Deproteinization of blood serum by acid treatment and microwave irradiation for the determination of aluminium by electrothermal atomic absorption spectrometry

A method of deproteinizing serum was employed to reduce the protein concentration in the determination of aluminium by electrothermal atomic absorption spectrometry, The procedure combines the action of microwave irradiation with acids, at a concentration 10 times lower than that in the usual acid deproteinization methods, and promotes a protein reduction > 99% with a small dilution factor (1 + 1). The best results with respect to aluminium determination were obtained with trichloroacetic acid at a concentration of 1.0%. Before the deproteinization procedure for recovery measurements, serum samples were submitted to an incubation treatment at 37 degrees C to bond aluminium ions to the proteins. The proposed method was compared with the usual deproteinization with acids for the separation of proteins, and for the determination of aluminium with direct injection of diluted serum samples into the graphite furnace. The regression for the correlation analysis of the proposed method and the direct determination of aluminium, applied to the analysis of 20 serum samples, indicated that the deproteinization procedure is efficient and generates comparable results. The reduction of the proteins allowed the use of a simple and fast graphite furnace heating programme for the analysis of serum samples without matrix interferences.