Determination of Three Kinds of Chloroacetanilide Herbicides in Radix Pseudostellariae by Accelerated Solvent Extraction and Gas Chromatography-Mass Spectrometry

A gas chromatography-mass spectrometry (GC-MS) method for the determination of herbicides, acetochlor, butachlor and S-metolachlor in Radix pseudostellariae (Taizishen in Chinese), a widely used Chinese medicinal herb, has been developed. The herbicides in the plant samples were extracted by the accelerated solvent extraction (ASE) method. 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 the select ion monitoring (SIM) mode. The herbicide residues were quantified by the internal standard method. The detection limits and relative standard deviations for acetochlor, S-metolachlor and butachlor were 0.16 ng g−1, 0.05 ng g−1, 0.18 ng g−1, 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 operate with good precision. It is, therefore, well suited for the routine analysis of herbicides in herb samples such as Radix pseudostellariae.