Colorimetric and fluorimetric assay of azintamide in pharmaceutical formulations

ABSTRACT

Simple, accurate and sensitive colorimetric and fluorimetric methods are described for the determination of the choleretic drug azintamide. The colorimetric methods are based on thionine formation, a blue colored compound, absorbing maximally at 600 nm. Thionine is formed by heating acidic azintamide solution with zinc powder in presence of p-phenylenediamine and then addition of iron [3] ammonium sulfate solution. The fluorimetric method is based on measurement of the previously formed thionine after extraction with n-butanol at 550 and 620 nm excitation and emission wave lengths, respectively. The colorimetric and fluorimetric methods were applicable over the concentration ranges of 50-250 and 10-50 ug ml-1, respectively. These methods were further applied for analysis of azintamide in pharmaceutical preparations and the results were in agreement with those obtained from direct UV spectrophotometric method: