Stopped-flow kinetic determination of acetaminophen by oxidation with a 1,10-phenanthroline/iron(III)complex

A stopped-flow method for the determination of acetaminophen based on its oxidation with a 1,10-phenanthroline/iron (III) complex is described. The reaction is followed by measuring the initial rate of change of the absorbance of the ferroin formed at 510 nm, which is proportional to the acetaminophen concentration. The linear range of the determination is 0.25–25.0 μg ml^?1 and the relative standard deviation is 2.6%. Sample throughput is 60 h^?1 (triplicate runs). The method is simple and rapid and unaffected by the presence of most other drugs and excipients. Analysis of pharmaceutical samples showed excellent correlation with the nominal values.