Determination of silicon in biological samples by ICP-OES after non-oxidative decomposition under alkaline conditions.

A non-oxidative alkaline sample digestion procedure using tetramethylammonium hydroxide and a high pressure, microwave assisted autoclave digestion system was developed. The silicon concentrations of the digested samples were measured by inductively coupled axial plasma optical emission spectrometry (ICP-OES). Details of the digestion conditions as well as the optimised instrumental parameters for ICP-OES are described. The method was developed and tested using silicon-spiked ascorbic acid and applied to samples of animal tissue and organs. The total silicon content of two different reference materials, NIST 1577b Bovine liver and BCR 184 Bovine Muscle having neither certified nor informational values for Si was determined. The results obtained are compared with the results of independent methods such as wavelength dispersive x-ray fluorescence spectrometry (WDXRF) and solid sampling electrothermal atomic absorption spectrometry (ETAAS). The method described achieves a limit of detection of 2 mg kg(-1) using 100 mg of solid biological or organic material and covers a concentration range of up to 500 mg kg(-1).