Determination of three kinds of chloroacetanilide herbicides in radix pseudostellariae by accelerated solvent extraction and gas chromatography-mass spectrometry

A gas chromatographic-mass spectrometry (CC-MS) method for the determination of herbicides acetochlor, butachlor and S-metolachlor in Radix Pseudostellariae (Taizishen in Chinese), a widely used Chinese medicinal herb, was developed. The herbicides in the plant. samples were extracted by accelerated solvent extraction (ASE). ASE conditions, including extraction solvent, temperature, clean-up reagent, flush volume, static time and static cycle were optimized. The extract was concentrated and then analyzed by GC-MS under select ion monitoring (SIM) mode. The herbicide residues were quantified by internal standard method. The detection limits and relative standard deviations for acetochlor, S-metolachlor and butachlor were 0.16 ng/g, 0.05 ng/g, 0.18 ng/g, and 2.6%, 3.1%, 3.9%, respectively. The average recoveries ranged from 80.2% to 104.1%. The three target herbicides were not detected in all the samples we analyzed. The method is easy to operation, and with good precision, it is therefore well suited for the routine analysis of herbicides. in herb samples such as Radix Pseudostellariae.