Solid phase extraction-spectrophotometric determination of dissolved aluminum in soil extracts and ground waters.

An on-line solid-phase extraction (SPE) technique, linked to spectrophotometry, has been developed to overcome the problem of high matrix concentration, which is thought to interfere with the determination of low levels of aluminum (Al) in environmental samples. Tiron modified resin was prepared and used as a SPE absorbent, which can quantitatively adsorb Al(III) at pH 4-6 with an adsorption capacity of 5.6 mg g(-1) resin. The main advantages of this novel method are: (1) a much higher sensitivity has been obtained by SPE technology; and (2) a large amount of Na(+), K(+), Ca(2+) and Mg(2+) can be removed and the interference of Fe(III), Mn(II) and F(-) can be efficiently eliminated by eluting with 0.25 mol l(-1) NaOH. It is a highly selective and sensitive method for simple and quick determination of dissolved Al in soil extracts and ground waters, particularly suitable for the analysis of complex environmental samples.