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 det ermined in wetland water from Almeria, a predominantly agricultural area on the Southeast of Spain. Analysis of the pesticides was performed by gas ch romatography (GC) with electron capture detection (ECD), nitrogen phosphoru s detection (NPD) and mass spectrometry in tandem (MS/MS) mode, after a pre concentration 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 t o determine pesticides quantitatively at high selectivity in complex matric es are also presented. The most commonly encountered pesticide was fenamiph os, while the ones found at higher concentration levels were metalaxyl and malathion.