Validation and Application of Combined QuEChERS Extraction With Cartridge Solid Phase Extraction Cleanup for Pesticide Multiresidue Analysis in Some Vegetables by GC-ECD

Abstract

In this work, a sample preparation and analysis method that combines QuEChERS extraction with c-SPE clean-up procedures and GC-ECD analysis method for detection and quantitation of fifteen multi-class pesticide residues in vegetable commodities were validated. The methodology was validated in terms of linearity, precision, and accuracy. The correlation coefficient results were ranged from 0.9949 to 0.9998. The repeatability was ranged from 0.11 to 8.46 % and the obtained limits of detection (LODs) for all investigated pesticides ranged from 0.0003 to 0.0906ng/ml. The validated procedures were then applied in the analysis of target pesticides in eighteen real vegetable samples (tomato, potato, cucumber, and carrot) purchased from the main markets located in Sana'a city (Yemen). The suitability of the proposed method was first verified by spiking vegetable blanks and calculating the accuracy, precision, and LOD for the selected pesticides in each vegetable commodity. For spiked vegetable samples, LODs were between 0.0044 and 2.4100 ng/g. Recoveries' values were between 82.75% and 109.60%, while the relative standard deviation (RSD) did not exceed 10.50 %. The analysis results of the real samples showed that out of eighteen different vegetable samples, only one sample was found clean from target pesticide residues. Six vegetable samples were found to have pesticides lower than the accepted maximum residue limits (MRLs) and eleven vegetable samples were found to have pesticides mostly higher than the accepted MRLs as adopted by the FAO/WHO Codex Alimentations or European Commission.