Flow injection chemiluminescence determination of loxoprofen and naproxen with the acidic permanganate-sulfite system

A novel flow injection chemiluminescence (CL) method for the determination of loxoprofen and naproxen was proposed based on the CL system of KMnO₄, and Na₂SO₃ in acid media. The CL intensity of KMnO₄-Na₂SO₃ was greatly enhaneed in the presence of loxoprofen and naproxen. The mechanism of the CL reaction was studied by the kinetic proecss and UV-vis absorption and the conditions were optimized. Under optimized conditions, the CL intensity was linear with loxoprofen and naproxen concentration in the range of 7.0 × 10^?8 – 1.0 × 10^?5 g/mL and 2.0 × 10^?7 – 4.0 × 10^?6 g/mL with the detection limit of 2.0 × 10^?8 g/mL and 3.0 × 10^?8 g/mL (S/N = 3), respectively. Thc relative standard deviations were 2.39% and 1.37% for 5.0 × 10^?7 g/mL naproxen and 5.0 × 10^?7 g/mL loxoprofen (n = 10), respectively. The proposed method was satisfactorily applied to thc determination of loxoprofen and naproxen in pharmaceutical preparations.