Simultaneous extraction of trace organophosphorous pesticides from plasma sample by automated solid phase extraction and determination by gas chromatography coupled with pulsed flame photometric detector

The purpose of our work was to develop a simple and efficient analytical method for simultaneous determination of different species of organic phosphorus pesticides from plasma sample by using automated solid phase extraction (SPE) and gas chromatography/pulsed flame photometric detector (GC/PFPD) as a diagnostic tool. Firstly, the developed extraction method was validated using 5 certified reference materials; then, it was applied to plasma sample. Such factors as the category and volume of wash and elution solvent were examined separately. Among these factors, the category of elution solvent is most important. Hexane–acetone (50:50, v/v) seems to be the best choice for it. The eluent was evaporated on a nitrogen stream at room temperature and redissolved by acetone. 1 μL of aliquots was chromatographed on GC/PFPD. Response versus the amount of pesticides injected ranging from 0.05 to 2 ng showed a good linearity. The detection limits were 0.01 ng for dimethoate, 0.03 ng for methyl-parathion and malathion, 0.04 ng for terbufos and 0.02 ng for parathion. Extraction recoveries range from 84.3% to 109.1%.This extraction method for multispecies analysis incorporates many benefits in terms of speed, low solvent use, accuracy of measurement, sensitivity, relative simplicity, as well as the time saving and convenience of multiple species measurement through sample preparation and analysis as an integrated step.