A Novel Method for the Assay of Metoprolol by Visible Spectrophotometry using Cobalt Thiocyanate

Abstract

Metoprolol tartrate (MPT) is a selective β1 receptor blocker drug mostly administered in cardiovascular diseases. Due to the highly probable over dosage, a rapid and easy to perform method for the quantitative determination of MPT in biological matrices would be useful in its therapeutic monitoring as well as in intoxication cases. The study presents a validated method for the U.V.-VIS quantitative assay of MPT in bulk and tablet formulations at λmax of 625 n.m. with molar absorptivity of 1.705 × 103 L. mole-1 cm-1 . The parameters targeted for the validation were: linearity, sensitivity, accuracy and precision. The presence of secondary amine group in MPT molecule is the basis for the proposed visible spectrophotometric method. Cobalt Thiocyanate (CTC) has been proved to be a valuable chromogenic reagent for the detection and determination of amino compounds. The coloured species formed is the coordination complex of the drug and the central metal atom of CTC, which is extractable into nitrobenzene from aqueous solution. Formation of blue coloured complex when MPT is treated with CTC due to the presence of secondary amine group in it is the basis in the present investigation. The developed method is more selective, sensitive, reproducible, rapid, cheap and simple than in most of the analogous methods. For these reasons, it can be used in routine analysis and can be applied for the determination of MPT in pharmaceutical formulations and biological samples