Abstract: The method for determination of halauxifen-methyl in barley was established by gas chromatography. The samples were extracted by acetone and then separated by centrifugation. The acetone solution was died by N₂, dissolved by n-hexane with certain volume and then determined by gas chromatography with electron capture detector. The component was qualitated by retention time and quantitated by peak area using external standard method. Halauxifen-methyl had a good linearity between 0.02~0.50 mg/L,r=0.999 1, with detection limit of 0.004 mg/kg. Test for recovery was made by standard addition method using blank samples. The values of recovery ranged from 86.4%~92.1%. Values of RSD（n=6） found were in the range of 9.1%~12.3%. The method was simple with high sensitivity and wide linear range, which was valuable for the determination of halauxifen-methyl in barley.

Key words: halauxifen-methyl, gas chromatography, barley