Trace level determination of insecticide using gas chromatography, and the application for residual monitoring in local Syrian vegetables

We have developed a new extraction and purification method for high sensitive determination of four pesticides, Demethoate (Di), Chlorpyrifos-ethyl (CPE), Deltamethrin (Del) and Cypermethrin (Cyp) from vegetables. The method involves the extraction of samples with acetone and Ethylacetate:Hexane (95:5,v/v) mixture, purification using Florisil cartridges at optimum eluting ratio of 5% acetone in hexane, then followed by gas chromatography using electron capture detection (ECD). Under the optimized condition, the recovery of the pesticides from vegetables reach the range of (80–112%) with RSD% ⩽ 5% ( n = 3), the limit of detection for Di, CPE, Cyp, and Del, were 1, 0.96, 1.3, and 1.9 ng mL −1 , and the limit of quantification was 3.3, 2.9, 3.9, and 5.8 ng mL −1 , respectively. This analytical procedure was characterized with high accuracy and acceptable sensitivity to meet the requirements for monitoring pesticides in vegetables. The method was applied successfully for the determination of pesticides in some local vegetable contamination.