Determination of fenoterol hydrobromide by sequential injection analysis with spectrophotometric detection

A rapid, economical and automated sequential injection spectrophotometric determination of the phenolic sympathomimetic drug, fenoterol hydrobromide, is reported. The method is based on the reaction of fenoterol hydrobromide with 4-aminoantipyrine and potassium hexacyanoferrate and the absorbance of the colored product monitored at 505 nm. Chemical as well as physical SIA 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 parameters, a linear relationship between the relative peak height and concentration was obtained in the range 0.5–40 mg L^-1. The detection limit (as 3(sigma) value) was 0.1 mg L^-1 and precision was 1.8 and 1.6% at 2 and 5 mg L^-1, respectively. As compared to previous works, wide linear range, low detection limit, and highly economical reagent consumption are the advantages of our method.