پديدآورندگان :
Kazemian Roya Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz , Farajzadeh Mir Ali mafarajzadeh@tabrizu.ac.ir Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz; , Abbaspour Maryam Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz
چكيده فارسي :
Pesticides are widely used to protect crops and plants from pests and diseases with the objective of increasing agricultural productivity [1]. Since some pesticides are carcinogenic and some can cause dysfunctions in the nervous and reproductive systems, even at low concentrations, they can be extremely harmful to human health [2]. Due to adverse effects of pesticides on both human health and the environment, their monitoring is a necessity. Pesticides are usually determined by gas chromatography, liquid chromatography, or capillary electrophoresis depending on their polarity, volatility, and thermal stability. However, when their concentrations are low, an enrichment step is usually needed before analysis. Sample preparation is one of the most important steps in each chemical analysis. The aim of this challenging and critical step is to prepurify, concentrate, and transfer the analyte into a form that is compatible with the analytical system. Liquid–liquid extraction (LLE) [3] and solid–phase extraction [4], probably, are the most widely used sample preparation methods for pesticide residues analysis. These techniques are time–consuming, expensive and especially relating to LLE, hazardous to health due to high volume of potentially toxic solvents used [5]. In the present study an LLE combined with a new deep eutectic solvent based dispersive liquid–liquid microextraction (DES–DLLME) was proposed for the extraction and preconcentration of some pesticide residues in honey. The DES was synthesized using a hydrogen bond donor (dichloroacetic acid) and a hydrogen bond acceptor (menthol). It was used as an extraction solvent. This method consisted of two steps: (i) extraction of the analytes from honey, and (ii) performing DES–DLLME for enrichment of them. In the first step, the selected analytes in honey were extracted into acetone which were used as a disperser in the following DES–DLLME method. Effect of various experimental parameters on the extraction efficiency were studied and optimized. Under the optimized extraction conditions limits of detection and enrichment factors for the analytes were obtained in the ranges of 0.32–1.2 ng g−1 and 279–428, respectively. The obtained extraction recoveries were between 56 and 86% and the calibration curves were linear in wide ranges with correlation coefficients ≥0.9988. Relative standard deviations were less than 7.0% for intra– (n=6) and inter–day (n=5) precisions (at two concentrations of 10 and 50 ng g−1 of each analyte). Finally, the proposed method was applied on different honey samples and diazinon was determined in one sample at a concentration of 25 ± 3 ng g−1 (n=3).