The homemade on-line ultraviolet( UV) digestion device was coupled with atomic fluorescence spectrometer. The effect of the on-line UV digestion efficiency on the measurements of arsenobetaine( As B) and arsenic choline( As C) was investigated. Effects of the UV digestion power,the length of UV digestion pipeline,the concentration of the assisted digestion agent and the p H value on the UV digestion efficiency were investigated in detail. Under the optimal conditions,linear ranges of both As B and As C were...