Dispersive liquid–liquid microextraction method for the extraction of some acidic pesticides (Haloxyfop, fenoxaprop, fluazifop) in edible oils following with HPLC

Abstract

This study consists of two part. In the first part, a sample pretreatment based on the combination of vortex assisted liquid–liquid extraction and dispersive liquid–liquid microextraction has been proposed for the isolation and preconcentration of three acidic herbicides including fenoxaprop, fluazifop, and haloxyfop from edible oil samples. For this purpose, firstly, the analytes were extracted into sodium hydroxide solution (by deprotonating the analytes) which was used as a dispersive solvent in the following microextraction procedure. The obtained aqueous phase was mixed with acetic acid as a pH adjustment agent and co– disperser solvent. After the addition of dichloromethane (extraction solvent) to the above solution, it was quickly dispersed into deionized water. The validation parameters indicated that the limits of detection and quantification of the proposed method were in the ranges of 0.3–1.8 and 1.0–6.0 ng mL–1, respectively. Relative standard deviations of the method were obtained in the range of 4.8–6.2% and 5.2–9.1% for intra– (n=6) and inter–day (n=5) precisions, respectively. High extraction recoveries and enrichment factors ranged from 74 to 91%, and 185 to 227 were the other advantages of the method. These merits showed that the proposed method is efficient and sensitive for the determination of the studied analytes in the edible oil samples. And in the second part of study, A simple, efficient, and sensitive microextraction procedure named ion-paring deep eutectic solvent based dispersive liquid-liquid microextraction was developed and used for the determination of three acidic herbicides including fenoxaprop, fluazifop and haloxyfop from edible oil samples. For this purpose, firstly, a three component deep eutectic solvent composed of phosphocholine chloride, dichloroacetic acid, and decanoic acid was prepared under mild condition and it was used in microextraction process. Firstly, the analytes were extracted into sodium hydroxide solution by deprotonation of the analytes. Afterward, the deprotonation pesticides were extracted into phosphocholine chloride: dichloroacetic acid: decanoic acid with the aid of tri-butyl amine (ion-pair agent) in the presence of acetic acid (as a pH adjustment agent and dispersive solvent)The validation parameters indicated that the method has low limits of detection and quantification in the range 0.09 to 0.71 and 0.3 to 2.3 ng mL–1, respectively. The relative standard deviations of the method were obtained in the range of 4.8–6.9% and 7.9–9.0% for intra– (n=6) and inter–day (n=5) precisions, respectively. High enrichment factors ranging from 566 to 626 and extraction recoveries ranging from 85 to 94% were the other advantages of the method. These merits showed that the method is an efficient, inexpensive and successful procedure in the determination of the analytes. The method was successfully performed in the determination of 35 edible oil samples and haloxyfop was found in three corn oil samples.