An Indirect Spectrophotometric Method for the Determination of Silicon in Serum, Whole Blood and Erythrocytes

Abstract

An indirect method for the determination of silicon in blood samples has been developed. The proposed method overcame interference from a large amount of salts and phosphate in blood samples, and enabled us to determine the silicon contents in serum and whole blood by the same operation. After blood samples were digested by microwave heating, silicon, present as silicate in the sample solution, was reacted with molybdate to form a silicomolybdate complex. The complex was then separated from unreacted molybdate by a cation-exchange resin column. The molybdate liberated from the complex was spectrophotometrically determined in place of silicon. Since the method is not affected the composition of matrices between serum and whole blood, it could achieve good precision and accuracy, and could also estimate the silicon contents in erythrocytes from those in serum and whole blood. The sensitivity of the method was almost equal to that of the conventional silicomolybdenum blue method, and the calibration curve was linear up to 50 μmol l^-1 of silicon with a detection limit of 1.1 μmol l^-1 in whole blood. The mean concentrations of silicon in five healthy subjects were 11 μmol l^-1 for serum, 28 μmol l^-1 for whole blood and 50 μmol l^-1 for erythrocytes. Thus, the obtained distribution ratio between serum and erythrocytes was in the range of 0.15 - 0.39, and was found to be included in a narrow range.