The QuEChERS analytical method combined with low density solvent based dispersive liquid–liquid microextraction for quantitative extraction of multiclass pesticide residues in cereals
In this study, a combination QuEChERS and low density solvent based DLLME was developed for extraction and preconcentration of five multiclass pesticide residues including atrazine, ametryn, terbutryn, carbaryl and chlorothalonil, from selected cereals: Teff, barley and maize samples. Liquid chromatography with variable wavelength detector (VWD) was used for quantitative determination of the pesticides. Various experimental parameters affecting the extraction and the preconcentration efficiencies were optimized. Calibration curves constructed using Teff samples were linear over wide ranges, 7.1-200 μg kg-1 with R2 ≥ 0.990. LODs of the method were ≤ 8.9 μg kg-1, below the MRLs of EU for maize and barley. The RSDs were in the range of 2.3–9.5%. The method has also been applied to different cereal samples and satisfactory average recoveries ranging 69.0–117% were obtained for the spiked cereal samples at two concentration levels. Therefore, the developed method can be successfully utilized as a simple alternative for the analysis of multiclass pesticide residues in cereals and other related samples.
KEY WORDS: QuEChERS method, Low density solvent based DLLME, Multiclass pesticide residues, Cereal samples, HPLC-VWD, Quantitative extraction
Bull. Chem. Soc. Ethiop. 2017, 31(1), 1-15.