ONLINE COUPLING OF SOLID-PHASE EXTRACTION TO GAS-CHROMATOGRAPHY WITH MASS-SPECTROMETRIC DETECTION TO DETERMINE PESTICIDES IN WATER

A group of pesticides with different chemical structures was determine d in water by on-line coupling of solid-phase extraction to gas chroma tography with mass spectrometric detection through an on-column interf ace. A 10 mmx2 mm I.D. precolumn packed with PLRP-S was selected for t he solid-phase extraction process. The parameters affecting the transf er of the analytes from the precolumn to the GC system (e.g. flow-rate , temperature and solvent vapor exit time) were optimized. An organic modifier was added to the sample before the extraction process to avoi d adsorption problems. The use of the MS detector under selected ion m onitoring acquisition enabled the analytes to be quantified at sub mic rogram-per-litre levels preconcentrating only 10 mi of sample, and the Limits of detection (S/N=3) were between 2 and 20 ng l(-1). The metho d was applied to the determination of the pesticides in tap and river water, and molinate was determined in Ebro river water. (C) 1998 Elsev ier Science B.V. All rights reserved.