Spectrophotometric determination of thiamine hydrochloride using orthogonal polynomials

ANALYSTANALYST Pub Date: DOI: 10.1039/AN9810600960

Abstract

A direct spectrophotometric method for the determination of thiamine hydrochloride in the presence of its degradation products is presented. The method depends upon the use of the combined polynomial method, a modification of Glenn's method of orthogonal functions, to eliminate interferences by degradation products to the absorption spectrum of thiamine hydrochloride. Thus, the coefficient (pw) of the combined polynomial, Pw, calculated over the wavelength range 226–292 nm at 6-nm intervals, is independent of degradation products, is linearly related to the concentration of thiamine hydrochloride and is reproducible, with a relative standard deviation of 0.13–0.54%. The mean recovery for five mixtures of thiamine hydrochloride with degradation products was found to be 100.1 ± 0.6%. When applied to commercial tablets, the results were in good agreement with the USP fluorimetric method. Further, a graph of logarithm of concentration against time for a solution in borate buffer (pH 10) gave a straight line with a slope of –0.022 6 h–1, showing that the method may be used to monitor stability.

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