FORMATION AND INTERPRETATION OF DOUBLE PEAKS IN FLOW-INJECTION HYDRIDE GENERATION ATOMIC-ABSORPTION SPECTROMETRY

Under conditions which are non-optimum, such as low quartz tube atomizer temperatures, insufficient oxygen supply and excessively high analyte element concentrations, double peaks and a shift in time of the second peak may be observed in flow injection hydride generation atomic absorption spectrometry. These phenomena could be explained satisfactorily by a hydrogen radical depletion which results in the formation of mono- and di-hydrides of antimony and arsenic instead of atoms. These mono- and di-hydrides are thermally decomposed to the element and retained in the heated quartz tube and may be re-volatilized and atomized by reaction with hydrogen radicals. The phenomena described in this work strongly support the hydrogen radical mechanism of atomization of arsine and stibine in an externally heated quartz tube atomizer.