Determination of aluminium in soil extracts by carbon arc emission spectrometry after coprecipitation with iron using 8-hydroxyquinoline

Abstract

Coprecipitation with iron, followed by analysis of the ignited precipitate in a cathode layer carbon arc, is shown to be effective for determining aluminium in soil extracts containing from 0.02 to 20 µg ml^–1 of aluminium. When 0.5 M acetic acid or 1 M ammonium acetate solution (pH 7) is used as soil extractant, the untreated extract can be analysed directly as the precipitation with 8-hydroxyquinoline is carried out in acetate-buffered solution at pH 5–5.2. A relative standard deviation of about 3% was obtained using the Al 394.4-nm and Fe 311.6-nm line pair. A minimum of about 5 µg of aluminium in up to 200 ml of extract was needed for the analysis, but this was mainly determined by the laboratory environment and could be reduced.