Determination of Triazole Fungicide Residues in Fruits by QuEChERS Combined with Ionic Liquid-Based Dispersive Liquid-Liquid Microextraction: Optimization Using Response Surface Methodology

Abstract

A rapid, efficient, and environmentally friendly method using quick, easy, cheap, effective, rugged, and safe (QuEChERS) combined with ionic liquid-based dispersive liquid-liquid microextraction (QuEChERS-IL-DLLME) prior to high-performance liquid chromatography coupled with photodiode array detection (HPLC-PDA) has been developed for the determination of six triazole fungicides (triazolone, triadimenol, epoxiconazole, flusilazole, tebuconazole, and diniconazole) in various fruits (pear, apple, and grapefruit). Several parameters affecting the extraction efficiency in IL-DLLME, such as type and volume of ionic liquid and acetonitrile volumes and extraction time, were investigated by single factor experiments. Then, the extractant volume, dispersant volume, and extraction time were optimized using response surface methodology (RSM). The optimal values were determined to be within an extractant volume of 63.7 μL, a dispersant volume of 0.43 mL, and an extraction time of 1.7 min, respectively. Under the optimum conditions, an excellent linearity with determination coefficient higher than 0.997 was obtained. The average recoveries in three concentration levels (0.2, 0.5, and 1 mg kg−1) ranged from 63.8 to 119.1 %, respectively, and the relative standard deviations (RSDs) from 1.1 to 12.6 %. The limits of detection (LODs) (S/N = 3) and limits of quantification (LOQs) (S/N = 10) for the six triazole fungicides ranged from 3.4 to 26.8 μg kg−1 and 9.8 to 50.3 μg kg−1, respectively. The proposed method was successfully applied for the determination of trace amounts of triazole fungicides in various fruits including pear, apple, and grapefruit.