Improvements in the determination of nanomolar concentrations of aluminium in seawater by electrothermal atomic absorption spectrometry

The optimization in two steps of seven adjustable parameters through experimental designs associated to an optimal and individualized processing of atomization data allowed to reach a detection limit of 30 ng l(-1) for the quantification of Al in seawater. This detection limit is approximately eightfold lower than that reported previously. Moreover, near the detection limit, the presence of systematic errors, i.e. mathematical miscorrection and weak spectral interferences, which are usually neglected, must be corrected either by using a suitable blank or by estimating such errors. A procedure of highlighting and estimating the mathematical miscorrection and significant Mg and Ca atomic interferences for Al determination at 309.271 nm using a commercial Zeeman apparatus in absence of an Al-free blank is described. Moreover, how to obtain a convenient Al-free blank of seawater is also shown. (C) 2000 Elsevier Science B.V. All rights reserved.