voltammetry (SWV). This method can be used to determine EE2 in the range of 0.035–70 ng L-1 with a detection limit (LOD) of 0.01 ng L-1 and R.S.D. < 4.20%. The proposed method has been successfully applied to the determination of EE2 in water samples and it has promising analytical applications for the direct determination of EE2 at trace levels. KW - Magnetic particles KW - Bioseparation KW - Ethinylestradiol KW - Electrochemistry KW - Immunoassay KW - Elektrochemischer Sensor KW - Endokrine Disruptoren KW - Hormone KW - Ethinylestradiol KW - EE2 KW - Östrogene PY - 2012 DO - https://doi.org/10.1016/j.aca.2012.02.033 SN - 0003-2670 SN - 1873-4324 SN - 0378-4304 VL - 723 SP - 27 EP - 32 PB - Elsevier CY - Amsterdam AN - OPUS4-25656 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Martínez, N.A. A1 - Schneider, Rudolf A1 - Messina, G.A. A1 - Raba, J. T1 - Modified paramagnetic beads in a microfluidic system for the determination of ethinylestradiol (EE2) in river water samples N2 - In this work, we have developed and characterized a novel microfluidic immunoassay methodology for rapid and sensitive quantification of ethinylestradiol (EE2) in river water samples. The detection of EE2 was carried out using a competitive direct immunoassay method based on the use of anti-EE2 polyclonal antibodies immobilized on magnetic microspheres 3-aminopropyl-modified manipulated for an external removable magnet. The EE2 present in the water sample was allowed to compete with EE2-horseradish peroxidase (HPR) conjugated for the immobilized anti-EE2 antibody. The HPR, in the presence of hydrogen peroxide (H2O2) catalyzes the oxidation of catechol (Q) whose back electrochemical reduction was detected on gold electrode at 0.0 V. The response current obtained from the product of enzymatic reaction is inversely proportional to the amount of EE2 in the water sample. The electrochemical detection can be done within 1 min and total assay time was 30 min. The calculated detection limits for electrochemical detection and the ELISA procedure are 0.09 and 0.32 ng L-1 respectively and the intra- and inter-assay coefficients of variation were below 5.8%. Our electrochemical immunosensor showed higher sensitivity and lower time consumed than the standard spectrophotometric detection ELISA method, which shows the potential for assessment of EE2 in river water samples. KW - Enzyme immunoassays KW - Ethinylestradiol KW - Paramagnetic beads KW - Horseradish peroxidase KW - Microfluidic KW - Flow injection analysis PY - 2010 DO - https://doi.org/10.1016/j.bios.2009.10.031 SN - 0956-5663 SN - 1873-4235 VL - 25 IS - 6 SP - 1376 EP - 1381 PB - Elsevier CY - Barking, Essex, UK AN - OPUS4-22188 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nusser, K. A1 - Mosbauer, T. A1 - Schneider, G.J. A1 - Brandt, K. A1 - Weidemann, Gerd A1 - Goebbels, Jürgen A1 - Riesemeier, Heinrich A1 - Göritz, D. T1 - Silica dispersion in styrene butadiene rubber composites studied by synchrotron tomography N2 - By means of synchrotron X-ray computed tomography, model composites consisting of silica and styrene–butadiene rubber were studied with a very high spatial resolution. By our analysis technique we were able to determine the nano- and micro dispersion from the experimental results by our numerical analysis. These results are discussed with respect to crucial advantages of the generically 3-dimensional tomography technique as compared to 2-dimensional methods. Our quantitative analysis of the 3d images demonstrates that in the case of our model composites the filler dispersion is good, independent on the filler concentration. Our new 3-dimensional results evidence that considering only 2-d pictures may lead to ambiguities that can lead to wrong conclusions. KW - X-ray tomography KW - Silica KW - Styrene butadiene rubber KW - Dispersion PY - 2012 DO - https://doi.org/10.1016/j.jnoncrysol.2011.10.009 SN - 0022-3093 VL - 358 IS - 3 SP - 557 EP - 563 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-26105 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -