A simple method was developed for speciation and spectrophotometric determination of inorganic As(III) and As(V) using an electrochemical hydride generation technique. For speciation of As(III) and As(V), a graphite rod was used as cathode to reduce As(III) to AsH
3, the rod was then replaced with a tin-lead alloy wire for reducing As(V) to AsH
3. The spectrophotometric determination was based on the reaction of AsH
3 with silver diethyldithiocarbamate to give an absorbing complex at 510 nm. Under the optimized conditions, the calibration curves were linear over the ranges of 0.1 − 5 μg ml
−1 for As(III) and 0.5 − 4.0 μg ml
−1 for As(V). The concentration detection limits of 0.02 and 0.06 μg ml
−1 were achieved for As(III) and As(V), respectively. The relative standard deviations for five replicate speciation and determination of 3.0 μg ml
−1 As(III) and As(V) were 0.8 and 7.2%, respectively. The accuracy and recovery of the method were evaluated by analyzing tap water spiked with As(III) and As(V).
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