Electrochemical Hydride Generation:A Novel Sample Introduction Method for the Non-dispersive Atomic Fluorescence Spectrometry

Production of volatile covalent hydrides of environmentally important elements (As、Se、Bi、Ge、Sn、Sb and Pb) by reaction with sodium (potassium) tetrahydroborate (NaBH₄) in acidic media for determination by atomic absorption has been widely used in routine analysis. However, this technique has several disadvantages. NaBH₄ is a potential source of contamination, its aqueous solution is unstable. As an alternative to chemical hydride generation, hydride generation by electrochemical reduction (EcHG) has been reported in recent years by many authors^1-3]. Compared with NaBH₄ hydride generation system, the EcHG with subsequent detection by atomic absorption spectrometry offers the high sensitivity, low detection limits, and the absence of interference from the transition metals. However, the hydrogen produced by EcHG reduced greatly, this led to the interference caused by hydride forming elements was serious due to the lack of free hydrogen (H·) radical in the quartz tube during the atomization. EcHG coupled with atomic fluorescence spectrometry system uses Ar-H2 mini-flame as an atomizer, in which the gaseous phase interference can be expected eliminated. In addition, non-dispersive atomic fluorescence spectrometry (NDAFS) system with a quite single structure, is a very sensitive and feasible method for the measurement of elements that form volatile hydrides. By combining with electrochemical hydride generation as a sample introduction technique, it is possible to develop a potential interface for chromatography or capillary electrophoresis in speciation analysis.