Aspects of chloride interference in zinc determination by atomic-absorption spectroscopy with electrothermal atomization.
During the determination of zinc in a polluted stream by atomic-absorption with electrothermal atomization, chloride was found to exercise a large negative interference (40%) when a carbon-filament atomizer was used, but not when a graphite-furnace atomizer was used. The effect on the filament method was confirmed and shown to be due to the formation of zinc chloride, and further complicated by interaction of this with iron. This interference could be overcome by the use of aqueous ammonia solution or silver nitrate added as matrix modifier. The absence of interference in the graphite-furnace method is attributed to the liberation of hydrogen and removal of chloride as hydrogen chloride. It is further suggested that these observations offer a basis for the exploration of apparently contradictory reports in the literature.
Ebdon
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Department of Chemistry, Sheffield City Polytechnic, Pond Street, Sheffield, England.
Ellis
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Ward
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