Broad-spectrum determination of pesticides in groundwater by gas chromatography with electron capture detection, nitrogen-phosphorus detection, and tandem mass spectrometry

Gas chromatography with electron capture detector (ECD), nitrogen-phosphoru s detector (NPD), and tandem mass spectrometry (MS/MS) was used to identify 36 pesticides, widely used to control various pest and diseases in vegetab les, in water after a preconcentration step on C-18 cartridges. The recover ies obtained ranged from 70 to 135% at a fortification level of 100 ng/L wi th relative standard deviations of < 36.2%. The limits of detection and qua ntitation were less than or equal to 48 and less than or equal to 160 ng/L, respectively. Important advantages of MS/MS over ECD and NPD in the determ ination of pesticides are also presented. The proposed analytical methodolo gy was applied to the determination of pesticides in groundwater samples fr om an agricultural area, the Campo de Dalias (Almeria, Spain). The most fre quently encountered pesticides were endosulfan sulfate and metalaxyl, where as the pesticide found at the highest concentration was fenamiphos.