Flow-injection chemiluminescence detecting sulfite with in situ electrogenerated Mn3+ as the oxidant

By designing a novel flow-through electrolytic cell, the Mn3+ was firstly in situ generated electrochemically on the near surface of the platinum electrode by constant current oxidizing MnSO4 in H2SO4 medium. It was then found that this Mn3+ could oxidize sulfite, which was injected into the electrolytic cell, to produce the strong chemiluminescence (CL) emission signal. Based on this observation, a novel CL method for sulfite is developed in this paper. Under the optimum conditions developed, the CL emission intensity was linear with sulfite concentration in the range 3.0×1.0−7 to 1.0×10−4 mol/l (r=0.9998). The detection limit was 8.0×10−8 mol/l original concentration. The method was successfully used for the determination of SO2 in the air sample.