PESTICIDE RESIDUES ANALYSIS IN POTATOES BY GAS CHROMATOGRAPHY

This paper describes a gas-chromatography with electron capture detection (GC-ECD) method for determination of some pesticides in potato samples. The extraction of the pesticides was carried out by solid-liquid extraction with clean-up by precipitation at low temperature, without additional steps for removal of interferences. The method requires 3 g of potato and an extraction mixture (6.5 mL acetonitrile, 1.0 mL water and 2.5 mL ethyl acetate) that was established by experimental design. The method was efficient with recoveries of 93.8% for chlorpyrifos, 94.4% for lambda-cyhalothrin, 82.1% for cypermethrin and 97.9% for deltamethrin. The quantification limits were 18.7 to 26.4 mu g kg(-1) for the four pesticides. The parameters evaluated in the process of validation, such as selectivity, detection limit, quantification limit, linearity, precision and accuracy, indicated that the methodology is efficient for extraction of the studied pesticides from potatoes. Furthermore, the method was simple, easy to execute, and used only small quantities of organic solvent. The optimized SLE-LTP methodology was applied for the analysis of potatoes randomly purchased from local retail stores and potato samples from a crop treated with commercial insecticide products containing the active ingredients chlorpyrifos and cypermethrin.