Chinese Journal of Chromatography

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Determination of 29 acidic herbicide residues in tea by gas chromatography-mass spectrometry

YAN Hongfei, HUANG Zhiqiang*, ZHANG Ying, LI Yongjun, WANG Meiling   

  1. Technology Center, Hunan Entry-Exit Inspection and Quarantine Bureau, Changsha 410004, China
  • Received:2008-09-04 Revised:2008-11-04 Online:2009-05-30 Published:1982-09-25
  • Contact: HUANG Zhiqiang

Abstract: A method was developed for the determination of 29 herbicide residues in tea. The target analytes were extracted with acetonitrile. The extract was cleaned up with an ENVI-Carb solid phase extraction column and derivatized with trimethylsilydiazmethan, then cleaned up through a Florisil solid phase extraction column. The derivatives were determined by gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM) mode. The separation and quantification were achieved using an HP-5MS silica capillary column (30 m×0.25 mm×0.25 μm) with a column temperature gradient from 50 ℃ (held for 1 min) to 160 ℃ at a rate of 4 ℃/min, held for 3 min and then increased to 300 ℃ for 5 min at a rate of 10 ℃/min. The average recoveries of these herbicides at three spiked levels (0.01, 0.05 and 0.1 mg/kg) ranged from 57.1% to 120.4% with the relative standard deviations (RSDs) ranged from 4.3% to 20.9%. The detection limits were from 0.002 mg/kg to 0.005 mg/kg. The method is easy, fast, and more sensitive. It also indicated that this method can meet the requirements for simultaneous determination of 29 herbicides in tea.

Key words: derivatization, herbicides, solid phase extraction (SPE), tea , gas chromatography-mass spectrometry (GC-MS)