Matrix removal by thermal fluorination in the graphite furnace atomic absorption analysis of high purity aluminum

A halogen assisted thermal purification method was developed with the use o f Ar + 1% (v/v) CHF3 internal furnace gas and applied specifically to the d etermination of iron impurities in high-purity aluminum. The samples were a pplied in the form of hydrochloric acid solution, and the alumina formed by hydrolysis from the chloride salt was reacted with the halocarbon in the p yrolysis step to attain a complete volatilization of the matrix without los s of the analyte (Fe). As a result, no interfering background in the 200-34 0-nm spectral range was observed that was otherwise very intensive without halogenation. The deuterium lamp background correction method was appropria te up to a sample amount of 400 mu g , resulting in a characteristic concen tration of 3.7 ng g(-1) (ppb) Fe in the solid aluminum sample. (C) 2000 Els evier Science B.V. All rights reserved.