Determination of total inorganic arsenic in water samples by cadmium ion assisted photochemical vapor generation-atomic fluorescence spectrometry

A novel approach based on cadmium ions assisted photochemical vapor generation (PVG) combined with atomic fluorescence spectrometry (AFS) was proposed for sensitive and accurate detection of total inorganic arsenic. In this work, the prereduction step of As(V) to As(III) was avoided. An approximate 10-fold improvement in sensitivity was achieved for both As(III) and As(V) with the existence of 20 mg L-1 Cd2+ in the 30% (v/v) acetic acid solution for 60 s UV irradiation. Under the optimal experimental conditions, detection limits of 0.05 mu g L-1 were obtained for As(III) and As(V). The relative standard deviations (RSD) of the 20 mu L-1 As(III)/As(V) standard solution from 11 times measurements were both within 2%. The accuracy of the proposed approach was verified by analyzing of several surface water samples using standard addition method, Yangtze river waters and Funan river waters, with recoveries from 94% to 105%, which were in good agreement with the results from ICPMS determination.