Preparation of a new three-component deep eutectic solvent and its use as an extraction solvent in dispersive liquid-liquid microextraction of pesticides in green tea and herbal distillates.

Abstract

BACKGROUND\nA new growing interest solvent named deep eutectic solvent has been prepared and used as an extraction solvent in the dispersive liquid-liquid microextraction method. In order to prepare the solvent, dichloroacetic acid, L-menthol, and n-butanol at a molar ratio of 4: 1: 1 are mixed and after heating the deep eutectic solvent is formed. Then a dispersive liquid-liquid microextraction method using the prepared solvent is done for the extraction and preconcentration of some pesticides from an aqueous sample. In order to perform the method, the deep eutectic solvent is mixed with methanol and rapidly injected by a syringe into the aqueous sample containing the analytes. After centrifuging an aliquot of the sedimented phase is injected into the gas chromatograph. The influence of several variables on the extraction efficiency was investigated and optimized.\n\n\nRESULTS\nExtraction recoveries and enrichment factors were obtained in the ranges of 53-86% and 1760-2853, respectively. Intra- (n\xa0=\xa06) and inter-day (n\xa0=\xa05) precisions of the method were satisfactory with relative standard deviations ≤7% obtained at two concentrations of 10 and 50\u2009μg\u2009L-1 of each analyte. Moreover, detection and quantification limits for the target analytes were obtained in the ranges of 0.11-0.23 and 0.38-0.74\u2009μg\u2009L-1 , respectively.\n\n\nCONCLUSION\nDifferent samples including green tea, rose water, lemon balm, mint, and pussy willow distillates were analyzed successfully by the developed method and chlorpyrifos was found in rose water at a concentration of 17\u2009±\u20091\u2009μg\u2009L-1 (n\xa0=\xa03). This article is protected by copyright. All rights reserved.