Noble metal modifiers for antimony determination by graphite furnace atomic absorption spectrometry in biological samples

The use of palladium, iridium or rhodium as a modifier in graphite furnace atomic absorption spectrometry was investigated for the determination of antimony in eluent fractions from high-performance liquid chromatography separation of clinical samples. The separation of albumin and transferrin at the physiological pH was carried out by ion chromatography on a Cosmogel DEAE column. As an eluent, 0.01 mol l(-1) Tris-HCl in NaCl 1 mol l(-1) gradient was used. Several fractions-of 0.5 mi each were collected and the concentration of antimony was determined off-line by GFAAS. Palladium, iridium and rhodium effectively stabilise antimony in an aqueous standard solution. In the presence of proteins, Tris-HCl buffer and NaCl, rhodium loses its stabilising performance. However, palladium and iridium were found to be efficient with respect to stabilisation of antimony up to 1500 degreesC in matrix-containing solutions.