Applications of solid-phase microextraction (SPME) in the determination of residues 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 herbicides: trifluralin, butachlor, pretilachlor, metolachlor, atrazine, acetochlor, alachlor, and fluroxypyr-meptyl, in ground water samples. Carbowax divinylbenzene was used for SPME of the herbicides. Quantification was done at equilibrium. Various parameters, such as, effect of pH, ionic strength, humic acid content and exposure time of fiber, were investigated to find the extraction efficiency. The linearity was determined. The method was found suitable for the determination of residues of herbicides at concentration levels from 5 to 20 ng L-1. The relative standard deviation of the detection limits were calculated. The humic acid content was found to interfere more significantly in the determination of residues. An ionic chloride strength, in terms of sodium chloride, of up to 10% did not have any significant impact 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 residue contents of the pesticides under investigation in real ground water samples collected from susceptible places. The results when compared with the standard methods published in the literature showed no significant deviation in their quantification and the values were comparable.
Ramesh
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Department of Pesticide Chemistry, Fredrick Institute of Plant Protection and Toxicology, (FIPPAT), Padappai, Chennai 601 301, Tamil Nadu, India. raamesh_a@hotmail.com
Ravi
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PE
D002623:Chemistry Techniques, Analytical / Q000379:methods; D004784:Environmental Monitoring / Q000379:methods*; D006540:Herbicides / Q000032:analysis*; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D012680:Sensitivity and Specificity; D012989:Soil Pollutants / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*
D006540:Herbicides; D006812:Humic Substances; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical