Sequential injection spectrophotometric determination of ritodrine hydrochloride using 4-aminoantipyrine

A sequential injection spectrophotometric determination of ritodrine hydrochloride is described. The method is based on the condensation of aminoantipyrine with phenols in the presence of an alkaline oxidizing agent to yield a pink coloured product the absorbance of which is monitored at 503 nm. Different sequential injection analysis (SIA) parameters including reagent concentrations have been optimised and used to obtain the analytical figures of merit. A linear concentration range of 3.1–123.5 μmol L−1 and a detection limit (as 3σ-value) of 1.0 μmol L−1 were obtained. The precision was 2.4 and 2.3% relative standard deviation (R.S.D.) at 6.2 and 15.4 μmol L−1, respectively. This method is superior over previously reported ones in terms of linear range, short analysis time, high sample throughput, excellent reagent economy and minimum waste generation.