Dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry for the determination of pesticide residues in nutraceutical drops.

An economical and rapid method has been developed using dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry to extract and determine forty pesticides in nutraceutical drops containing alcohol. Parameters affecting the DLLME performance, such as solvent selection and volume of extractive and dispersive solvent, salt effect, pH, mixing type and extraction time, were studied. Tetrachloroethane was the selected extraction solvent. Ethanol contained in the sample was enriched by methanol to serve as dispersive solvent. The method was fully validated under the optimized extraction parameters. The recoveries of pesticides were between 70 and 120% with relative standard deviations less than 20%. The limits of detection ranged from 0.001 to 0.910 μg/L and the limits of quantification ranged from 0.004 to 3.003 μg/L. The optimized method was employed for determination of pesticide residues in real samples of nutraceutical drops and herbal alcoholic beverages.