SILICON MEASUREMENT IN BONE AND OTHER TISSUES BY ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY

A method for the determination of silicon in bone and soft tissues using electrothermal atomic absorption spectrometry is described. Small wet biopsy samples are digested with concentrated nitric acid at 90-degrees-C. The atomization signal of silicon in pyrolytic graphite coated graphite tubes is markedly enhanced by the addition of a lanthanum-calcium mixture in the test solution. No L'vov platform was used. Ammonium dihydrogenphosphate is added to the soft tissue digestate solution to eliminate the interferences arising from the biological matrices, while tartaric acid disodium salt is used as a chemical modifier for the analysis of bone digest. Concentrations of silicon in the test solutions are determined against an aqueous standard calibration curve. The characteristic mass is 37 pg (integrated absorbance signal equal to 0.0044 s). For the sample digestion liquids, the within- and between-run relative standard deviations are <5.5%. The accuracy of the method is evaluated by determining the recovery of silicon added to the sample solutions and the results are close to 100%. The detection limits for silicon in bone and other tissues are 0.90 and 0.14 mug g-1 wet mass, respectively. Examples of silicon contents found in bone, brain, kidney, liver, spleen and heart of laboratory rats are given.