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QuEChERS Method Validation and Analysis of Pesticides in Gas Chromatography Electron Capture Detector

A. HARINATHA REDDY , N. B. L PRASAD and K. LAKSHMI DEVI

A gas chromatography (GC) electron capture detector (ECD) method was developed and validated for the determination of the residues of 33 pesticides in vegetables recovered from the developed method been validated for the extraction of pesticides of various chemical classes from vegetables such as tomato and brinjal. A mixture of 33 pesticides amenable to gas chromatography (GC) were quantitatively recovered from spiked tomato and brinjal, determined using gas chromatography-electron capture detector. The sample preparation approach is known as QuEChERS, which stands for “quick, easy, cheap, effective, rugged and safe”. As expected, the results are excellent and showed overall average of 98% recoveries with 10% RSD. The method involved extraction with acetonitrile, liquid-liquid partition with addition of NaCl followed by MgSO4 and primary secondary amine (PSA) and the analyses were carried out with GC–ECD equipment. It was a rapid, simple and cost effective procedure. The spiking levels for the recovery experiments were 0.1, 0.5 mg Kg-1 for GC–ECD analyses. Adequate pesticide quantification and identity confirmation were attained, even at the lowest concentration levels, considering the high signal-tonoise ratios, the very good accuracies and precisions, as well as the good matches between the observed ion ratios. Mean recoveries of Organo chlorines (OCs) in tomato varied from 80.50-92.20%, in brinjal varied from 78.8-89.9% and Organo phosphates (OPs) in mean recoveries of tomato varied from 75.30- 92.50% and brinjal varied from 76.7-91.1%. Mean recoveries of SYNTHATIC pyrethroids (SPs) in tomato varied from 70.40-92.30% and brinjal varied from 73.3-90.5% and relative standard deviations (RSD) were generally below 10% (4.3% on average). Based on these results, the methodology has been proven to be highly efficient and robust and thus suitable for monitoring the MRL compliance of a wide range of commodity/pesticide combinations.