Modified QuEChERS Method for the Determination of Multiclass Pesticide Residues in Fruit Samples Utilizing High-Performance Liquid Chromatography

A modified quick, easy, cheap, effective, rugged, and safe method (QuEChERS) followed by high-performance liquid chromatography (HPLC) with variable wavelength detector (VWD) has been developed for the quantitative determination of six multiclass pesticide residues including atrazine, ametryn, and terbutryn among herbicides; methidathion and carbaryl among insecticides; and chlorothalonil which is a fungicide. The QuEChERS extraction method developed was aimed to extract and preconcentrate the target analytes from selected fruits such as tomato, watermelon, and papaya samples. Various experimental parameters affecting the extraction efficiency of the method including the use of dispersive solid-phase extraction (d-SPE) cleanup, types and amount of salts, sample size, and composition as well as volume of the extraction solvent, acetonitrile, were optimized. Under the optimum experimental conditions, matrix-matched calibration curves were constructed using the tomato sample as the representative matrix and good linearity, over wide concentration ranges, was obtained with a coefficient of determination (r (2)) of 0.990 or better. The limits of detection (LOD) and quantification (LOQ) of the proposed method were in the ranges of 1.7-3.3 and 5.8-11.1 mu g kg(-1), lower than the maximum residue limits set by the European Union for the raw fruits, such as tomato, watermelon, and papaya. The relative standard deviations (RSDs) of the intra- and inter-day precision studies were varied over the range of 0.2-11.7 %. The proposed method was successfully applied to different fruit samples, and satisfactory recoveries, ranging from 78 to 118 %, were obtained.