Residues and dissipation dynamics of butralin in ginseng by high performance liquid chromatography-tandem mass spectrometry

A high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of the residues of butralin in ginseng was established, and the dissipation dynamics and terminal residues of butralin in ginseng were investigated. The samples were extracted by acetonitrile, cleaned-up by NH₂ solid phase extraction (SPE) cartridges, detected by liquid chromatography-tandem mass spectrometry, and quantified with external standard method. The results showed that in the range of 0.002-0.5 mg/L, there was a good linear relationship between the mass concentration of butralin and the corresponding peak area. The recoveries of butralin were 93%-108% and the relative standard deviations were 0.60%-6.2% at spiking levels of 0.01, 0.05 and 0.5 mg/kg for fresh ginseng and dried ginseng and at spiking levels of 0.01, 0.05, 0.5 and 10 mg/kg for ginseng plant and soil. The half-lives of butralin in ginseng plant and soil were 10.81-18.91 days, and the terminal residues of butralin in fresh ginseng, dried ginseng, ginseng plant, and ginseng soil were <LOQ-0.010 mg/kg, <LOQ-0.024 mg/kg, 0.011-0.19 mg/kg, and 0.16-0.41 mg/kg, respectively. It is suggested that the maximum residue limit (MRL) of butralin in ginseng could be tentatively set at 0.05 mg/kg, and the harvested ginseng was safe for consumption after the 48% butralin EC was sprayed on the soil surface once at dosage of 3750 g/hm² (active ingredient of 1800 g/hm²) before the emergence of ginseng seedling.