Alkali metal fluoride matrix modifiers for the determination of trace levels of silicon by graphite furnace atomic absorption spectrometry

Edward A. Nater, Richard G. Burau

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Abstract

A method is described for the determination of silicon by graphite-furnace atomic absorption spectrometry with alkali metal fluorides as matrix modifiers. Alkali metal fluorides react with silicon to produce metal hexafluorosilicates, which are stable at temperatures as high as 1120- 1300°C, depending on the particular metal used. At higher temperatures, alkali metal hexafluorosilicates decompose into the metal fluoride and silicon tetrafluoride. The subsequent gas-phase atomization of silicon tetrafluoride occurs rapidly, and produces clean, sharp absorption peaks. When used in conjunction with a zirconium-treated graphite tube, this method has a sensitivity of 50 pg Si at a confidence interval of 95%. There is no evidence of silicon carbide formation in the graphite tube, and very little evidence of any deterioration of the zirconium-treated surface, as demonstrated by the fact that more than 200 samples can be processed on a single graphite tube without a decrease in sensitivity or change in the baseline.

Original languageEnglish (US)
Pages (from-to)83-92
Number of pages10
JournalAnalytica Chimica Acta
Volume220
Issue numberC
DOIs
StatePublished - 1989

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