Development of an analytical method for the simultaneous determination of the 17 EU Watch List compounds in surface waters: a Spanish case study

Environmental context In 2015, the European Union issued a Watch List of organic pollutants resulting from anthropogenic activities. A major obstacle to controlling these pollutants in the environment is the difficulty of their simultaneous measurement at low concentrations. We developed an analytical method for the simultaneous determination in surface water of the 17 pollutants included in the EU Watch List. Abstract A multi-class method was developed for the simultaneous determination of the 17 organic pollutants included in the EU Decision 2015/495 regarding surface waters. The target analytes were three estrogens, four pharmaceuticals, a food additive, a solar filter and eight pesticides. The target compounds were extracted through solid-phase extraction with Oasis HLB cartridges. Determination was carried out by high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS). All compounds were satisfactorily determined in one single injection, with a chromatographic run time of only 20 min. The limit of detection (LOD) of the proposed method was in the range of 0.08–13 ng L-1. For most of the target compounds, except for 17a-ethinylestradiol, 17ß-estradiol and estrone, the LOD values were equal or below those required by the EU Decision 2015/495. Accuracy was in the range of 69–120 %, whereas inter-day variability was below 20 % in all cases. The validated method was applied to assess the presence of these compounds in Mediterranean surface waters. Samples were collected from 18 sampling sites located in the south of Spain. Up to 14 compounds were detected, among them, the pharmaceutical compounds were the pollutants most frequently detected at concentration levels up to 1158 ng L-1 (diclofenac).