The Silicate Structure Analysis of Magnesium Silicate Antacid by the Trimethylsilylation Method

Composition and degree of polymerization of polysilicic acids in magnesium silicates were studied by the trimethylsilylation method. The trimethylsilylated derivatives of silicic acids obtained by acid hydrolysis of the silicates were separated into soluble and insoluble fractions. Orthosilicic acid and a few species of polysilicic acids were determined by gas-liquid chromatography in the soluble fraction. The results are as follows : monosilicic acids (0.16-0.96%), disilicic acids (0.02-0.31%), trisilicic acids (-0.06%), cyclic tetrasilicic acids (-0.11%), the other soluble polysilicic acids (0.35-1.45%), and insoluble polysilicic acids (75.78-82.07%). These results apparently suggest that, when magnesium silicate is hydrolyzed in gastric juice, most of silicic acids produced may lead to insoluble silica gel and the other, such as orthosilicic acid and several polysilicic acids with low degree of polymerization, may disperse in gastric juice. Possible absorption of silicic acids from digestive tracts following oral administration of the antacid was discussed.