Extraction and preconcentration of some organophosphorus pesticides in honey samples using an efficient and green pretreatment method followed by HPLC–UV determination

Pesticides are chemical compounds that are intended to control weeds, insects, herbs and pests [1]. In spite of many advantages of using pesticides in the agricultural activities like increase production volume and improve the appearance of grown foods, they can show a serious risk to human health because of either direct exposure or residues in food and drinking water [2, 3]. Organophosphorus pesticides (OPPs) are placed among the mostly used pesticides worldwide. They can reach the food chain and cause a potential threat to the consumers. OPPs can be toxic when they are absorbed by human organisms and may be life threatening because of acetyl–cholinesterase deactivation [4]. So, it is very important to develop convenient analytical methods for the survey of OPP residues in various samples. In this work, an efficient and green sample pretreatment method based on the combination of dispersive solid phase extraction and temperature–induced homogenous liquid–liquid microextraction has been developed for the extraction and preconcentration of some organophosphorus pesticides (parathion–methyl, triazophos, parathion, diazinon, and phoxim) in honey samples before their determination by high performance liquid chromatography–ultraviolet detection. In the proposed method, firstly, the analytes are adsorbed onto a sorbent (C18) dispersed into an aqueous sample by vortexing. Then cyclohexyl amine is used to desorb the analytes from the sorbent. In the next step, the obtained supernatant is mixed with water thermostated at 0 °C to obtain a homogenous solution. This solution is transferred into a heated water bath. During this process solubility of cyclohexyl amine in water is decreased and its produced fine droplets are dispersed in whole of the solution. The produced droplets go up through the solution and collected on top of the solution. Finally, an aliquot of the extractant is taken and injected into the separation system for analysis. Under the optimum conditions, limits of detection and quantification were in the ranges of 0.90–1.75 and 3.0–5.8 ng g–1, respectively. Enrichment factors and extraction recoveries were in the ranges of 148–183 and 59–73%, respectively. The relative standard deviations of the proposed method were ≤ 5% for intra– (n=6) and inter–day (n=4) precisions at a concentration of 25 ng g–1 of each analyte. Finally, the proposed method was successfully applied to the analysis of the selected pesticides in 21 honey samples supplied from local vendors of different origins of West and East Azerbaijan provinces–Iran.