Extraction of diazinon and chlorpyrifos pesticides in some vegetables using magnetic@chitosan@SNW-۱ followed with QECHERS method

Extra residual amounts of organophosphorus pesticides (OPPs) in the body of the living organisms hve toxic effect on the central nervous system which can lead to paralysis, suffocation,۲or even death. Maximum residue levels (mg kg-۱) of diazinon and chlorpyrifos in the Cucumber, Celery, and Zucchini vegetables are ۰.۰۱ mg kg-۱. Therefore, measurement of in OPPs in agriculture samples is essential. High porosity and specific surface area of covalent organic frameworks (COFs) make them suitable compounds in extraction of the analytes. Also schiff base network-۱ (SNW-۱) can make interactions with various analytes by H – bonding interaction, π-π interaction with nitrogen atoms and Pi. On the other hand, there are amines and hydroxyl groups in the linear structure of chitosan (CS) which cause this biopolymer to make suitable interactions with various molecules. In this method, a novel and green magnetic nanocomposite (M-CS-SNW-۱ nanocomposite) was synthesized and used for extraction and preconcentration of diazinon and chlorpyrifos pesticides from the vegetable samples. The QuEChERS method was applied for clean-up and simplify the complex matrix of the real examples before analysis. Separation and determination of pesticides were done by GC-FID and GC-MS instruments. The optimization parameters such as pH, sorbent amount, adsorption time, desorption type, desorption time, desorption eluent, eluent volume, and sample volume were investigated. Under optimum conditions analytical parameters of the method including limit of detection = ۰.۰۰۸ and ۰.۰۱ μg L-۱, linear range = ۰.۰۴ -۵۰۰ and ۰.۰۷ -۵۰۰ μg L-۱, relative standard deviation (C = ۸۰ μg L-۱, n = ۴) = ۲.۳ and ۴.۷, and enrichment factor = ۶۵ and ۲۸۳ were obtained for diazinon and chlorpyrifos, respectively. The relative recoveriesin real samples confirm the efficiency of the present method for determination of OPPs pesticides in vegetable samples.