Silicon concentrations of biological standards

No NIST (National Institutes Standards Technology) standards for the Si concentration of biological materials are available, although Si has been determined for one NIST material by non-NIST personnel, We determined the Si concentrations of NIST materials and a proposed rice-straw (Oryza sativa L.) standard using an autoclave-induced digestion, colorimetric method. We measured 1410 mg Si kg(-1) for NIST material no. 1575, which was not significantly different from five of seven analyses reported in the literature (P > 0.05). Silicon concentrations of NIST and other materials were 2160 mg kg(-1) (no. 1547), 1500 mg kg(-1) (no. 1515), 1920 mg kg(-1) (no, 8412), and 69 300 mg kg(-1) (rice straw).