Evaluation of selected analyte protectant to improve performance of gas chromatographic analysis of pesticide residues

The effectiveness of three analyte protectants, namely, D-sorbitol, 3-ethoxy-1,2- propanediol (ethoxypropanediol) and L-gulonic acid γ-lactone (gulonolactone) in improving peak shape of analytes for better peak sensitivity and quantitation during GC-MS analysis of pesticide residues were evaluated. The use of these analyte protectants were investigated with three pesticide groups i.e. organochlorine (γ-HCH and α-endosulphan), organophosphate (chlorpyriphosmethyl, fenitrothion and prothiophos) and synthetic pyrethroid (bifenthrin, fenpropathrin, cypermethrin and deltamethrin). The analyte protectants were fortified in mixed pesticide standard at a rate of 1 mg/ml prior to GC-MS analysis. Improvement of analytes was seen as peak was enhanced as much as 41% and better separation obtained with application of analyte protectants. These compounds fill in the active sites in the inlet and column of the GC-MS, thus reducing analyte interactions. The ethoxypropanediol seems adequate to provide protection for pesticide during early to mid-eluting process while sorbitol and gulonolactone can be used for mid to late-eluting process. However, a combination of all three analyte protectants will provide better protection