Determination of silicon in serum and tissue by electrothermal atomic absorption spectrometry

To employ an electrothermal atomic absorption spectrometry (ETAAS) method with chemical modifiers for the determination of silicon (Si) in serum and tissues.

Si was measured in serum of chronic hemodialysis patients, and in fibrous breast capsule tissues following silicone-gel implant removal. Tissue was dried, and digested with concentrated nitric acid prior to analysis. A chemical modifier, which included lanthanum oxide and ammonium phosphate, was used to dilute the serum, and digested tissue samples (1:4) before atomization. Si was determined at 251.6 nm in a graphite fumace using an atomic absorption spectrophotometer.

The method was linear (to 1000 micrograms/L), and precise (CV 5.9% at 281 micrograms/L and 8.4% at 73 micrograms/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 silicone implants gave serum Si to 30 to 209 micrograms/L (n = 60), and breast tissue levels of 0.25 to 2.4 micrograms/g dry wt (n = 48). Si in breast capsule from women exposed to silicone breast implants varied from 29 to 496 micrograms/g dry wt (n = 10). Serum Si in hemodialysis patients (n = 53) ranged from 900 to 3300 micrograms/L.

We conclude that our chemically modified ETAAS method is suitable for Si determination in normal and elevated human serum and tissue specimens.