A method was tested for the determination of aluminum by graphite furnance atomic absorption spectrometry using hydrofluoric acid and cesium fluoride as matrix modifiers. Alunimum trifluoride is stable to 1291°C, after which it sublimes to form AlF3 gas. The subsequent gas-phase atomization of AlF3 occurs rapidly, and produces clean, sharp absorption peaks. This method has a detection limit of 7 pg Al at a confidence interval of 95%. The method is fairly insensitive to interferences, with the exception of strongly complexing organic acids. The addition of CuF2 to the matrix appears to eliminate interference from organic acids, but was found to produce a high background absorbance and to shorten the life of the graphite tube.
Bibliographical noteFunding Information:
The authors thank Dr. Ken Jackson for his help in obtaining the absorbance/temperature data. This research was supported by Research Project 4154:P roperties of native and homogeneouslys ynthesized non-crystalline soil materials, University of California Experiment Station. This paper is a joint contribution of the University of California Agricultural Experiment Station, and the Minnesota Agricultural Experiment Station, University of Minnesota.