FLOW-INJECTION ELECTROCHEMICAL HYDRIDE GENERATION TECHNIQUE FOR ATOMIC-ABSORPTION SPECTROMETRY

A flow injection-electrochemical hydride generation technique for atomic absorption spectrometry has been developed in order to avoid the use of sodium tetrahydroborate, which is capable of introducing contamination. A specially designed thin-layer electrolytic flow cell for hydride generation was used in a normal flow injection system coupled to an electrically heated T-tube atomizer for the atomic absorption measurements. About 200-mu-l of sample were injected into the electrolyte carrier stream flowing to the electrolytic cell, where hydride-forming elements were reduced to gaseous hydrides. The effects of various factors, e.g., electrode material, electrolyte, current density and carrier stream flow rate, on rate of formation of the hydride and interferences have been studied. The technique has been applied to the determination of As, Se and Sb in various samples. The detection limits for these elements in aqueous solutions were 0.45, 0.62 and 0.92 ng ml-1, respectively, with precisions of 1.2-1.8%.