Applications of solid-phase microextraction (SPME) in the determination ofresidues of certain herbicides at trace levels in environmental samples

A new analytical procedure based on solid-phase microextraction (SPME) has been developed for the determination of residues of eight selected herbicid es: trifluralin, butachlor, pretilachlor, metolachlor, atrazine, acetochlor , alachlor, and fluroxypyr-meptyl, in ground water samples. Carbowax diviny lbenzene was used for SPME of the herbicides. Quantification was done at eq uilibrium. Various parameters. such Lis. effect of pH, ionic strength, humi c acid content and exposure time of fiber, were investigated to find the ex traction efficiency. The linearity was determined. The method was found sui table for the determination of residues,of herbicides Lit concentration lev els from 5 to 20 ng L-1. The relative standard deviation of the detection l imits were calculated, The humic acid content was found to interfere more s ignificantly in the determination of residues. An ionic chloride strength. in terms of sodium chloride, of up to 10% did not have any significant impa ct on the determination. Furthermore, there was an enhanced sensitivity of detection up to pH 3.0. The method was applied to the analysis of the resid ue contents of the pesticides under investigation in real ground water samp les collected from susceptible places. The results when compared with the s tandard methods published in the literature showed no significant deviation in their quantification and the values were comparable.