GC/MIP/AED method for pesticide residue determination in fruits and vegetables

This research describes the results of a gas chromatography/microwave induced plasma/atomic emission detection (GC/MIP/AED) method performed on a Hewlett-Packard 5921A system for pesticide residue analysis in fruits and vegetables. A total of 6 experiments were conducted: (1) sensitivity and linearity studies for elements S, P, Cl, and N by analyzing dursban; (2) a study of instrument response to Cl concentration in pesticide molecules; (3) organochlorinated pesticide recoveries; (4) organophosphate pesticide recoveries; (5) carbamate pesticide recoveries; and (6) investigation of metallic pesticides with plictran and vendex as standards. The rank according to sensitivity and linearity was found to be as follows: S-181 greater than P-178 greater than Cl-479 greater than N-174. Instrument response to the concentration of chlorine atoms in the pesticide molecule was linear, with a correlation coefficient of 0.89. Recoveries of organochlorinated pesticides were 91.7-109.3%, with the exception of citrus, whose recovery was affected by coeluting interferences. Organophosphate recoveries were 73.2% or higher, except for the cygon oxygen analog, which degraded in the GC system under all circumstances. Carbamate recoveries were inconsistent quantitatively; however, the information generated from elements N and S were useful for qualitative confirmation of other methods, such as LC postcolumn derivatization analysis. Overall, the GC/MIP/AED method is powerful for qualitative confirmation in pesticide residue analysis. The instrument's capability of acquiring multi-elements (Cl and P) selectively and accurately is an alternative method for organochlorinated and organophosphate pesticide residue analyses. In addition, the GC/MIP/AED system is easy to use, simple to maintain, and its chromatograms can be interpreted by any chromatography analyst without much prior training.