Control of Organophosphorus Pesticides Residues in Honey Samples Using a Miniaturized Tandem Preconcentration Technique Coupled with High Performance Liquid Chromatography

Abstract

Background : In the present work, a miniaturized sample preparation method based on combination of dispersive solid phase extraction and temperature–induced homogenous liquid–liquid microextraction has been proposed for the extraction and preconcentration of some organophosphorus pesticides (parathion–methyl, triazophos, parathion, diazinon, and phoxim) from honey samples prior to their analysis by high performance liquid chromatography–ultraviolet detection. Methods: In this method, initially the analytes were adsorbed onto a sorbent (C18) and then desorbed by the use of cyclohexyl amine as an eluent. In the next step, the eluent was mixed with water thermostated at 0 °C to obtain a homogenous solution. By increasing the temperature, the solubility of cyclohexyl amine in water was decreased and led to formation of dispersed fine droplets in the whole of solution. These droplets go up through the solution and collected on top of the solution. Finally, an aliquot of the organic phase was sucked in a microsyringe and injected into the separation system for analysis. Results: Under the optimum experimental conditions, limits of detection and quantification were calculated to be in the ranges of 0.90–1.75 and 3.0–5.8 ng g–1 in honey samples, respectively. Enrichment factors and extraction recoveries were in the ranges of 148–183 and 59–73%, respectively. The relative standard deviations varied from 2–4% and 4–5% for intra– (n = 6) and inter–day (n = 4) precisions, respectively. Conclusion: The suggested approach was satisfactorily utilized to the analysis of 21 honey samples. The proposed miniaturized tandem sample pretreatment method enhanced the sensitivity of the instrumental analysis.