Determination of 48 pesticides and their main metabolites in water samples by employing sonication and liquid chromatography–tandem mass spectrometry

In this work, a rapid and sensitive analytical multiresidue method has been developed for the simultaneous determination of 48 pesticides and 19 metabolites in waters (tap, leaching and sewage), using liquid chromatography–tandem mass spectrometry (LC–MS/MS) with triple quadrupole in selected reaction monitoring (SRM) mode. The procedure involves initial single phase extraction of samples with acetonitrile by sonication, followed by liquid–liquid partition aided by “salting out” process using NaCl. Matrix influence on recoveries was evaluated for the three waters. More than 50% of the compound presented very low signal suppression. The method presents good linearity over the range assayed 10–500 μg L−1 and the most frequent detection limits was 0.05 ng mL−1. The average recovery by the LC–MS/MS method obtained for these compounds varied from 74.6 to 111.2% with a relative standard deviation between 2.5 and 8.9%. The proposed method was used to determine pesticides levels in leaching water samples from 5 lysimeters from an experimental greenhouse located in Murcia.