Combining of modified QuEChERS and dispersive liquid–liquid microextraction as an efficient sample preparation method for extraction of acetamiprid and imidacloprid from pistachio samples

Abstract

In this research, for the first time, the QuEChERS was combined with the dispersive liquid–liquid microextraction based on deep eutectic solvent (QuEChERS-DES-DLLME). The method was developed for efficient extraction, clean-up and preconcentration of acetamiprid (ACE) and imidacloprid (IMI), two commonly used pesticides, from pistachio samples before their determination by HPLC–UV. The pesticides were firstly extracted from pistachio samples and cleaned-up by QuEChERS, and then their supernatant was used as a dispersant in following DLLME in order to further purification and preconcentration. The extraction solvent used in DLLME was based on deep eutectic solvents (DESs). Preparation of hydrophobic DES was done by mixing amyl alcohol as hydrogen bond donor and trioctylmethylammonium chloride (TOMAC) as hydrogen bond acceptor. Different parameters that affect the efficiency of the two steps were evaluated and optimized. Under optimal conditions, the limit of detections was 1.5 and 3.0 μg kg−1 for ACE and IMI and the limit of quantification was 1.5 and 4.5 μg kg−1 for ACE and IMI, respectively. Calibration curves were linear in the range 5.0–500 μg kg−1 with correlation coefficients higher than 0.99. Preconcentration factor for ACE and IMI was 16 and 13, respectively. The intraday and interday precisions at concentration levels of 10 and 100 μg kg−1 were less than 7.0%. Finally, applicability of the suggested method was investigated through analysis of the analytes in some pistachio samples, and the obtained relative recoveries (95.6–99.4%) were acceptable. The good sensitivity and suitable purification in the analysis of the pistachio samples, as a complex food matrix, are obtained using the proposed method by combining the advantages of QuEChERS and DLLME.