Improvements of hydride generation for the speciation of arsenic in natural freshwater samples by HPLC-HG-AFS

A new gas-liquid separator was used to improve the hydride generation step of a hyphenated HPLC-HG-AFS system applied to arsenic speciation studies. O ptimisation of the hydride generation atomic fluorescence detection with th is new device produced by SpectraFrance led to a significant improvement in performance. Absolute detection limits were as low as 5-7 pg As for the fo ur arsenic species usually encountered in water samples: As(III), As(V), mo nomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA). Using a 100 mu l injection volume the concentration detection limits were in the range 0.0 5-0.07 ng ml(-1). The optimised procedure was applied to determine arsenic speciation in a wide range of natural fresh water samples.