Determination of isoxsuprine hydrochloride by sequential injection visible spectrophotometry

An automated sequential injection (SI) spectrophotometric method for the determination of isoxsuprine hydrochloride is described. The method is based on the condensation of aminoantipyrine with phenols (isoxsuprine hydrochloride) in the presence of an alkaline oxidizing agent (potassium hexacyanoferrate) to yield a pink colored product, the absorbance of which is monitored at 507 nm. Chemical as well as physical SI parameters that affect the signal response have been optimized in order to get better sensitivity, higher sampling rate and better reagent economy. Using the optimized aforesaid parameters, a linear relationship between the relative peak height and concentration was obtained in the range 1-60 mg l-1. The detection limit (as 3σ value) was 0.3 mg l-1 and precision was 1.4% and 1.6% at 5 and 10 mg l-1, respectively. As compared to previous reports, wide linear range, low detection limit, and highly economical reagent consumption are the advantages of this automated method.