Determinação de alumínio e ferro em fluidos pós-hemodiálise empregando voltametria e decomposição de amostras com radiação ultravioleta

Abstract

The simultaneous determination of Al(III) and Fe(III) in post-hemodialysis fluids was investigated by the Adsorptive stripping voltammetry (AdSV) of solochrome violet (SVRS) metal complexes. The analytes build electrochemically active complexes with SVRS reagent in acetate buffered medium at pH 4.6. The adsorption of the complexes on the mercury electrode (HMDE) was investigated by out of phase altenating current voltammetry in presence of the main matrix interfering species, urea, creatinine, glucose, uric and oxalic acids. The competitive action of the matrix relatively to Al(III) and Fe(III) SVRS complexes formation apart of the HMDE electrode was assessed by molecular spectrometry. The interference rank uric acid > urea = oxalic acid > creatinine was stablished. Sample digestion by UV irradiation was investigated to overcome the matrix interference on the electrodic reaction and competition toward the analytes as well. Two hours digestion time at 90 °C in H2O2 acidic solution was enough to assay by AdSV Al(III) and Fe(III) as SVRS complexes in 1:1 diluted real post-hemodialysis samples. The proposed method was valid for samples containing or not Desferrioxamine B. It was tested to assay Al(III) and Fe(III) in 36 real post-hemodialysis samples obtained from the university hospital. Detection limits of 1.4 and 1.8 μg L-1 were calculated for Al(III) and Fe(III), respectively. Recoveries ranging from 88.1 to 106.7% were obtained from spiking experiments.