Department of Analytical Chemistry, Nutrition and Food Sciences, IIAA - Institute of Food Analysis and Research, Universidade de Santiago de Compostela . Constantino Candeira S/N, Santiago de Compostela, Spain.
Environ Sci Technol. 2017 Jun 6;51(11):6250-6259. doi: 10.1021/acs.est.6b05135. Epub 2017 May 12.
The presence of persistent and mobile organic contaminants (PMOC) in aquatic environments is a matter of high concern due to their capability of crossing through natural and anthropogenic barriers, even reaching drinking water. Most analytical methods rely on reversed-phase liquid chromatography (RPLC), which is quite limited for the detection of very polar chemicals. Thus, many of these PMOCs may have not been recognized as water pollutants yet, due to the lack of analytical methods capable to detect them. Mixed-mode LC (MMLC), providing the combination of RP and ion-exchange functionalities is explored in this work with a trifunctional column, combining RPLC, anion and cation exchange, which allows the simultaneous determination of analytes with extremely different properties. A nondiscriminant sample concentration step followed by a MMLC-high resolution mass spectrometry method was developed for a group of 37 very polar model chemicals with different acid/base functionalities. The overall method performance was satisfactory with a mean limit of detection of 50 ng/L, relative standard deviation lower than 20% and overall recoveries (including matrix effects) higher than 60% for 54% of model compounds. Then, the method was applied to 15 real water samples, by a suspect screening approach. For those detected PMOC with standard available, a preliminary estimation of concentrations was also performed. Thus, 22 compounds were unequivocally identified in a range of expected concentrations from 6 ng/L to 540 μg/L. Some of them are well-known PMOC, such as acesulfame, perfluorobutanoic acid or metformin, but other novel pollutants were also identified, as for example di-o-tolylguanidine or trifluoromethanesulfonic acid, which had not or were scarcely studied in water so far.
由于持久性和移动性有机污染物 (PMOC) 能够穿透自然和人为屏障，甚至到达饮用水源，因此它们在水生环境中的存在是一个备受关注的问题。大多数分析方法都依赖于反相液相色谱 (RPLC)，但对于检测非常极性的化学物质，它的应用非常有限。因此，由于缺乏能够检测这些化学物质的分析方法，许多 PMOC 可能尚未被视为水污染物。本研究中探索了混合模式液相色谱 (MMLC)，它结合了反相和离子交换功能，使用一种三功能柱，结合 RPLC、阴离子和阳离子交换，能够同时测定具有非常不同性质的分析物。本研究开发了一种非歧视性的样品浓缩步骤，然后采用 MMLC-高分辨质谱法，对一组具有不同酸碱官能团的 37 种非常极性的模型化合物进行了同时测定。该方法的整体性能令人满意，对于 54%的模型化合物，检测限的平均值为 50ng/L，相对标准偏差低于 20%，总回收率（包括基质效应）高于 60%。然后，通过可疑筛查方法，将该方法应用于 15 个实际水样。对于有标准品的检出 PMOC，还进行了浓度的初步估算。因此，在预期浓度范围为 6ng/L 至 540μg/L 内，可明确鉴定出 22 种化合物。其中一些是众所周知的 PMOC，如乙酰磺胺酸、全氟丁酸或二甲双胍，但也鉴定出了一些新型污染物，如邻甲苯基胍或三氟甲磺酸，这些污染物迄今为止在水中的研究很少或尚未进行研究。
