Speciation of aluminum in soil extracts using cation and anion exchangers followed by a flow-injection system with fluorescence detection using lumogallion.

Flow-injection analysis (FIA) with fluorescence detection of aluminum using lumogallion was applied to the chemical speciation of aluminum in soil extracts after the separation of aluminum species with ionic exchangers. Aluminum complexes with organic substances (anion species) can be specified from other species by using a strongly acidic cation exchanger in the pH range of 3 to 5. Furthermore, aluminum can be separated into three categories, namely, (i) the Al3+ and Al-OH complex, (ii) aluminum organic complexes (cation species), and (iii) its anion species by using a strongly acidic and a weakly acidic cation exchanger at around pH 5. A considerable percentage of water-soluble aluminum in soils was found to be complexes with humic substances.