GC Determination of Residual Amount of Ethephon in Grapes with Headspace

The grape sample was weighed and put into the headspace bottle with sodium chloride added in advance. The saturated potassium hydroxide solution was added then. GC was applied to the determination of residual amount of ethephon in the above mixture with headspace. The temperature and time of headspace were set at 75℃ and 90 min. The analyte was separated on HP-5 chromatographic column (30 m×0.32 mm, 0.25 μm) and detected by hydrogen flame ionization detector. Linear relationship between values of peak area and mass concentration of ethephon was kept in the range of 0.500-50.0 mg·L^-1, with detection limit (3S/N) of 0.010 0 mg·kg^-1. The proposed method was applied to the analysis of the grape sample, giving values of recovery found by standard addition method and RSDs (n=6) of determined values in the ranges of 99.9%-104% and 1.9%-3.5% respectively.