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 enhanced in the presence of loxoprofen and naproxen. The mechanism of the CL reaction was studied by the kinetic process 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 X 10(-8) - 1.0 x 10(-5) g/mL and 2.0 x 10(-7) - 4.0 X 10(-5) g/mL with the detection limit of 2.0 x 10(-8) g/mL and 3.0 x 10(-8) g/mL (S/N = 3), respectively. The relative standard deviations were 2.39% and 1.37% for 5.0 x 10(-7) g/mL naproxen and 5.0 x 10(-7) g/mL loxoprofen (n = 10), respectively. The proposed method was satisfactorily applied to the determination of loxoprofen and naproxen in pharmaceutical preparations.