Flow injection chemiluminescence determination of naproxen based on KMnO4–Na2SO3 reaction in neutral aqueous medium

A simple, rapid and sensitive flow injection chemiluminescence (CL) method is described for the determination of naproxen. It was found that strong CL signal was generated when naproxen was mixed with KMnO4 and Na2SO3 in neutral aqueous medium. Under the optimum experimental conditions, the CL intensity was linearly related to the concentration of naproxen from 4.0 × 10−9 to 1.0 × 10−6 g mL−1 (r = 0.9993). The detection limit was 2 × 10−9 g mL−1 naproxen, the relative standard deviation for 1.0 × 10−7 g mL−1 naproxen solution was 1.5% (n = 11) and the sampling frequency was 120 h−1. The method was applied to the determination of naproxen in pharmaceutical preparation with satisfactory results. The mechanism of CL reaction was discussed briefly.