Differentiation of Al3+ and Al species in environmental samples by isotachophoresis

An isotachophoretic method for the determination of free [Al(H2O)6]3+ ions in different aluminium salt solutions was developed. The electrolyte system consists of 0.01 M sodium acetate (leading system) and 0.01 M tris(hydroxymethyl)amino-methane (terminating system). Separation was effected with a precapillary tube (diameter 0.05 cm) followed by a main capillary tube of length 20 cm and of smaller cross-section. The detection limit for [Al(H2O)6]3+ ions was 0.05 mg/l. The method was applied to the determination of free Al3+ ions ([Al(H2O)6]3+) in soil leachates and aqueous soil extracts.