Interferences from hydride-forming elements on selenium in hydride-generation atomic absorption spectrometry with a heated quartz tube atomizer

Abstract

The interference from antimony(III), arsenic(III) and (V), bismuth(III), tin(IV) and tellurium(IV) on the determination of selenium(IV) in hydride-generation atomic absorption spectrometry (HG—AAS) was investigated systematically. Two commercially available units, a batch and a flow injection system, were compared. A dual system in which the interferent hydride was generated continuously, whereas the selenium hydride was generated intermittently and mixed with the interferent only shortly before the quartz tube atomizer, was used to further elucidate interference mechanisms. In the batch system, radical deficiency was found to be the main reason for the low tolerance of other hydride-forming elements. In the flow injection system, radical deficiency was not a major problem. The prevailing mechanism was an analyte atom decay interference due to surface alteration caused by deposition of the interferent in the quartz tube atomizer. Bismuth caused, in addition, a transport efficiency interference. Analyte decay interferences could be reduced by increasing the carrier gas flow. In the flow injection system, under optimized conditions, tolerance limits were 1–2 orders of magnitude higher than in the batch system. In most cases the big differences in the tolerance limits for hydride-forming elements reported in the literature could be interpreted on the basis of the conditions or the instrumentation used by these authors.