Development and validation of gas chromatography with electron capture detection method using QuEChERS for pesticide residue determination in cucumber.

A modified quick, easy, cheap, efficient, rugged, and safe (QuEChERS) method coupled to gas chromatography with electron capture detection was developed for the simultaneous determination of selected electronegative pesticides, namely, chlorpyrifos-methyl (1), chlorpyrifos (2), quinolphos (3), profenofos (4), myclobutanil (5), ethion (6), fenpropathrin (7), and cypermethrin (8), in vegetables with high water content. The selected compounds and some of their metabolites have even been found in human body fluids. In addition, some of them are known or suspected carcinogens according to the World Health Organization. Extraction and cleanup parameters were optimized; thus, the original QuEChERS method was modified to minimize solvent usage by making the study eco-friendly. The developed method was validated for selectivity, specificity, linearity, precision, and accuracy using SANTE guidelines. Calibration curves showed good linearity (r > 0.99) within the test range. Precision was evaluated by intra- and inter-day experiments with an acceptable range of less than 20.0% of relative standard deviation. Recovery was evaluated at limit of quantification and was found to be in the range of 70-120%, with relative standard deviations lower than 4.21%. The proposed method is applicable for detection and monitoring of selected pesticides in one run not only in fruits and vegetables with high water content but also in samples containing large quantities of pigments/dyes.