Electrothermal atomic absorption spectrometric determination of aluminum in serum with a new technique for protein precipitation.

We have studied the electrothermal atomic absorption measurement of aluminum in serum samples by direct analysis with standard additions and the use of a matrix modifier. We have also measured aluminum by analysis of the supernate after pretreatment of serum with concentrated nitric acid to precipitate proteins, and have compared the results obtained by these two techniques. Both appear to eliminate interferences arising from the serum matrix. We quantified the aluminum by utilizing a stabilized temperature (L'vov) platform. Within-run precision (CV) for the standard-additions method was 16.6% (means = 6.5 micrograms/L) and 6.0% (means = 86.8 micrograms/L) and for the protein precipitation method was 10.1% (means = 10.9 micrograms/L) and 4.2% (means = 88.5 micrograms/L). Linearity of the standard curve extended from 0 to 120 micrograms/L for the standard-additions method and from 0 to 100 micrograms/L for the protein precipitation method. Samples from 38 patients were analyzed by both techniques, and linear regression analysis yielded the equation y (protein precipitation) = 1.02 X (standard additions) + 2.04.