Rapid Multi-Residue Analysis of Herbicides with Endocrine-Disrupting Properties in Environmental Water Samples Using Ultrasound-Assisted Dispersive Liquid–Liquid Microextraction and Gas Chromatography–Mass Spectrometry

Abstract

A highly efficient ultrasonic-assisted dispersive liquid–liquid microextraction (UA-DLLME) procedure coupled with gas chromatography–mass spectrometry was developed for simultaneous analysis of multiclass herbicides with endocrine-disrupting properties in environmental water samples. The parameters affecting the method’s extraction efficiency, such as the types and volumes of the extractant and dispersive solvents, sample pH, and salt concentration, were systematically optimized by response surface methodology based on central composite design to achieve excellent recoveries for multiclass herbicides. The final UA-DLLME protocol involved 115.6 µL of chloroform (extractant), 861.5 µL of ethanol (dispersive solvent), 5.0 mL of water samples, pH 10.0, and 4.3% NaCl solution. The performance of the developed UA-DLLME was compared with that of conventional solid-phase extraction (SPE). Under optimal extraction conditions, UA-DLLME exhibited a higher enrichment factor and greater sensitivity than SPE, with limits of detection and limits of quantification of 0.004–0.024 and 0.013–0.079 µg L−1, respectively, for seawater samples. The accuracy and precision of UA-DLLME were satisfactory for seawater samples spiked at three levels (0.2, 2.5, and 5.0 µg L−1). Average recoveries ranging from 82.3 to 101.8% were achieved, with relative standard deviations lower than 12.8%. The proposed analytical method was successfully applied to the simultaneous determination and quantification of 17 herbicides in environmental river and seawater samples.