Gouri Satpathy¹, Yogesh Kumar Tyagi^1,, Rajinder Kumar Gupta²

The Quick Easy Cheap Effective Rugged and Safe (QuEChERS) multiresidue method has been validated for the extraction of 82 pesticides belonging to various chemical classes from grapes and pomegranate (commodities with high sugar and low lipid contents). A mixture of 82 pesticides amenable to gas chromatography (GC) was quantitatively recovered from spiked grapes and pomegranate and determined using gas chromatography-tandem mass spectrometry (GC-MS/MS). The method employed involved initial extraction in a water/ethyl acetate system, an extraction/partitioning step after the addition of salt, and a cleanup step utilizing dispersive solid-phase extraction (d-SPE); this combination ensured that it was a rapid, simple and cost-effective procedure. The method setup is streamlined with the new software approach of Compound Based Scanning (CBS). The matrix-matched calibration results have demonstrated good reproducibility, robustness and linearity. The spiking levels for the recovery experiments were 0.005, 0.01 and 0.1 mg kg^-1 for GC-MS/MS analyses. Adequate pesticide quantification and identity confirmation were attained, even at the lowest concentration levels, considering the high signal-to-noise ratios, the very good accuracies and precisions, as well as the good matches between the observed ion ratios. Mean recoveries mostly ranged between 70 and 110 % (91% on average), and RSD were generally below 12% (7.3% on average). The use of analyte protectants during GC analysis was demonstrated to provide a good alternative to the use of matrix-matched standards to minimize matrix-effect-related errors. For all compounds LODs were 0.001 to 0.005 mgkg^-1 and LOQs were 0.005 to 0.020 mgkg^-1. Correlation coefficients of the calibration curves were >0.991. Based on these results, the methodology has been proven to be highly efficient and robust and thus suitable for monitoring the Maximum Residual Limit (MRL) compliance of a wide range of commodity/pesticide combinations.

grapes, pomegranate, pesticides, QuEChERS, method validation, GC-MS/MS