Comparative study using ECD, NPD, and MS/MS chromatographic techniques in the determination of pesticides in wetland waters

Several pesticides widely used to control weeds in vegetables have been determined in wetland water from Almeria, a predominantly agricultural area on the Southeast of Spain. Analysis of the pesticides was performed by gas chromatography (GC) with electron capture detection (ECD), nitrogen phosphorus detection (NPD) and mass spectrometry in tandem (MS/MS) mode, after a preconcentration step of the samples with C-18 cartridges. Recovery, precision, linear range, detection limit (LOD) and quantitation limit (LOQ) for each pesticide was calculated. Important advantages of MS/MS over ECD and NPD to determine pesticides quantitatively at high selectivity in complex matrices are also presented. The most commonly encountered pesticide was fenamiphos, while the ones found at higher concentration levels were metalaxyl and malathion.