Flow-injection column preconcentration directly coupled with electrothermal atomization atomic absorption spectrometry for the determination of aluminium. Comparison of column packing materials

Abstract

A method has been developed for the determination of endogenous levels of aluminium (>1 μ l −1) in water samples using an automated on-line preconcentration system with flow injection coupled directly to an electrothermal atomic absorption spectrometer. Two preconcentration materials, 8-quinolinol immobilized on controlled-pore glass (8-Q-CPG) and Amberlite XAD-2, poly(styrene/divinyl benzene) copolymer (XAD-2) were investigated and compared. Both systems were found to be suitable for preconcentration. However, the sampling flow-rate for the 8-Q-CPG system was found to be much lower than that of the XAD-2 system, relative to the same magnitude of preconcentration. The chelating kinetics of the 8-Q-CPG system were less favourable than the adsorption kinetics of the XAD-2 system. The detection limits (3SD) varied from 15 to 40 ng l −1, depending on the preconcentration time, with RSDs of the order of 4% for a 1 μg l −1 concentration of aluminium. The optimum concentration range for the application of the method developed was 50 ng l −1 to 3 μg l −1. Recoveries for drinking water were in the range 100–115% for the 8-Q-CPG system and 90–100% for the XAD-2 system. The method developed was applied with varying results to the analysis of potable, fresh, river and sea water samples.