Simultaneous determination of nine dinitroaniline herbicides in environmental samples using a validated vortex-assisted dispersive liquid-liquid microextraction procedure coupled with GC-MS/MS

摘要

A sensitive, rapid, cheap and ecologically safe analytical method has been developed for simultaneous quantification of nine dinitroaniline herbicides (ethalfluralin, trifluralin, benfluralin, profluralin, fluchloralin, isopropalin, pendimethalin, nitralin, prodiamine) in environmental samples, namely surface water, soil and food (tomato) matrices. Vortex-assisted dispersive liquid-liquid microextraction (VA-DLLME) sample preparation and gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) enabled simultaneous quantification of the nine dinitroaniline herbicides in as little as 20 min. The effects of different variables on the DLLME procedure were evaluated, including the type and volume of disperser solvent, the volume of chloroform as the extractant solvent, and extraction time. An optimal analyte protectant mixture (0.5, 1, and 1 mg/mL D-sorbitol, shikimic acid, and δ-gluconolactone, respectively) was identified and employed to improve the detection sensitivity for the tested analytes; this mixture was added to the standards in solvent and used instead of matrix-matched calibration curves during quantification. The selectivity, linearity, precision and accuracy of the proposed methodology were validated: the correlation coefficients were > 0.99 and the limits of detection ranged from 0.3 to 3.3 μg/L for the tested analytes. The limits of quantification (LOQ) ranged from 0.4 to 2 μg/kg in surface water and 2 to 10 μg/kg in soil and tomato samples. Percentage recovery at the LOQ ranged from 64.1 to 87.9%, with inter-day repeatability of ≤ 15.1%. The proposed method was also used to monitor the target analytes in real samples.