Fast and Selective Determination of Pesticides in Water by Automated On-Line Solid Phase Extraction Liquid Chromatography Tandem Mass Spectrometry

An automated on line-solid phase extraction (SPE) liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of 17 polar pesticides in water. Minimizing sample pretreatment and using a fast chromatographic separation, the method allowed a sample to be processed in 15 minutes. The MS analysis was performed by Data Dependent Acquisition, using the triggered Multiple Reaction Mode function that provided analyte confirmation, thus enhancing selectivity without compromising sensitivity. In fact, the optimized method enabled the determination of the considered pesticides at the ultratrace level, with detection limits in the range 0.07-1.65ng/L (propazine and atrazine-desisopropyl, respectively); the only exception was linuron that showed a slightly higher detection limit (12.2ng/L). The optimized method was then applied to real water samples; five pesticides were determined in river water, in the range 1.17-14.2ng/L, while four were measured in drinking water, in the range 0.91-2.25ng/L.