Deeb Ahmad A, Schmidt Torsten C
Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitaetsstr. 5, 45141, Essen, Germany.
Center for Water and Environmental Research (ZWU), University of Duisburg-Essen, Universitaetsstr. 2, 45141, Essen, Germany.
Anal Bioanal Chem. 2016 Jun;408(16):4219-32. doi: 10.1007/s00216-016-9523-y. Epub 2016 Apr 20.
The presence of organic micropollutants and their transformation products (TPs) from biotic and abiotic processes in aquatic environments is receiving intense public and scientific attention. Yet a suitable sample preparation method that would enable extraction and enrichment of a wide range of such compounds from water is missing. The focus of this paper was to develop an enhanced solid phase extraction (SPE) protocol which enabled isolation of parent compounds and low molecular weight transformation products (that are produced after treatment of water with ozone) from different water matrices. Ten SPE sorbents were evaluated with regard to their ability to extract acidic, neutral, and basic compounds from water at several pH values. Highest recoveries (91-99 %) for all analytes in pure water were obtained by combining strong anion and cation exchangers of two manufacturers in a tandem mode without pH adjustment. Tandem Oasis (MAX+MCX) was finally applied to extract the spiked analytes from tap water, surface water, and several wastewater samples. The efficiency of the used SPE procedure was examined using an optimized liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method using multiple reaction monitoring (MRM) mode. The occurrence of some of the investigated TPs in environmental water matrices was proven for the first time in this study. Method quantification limits (MQLs) for all compounds ranged from 3.7 to 15.3 ng/L in all matrices. Recoveries (%RE) were between 90 and 110 %. Intraday and interday precision, expressed as relative standard deviation, varied from 0.7 to 5.9 % and 1.8 to 10.3 %, respectively. Matrix effect (%ME) evaluation demonstrated that even complex sample matrices did not show significant ion suppression or enhancement. The applicability of the method was shown during two sampling campaigns at Ruhr river and a wastewater treatment plant (WWTP) equipped with an ozonation step after regular biological treatment. The parent compounds were found in all water matrices at concentrations ranging between low nanogram per liter and low microgram per liter. Concentration levels of the detected TPs were in the lower nanogram per liter range. Their concentrations increased after ozonation of treated wastewater but decreased substantially after a polishing biological treatment in the final effluent and in the receiving surface water; thus demonstrating that occurrence at critical concentrations in aquatic ecosystems is rather unlikely.
水生环境中有机微污染物及其通过生物和非生物过程产生的转化产物（TPs）的存在正受到公众和科学界的密切关注。然而，目前缺少一种合适的样品制备方法，能够从水中提取和富集多种此类化合物。本文的重点是开发一种改进的固相萃取（SPE）方案，该方案能够从不同的水基质中分离母体化合物和低分子量转化产物（这些产物是在用臭氧处理水后产生的）。对10种SPE吸附剂在几个pH值下从水中提取酸性、中性和碱性化合物的能力进行了评估。在不调节pH值的情况下，通过串联两种制造商生产的强阴离子和阳离子交换剂，在纯水中获得了所有分析物的最高回收率（91-99%）。最终应用串联的Oasis（MAX+MCX）从自来水、地表水和几个废水样品中提取加标分析物。使用优化的液相色谱-电喷雾电离-串联质谱（LC-ESI-MS/MS）方法，采用多反应监测（MRM）模式，对所使用的SPE程序的效率进行了检测。本研究首次证实了环境水基质中一些被研究的TPs的存在。所有化合物在所有基质中的方法定量限（MQLs）范围为3.7至15.3 ng/L。回收率（%RE）在90%至110%之间。以相对标准偏差表示的日内和日间精密度分别在0.7%至5.9%和1.8%至10.3%之间变化。基质效应（%ME）评估表明，即使是复杂的样品基质也没有显示出明显的离子抑制或增强。在鲁尔河和一个在常规生物处理后配备臭氧化步骤的污水处理厂（WWTP）进行的两次采样活动中，展示了该方法的适用性。在所有水基质中都发现了母体化合物，其浓度范围在每升低纳克到低微克之间。检测到的TPs的浓度水平在每升低纳克范围内。经过处理的废水臭氧化后，它们的浓度增加，但在最终出水和受纳地表水经过抛光生物处理后大幅下降；因此表明在水生生态系统中以临界浓度出现的可能性相当小。
