Indirect Spectrophotometric Determination of Thiamine in Pharmaceutical Preparations

概要

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An indirect, sensitive spectrophotometric method for the assay of thiamine is described. The procedure is based on the formation of a mercaptide by thiamine, with a known excess of silver ions in a buffered medium of pH 9.0±0.1. The unreacted silver ions are determined by the formation of an ion-pair complex with 1,10-phenanthroline and 2,4,5,7-tetrabromofluorescein, which shows an absorption maximum at 550 nm. The absorbance is found to decrease linearly with increasing concentrations of thiamine, which is corroborated by the calculated correlation coefficient value of -0.998. The system obeys Beer's law for 0-25 μg of thiamine in an overall aqueous valume of 10 ml. The molar absorptivity and relative standard deviation (RSD) were calculated to be 7.8×10^4 lmol^<-1> cm^<-1> and 2.5% (n=10), respectively. The proposed method was applied successfully to the determination of thiamine in pharmaceutical preparations. The reliability of the assay was established by parallel determination by the standard thiochrome method and recovery studies.
公益社団法人日本薬学会の論文
1997-12-15