Spectrofluorometric methods for determination of Thiamine (Vitamin B1) in pharmaceutical formulations

Abstract

Two simple and sensitive methods for determination of Thiamine in pharmaceutical formulations have been reported. The first method was based on the reaction of Thiamine with 1,2-Naphthoquinone-4-sulphonate sodium salt (NQS) in basic medium (pH = 11) giving a fluorescent product which shows excitation and emission maxima at 390 and 460 nm respectively. The second method was based on the reaction of Thiamine with 7-chloro-4-nitro-2,1,3-benzoxaldizole (NBD-Cl) in buffered medium (pH = 10.5) leading to the formation of highly fluorescent adduct which is measured at 562 nm after excitation at 472 nm. All factors that affect the reaction was studied and optimized, and under optimum conditions linear relationship with good correlation coefficient (0.999) relating to both reagents was obtained in the concentration ranges 0.1 – 1.0 and 0.2 – 1.0 µg/mL for NQS and NBD-Cl methods respectively. The limit of detection was found to be 0.020 µg/mL for the two methods. The Precision of the methods were satisfactory with relative standard deviation (RSD) of less than 2. The proposed methods were successfully applied to the analysis of Thiamine in pharmaceutical formulations with good accuracy; the recovery percentages ranged from 98.90±0.49 –101.39±1.02 %. The results were in good agreement with those of the reported methods.