DETERMINATION OF SILICON IN SERUM AND TISSUE BY ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY

Objectives: To employ an electrothermal atomic absorption spectrometry (ETAAS) method with chemical modifiers for the determination of silic on (Si) in serum and tissues. Methods: Si was measured in serum of chr onic hemodialysis patients, and in fibrous breast capsule tissues foll owing silicone-gel implant removal. Tissue was dried, and digested wit h concentrated nitric acid prior to analysis. A chemical modifier, whi ch included lanthanum oxide and ammonium phosphate, was used to dilute the serum, and digested tissue samples (1:4) before atomization. Si w as determined at 251.6 nm in a graphite furnace using an atomic absorp tion spectrophotometer. Results: The method was linear (to 1000 mu g/L ), and precise (CV 5.9% at 281 mu g/L and 8.4% at 73 mu g/L). Recovery of Si in spiked serum and breast tissue samples was between 97-104%. Reference values for women on a normal diet and no exposure to silicon e implants gave serum Si of 30 to 209 mu g/L (n = 60), and breast tiss ue levels of 0.25 to 2.4 mu g/g dry wt (n = 48). Si in breast capsule from women exposed to silicone breast implants varied from 29 to 496 m u g/g dry wt (n = 10). Serum Si in hemodialysis patients (n = 53) rang ed from 900 to 3300 mu g/L. Conclusions: We conclude that our chemical ly modified ETAAS method is suitable for Si determination in normal an d elevated human serum and tissue specimens.