Application of chemometric techniques to the optimization of the solid-phase extraction of 27 pesticides before GC-MIP-AES analysis

Abstract

Determination of heteroelement organic compounds at environmental levels requires highly efficient chromatographic separations and selective and sensitive detection. For this purpose, a capillary gas chromatographic–helium atmospheric pressure microwave-induced plasma atomic emission detection method was developed for the simultaneous determination of 18 organochlorine and nine organophosphorus pesticides in water samples. Monitoring the emission lines for elements such as chlorine, phosphorus and sulfur ensures nearly specific chromatograms for these elements, increasing the selectivity markedly. On the other hand, to allow quantitative recoveries of these pesticides from aqueous samples, the solid-phase extraction (SPE) of the target compounds was optimised using two sequential experimental designs. A 2³ factorial design was initially performed to study the relative importance of three SPE main variables: sample volume, volume and percentage of dichloromethane in the elution solvent. Following this factorial design, a central composite design was used to demonstrate that the SPE conditions can be optimised to obtain the best overall recoveries of the 27 compounds studied. The extraction and determination techniques were applied to the determination of pesticides in waste water samples.