Determination of four herbicide residues in fruit juice and vegetable samples using a new version of dispersive liquid–liquid microextraction followed by gas chromatography–flame ionization detection

In this study, a new sample preparation method based on dispersive liquid–liquid microextraction has been developed for the extraction and preconcentration of aryloxyphenoxy–propionate herbicides from aqueous samples prior to their analysis by gas chromatography–flame ionization detection. In this method, two parallel glass tubes with different diameters and lengths are connected with a teflon stopcock and used as an extraction device. A mixture of disperser (acetone) and extraction (1–octanol) solvents is transferred into one side (narrow tube) of the extraction device and an aqueous phase containing the analytes is filled into the other side (wide tube) of it. Then the stopcock is slowly opened and the mixture of disperser and extraction solvents mixes with the aqueous phase. By this action, the extraction solvent is dispersed continuously as fine droplets into the aqueous sample and the target analytes are extracted into the fine droplets of the extraction solvent. The fine droplets move up through the aqueous phase due to its low density compared to aqueous phase and collect on the surface of the aqueous phase as an organic layer. Finally an aliquot of the organic phase is removed and injected into the separation system for analysis. Under the optimum extraction conditions, the extraction recoveries and enrichment factors ranged from 49 to 74% and 1633 to 2466, respectively. The results indicated that the developed method had many merits such as excellent extraction performance, higher EFs, more sensitive, and better repeatability. Finally the proposed method was successfully applied to determine the target herbicides in fruit juice and vegetable samples and haloxyfop–R–methyl was determined in onion sample.

کلیدواژه ها:

dispersive liquid–liquid microextraction ، Gas chromatography ، Aryloxyphenoxy–propionate herbicides