Baldofski Stefanie, Hoffmann Holger, Lehmann Andreas, Breitfeld Stefan, Garbe Leif-Alexander, Schneider Rudolf J
Bundesanstalt für Materialforschung und -prüfung (BAM), 12205 Berlin, Germany; Technische Universität Berlin, 10623 Berlin, Germany.
Bundesanstalt für Materialforschung und -prüfung (BAM), 12205 Berlin, Germany; Humboldt-Universität zu Berlin, 10099 Berlin, Germany.
J Environ Manage. 2016 Nov 1;182:612-619. doi: 10.1016/j.jenvman.2016.08.023. Epub 2016 Aug 18.
Bile acids are promising chemical markers to assess the pollution of water samples with fecal material. This study describes the optimization and validation of a direct competitive enzyme-linked immunosorbent assay for the bile acid isolithocholic acid (ILA). The quantification range of the optimized assay was between 0.09 and 15 μg/L. The assay was applied to environmental water samples. Most studies until now were focused on bile acid fractions in the particulate phase of water samples. In order to avoid tedious sample preparation, we undertook to evaluate the dynamics and significance of ILA levels in the aqueous phase. Very low concentrations in tap and surface water samples made a pre-concentration step necessary for this matrix as well as for wastewater treatment plant (WWTP) effluent. Mean recoveries for spiked water samples were between 97% and 109% for tap water and WWTP influent samples and between 102% and 136% for WWTP effluent samples. 90th percentiles of intra-plate and inter-plate coefficients of variation were below 10% for influents and below 20% for effluents and surface water. ILA concentrations were quantified in the range of 33-72 μg/L in influent, 21-49 ng/L in effluent and 18-48 ng/L in surface water samples. During wastewater treatment the ILA levels were reduced by more than 99%. ILA concentrations of influents determined by ELISA and LC-MS/MS were in good agreement. However, findings in LC-ELISA experiments suggest that the true ILA levels in concentrated samples are lower due to interfering effects of matrix compounds and/or cross-reactants. Yet, the ELISA will be a valuable tool for the performance check and comparison of WWTPs and the localization of fecal matter input into surface waters.
胆汁酸是评估水样受粪便物质污染的很有前景的化学标志物。本研究描述了针对胆汁酸异石胆酸（ILA）的直接竞争酶联免疫吸附测定法的优化和验证。优化后的测定法的定量范围为0.09至15μg/L。该测定法应用于环境水样。到目前为止，大多数研究都集中在水样颗粒相中的胆汁酸组分。为了避免繁琐的样品制备，我们着手评估水相中ILA水平的动态变化及其意义。自来水和地表水样品中的浓度非常低，因此对于这种基质以及污水处理厂（WWTP）的出水而言，预浓缩步骤是必要的。加标水样的平均回收率，自来水和污水处理厂进水样品为97%至109%，污水处理厂出水样品为102%至136%。进水的板内和板间变异系数的第90百分位数低于10%，出水和地表水低于20%。进水的ILA浓度定量范围为33 - 72μg/L，出水为21 - 49ng/L，地表水样品为18 - 48ng/L。在废水处理过程中，ILA水平降低了99%以上。通过酶联免疫吸附测定法（ELISA）和液相色谱 - 质谱联用（LC - MS/MS）测定进水的ILA浓度结果吻合良好。然而，液相色谱 - ELISA实验结果表明，由于基质化合物和/或交叉反应物的干扰作用，浓缩样品中的真实ILA水平较低。不过，ELISA将是用于污水处理厂性能检查和比较以及确定粪便物质排入地表水位置的有价值工具。
