Flow injection chemiluminescence determination of paracetamol

A simple chemiluminometric method using flow injection has been developed for the determination of paracetamol (acetaminophen), based on the chemiluminescence produced by the reduction of tris(2,2'-bipyridyl)ruthenium(III). The latter is obtained by oxidation of tris(2,2'-bipyridyl)ruthenium(II) by potassium permanganate in dilute sulphuric acid in the presence of paracetamol. A standard or sample solution was injected into the ruthenium(II) stream (flow rate 1.5mlmin(-1)) which was then merged with potassium permanganate in dilute sulphuric acid stream (flow rate 0.5mlmin(-1)). The chemiluminescence intensity is enhanced by the presence of manganese(II) ions. Under the optimum conditions, a linear calibration graph was obtained over the range of 0.3-50.0mugml(-1) and the detection limit was 0.2mugml(-1) (s/n=3). The relative standard deviation of the proposed method calculated from 20 replicate injections of 5.0mugml(-1) paracetamol was 1.1%. The sample throughput was 90h(-1). The method was successfully applied to the determination of paracetamol in commercial pharmaceutical formulations.