DEPROTEINIZATION OF BLOOD-SERUM BY ACID TREATMENT AND MICROWAVE IRRADIATION FOR THE DETERMINATION OF ALUMINUM BY ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY

A method of deproteinizing serum was employed to reduce the protein co ncentration in the determination of aluminium by electrothermal atomic absorption spectrometry, The procedure combines the action of microwa ve irradiation with acids, at a concentration 10 times lower than that in the usual acid deproteinization methods, and promotes a protein re duction > 99% with a small dilution factor (1 + 1). The best results w ith respect to aluminium determination were obtained with trichloroace tic acid at a concentration of 1.0%. Before the deproteinization proce dure for recovery measurements, serum samples were submitted to an inc ubation treatment at 37 degrees C to bond aluminium ions to the protei ns. The proposed method was compared with the usual deproteinization w ith acids for the separation of proteins, and for the determination of aluminium with direct injection of diluted serum samples into the gra phite furnace. The regression for the correlation analysis of the prop osed method and the direct determination of aluminium, applied to the analysis of 20 serum samples, indicated that the deproteinization proc edure is efficient and generates comparable results. The reduction of the proteins allowed the use of a simple and fast graphite furnace hea ting programme for the analysis of serum samples without matrix interf erences.