Sequential injection analysis system for total inorganic arsenic determination by hydride generation-atomic fluorescence spectrometry

A sequential injection analysis system is proposed for total inorganic arsenic determination by hydride generation-atomic fluorescence spectrometry. The sample, a reducing sodium tetrahydroborate solution and a blank solution containing HCl, ascorbic acid and potassium iodide are sequentially aspirated and then dispensed into a gas-liquid separation cell. An Ar flow sweeps the arsine into the flame of an atomic fluorescence spectrometer. An auxiliary H-2 flow was necessary to support the flame. Linear calibration graphs were obtained for arsenic concentrations between 2.5 and 50 mu g l(-1), the detection limit (3 sigma(b)/S) being 0.67 mu g l(-1). The relative standard deviation of the method was 1.8% (n=9) when 0.5 ml of a 20 mu g l(-1) As standard solution was aspirated. The sample throughput was 33 samples per hour. The proposed method has been validated by means of reference materials and the results obtained were in good agreement with the certified values. (C) 2000 Elsevier Science B.V. All rights reserved.