SILICON DETERMINATION IN SERUM BY GRAPHITE-FURNACE AAS WITH PD-RH MODIFIER

A mixture of palladium and rhodium salts was examined as a chemical mo difier for silicon determination in biological samples. The pretreatme nt of the graphite furnace with the Pd-Rh modifier allows determinatio n of silicon in serum after 20 fold dilution with a detection limit of 2 ng/ml (for 20 mu l) using calibration against matrix-free reference solutions. The transversely heated graphite atomizer (THGA) was used to fulfil the requirement of the stabilized temperature furnace (STPF) concept of isothermal condition, of special importance for Si atomiza tion. The palladium-rhodium modifier was used to reduce the formation of silicon oxide and carbide providing improved sensitivity. In analyt ical conditions, even without addition of air in the pyrolysis step th e background for the serum samples is less than 0.1 A. The proposed me thod has been applied to the determination of silicon in serum of norm al healthy individuals.