Study On The Electrochemical Oxidation Of Melatonin And Its Electrochemical Determination

The irreversible electrochemical oxidation of melatonin(MLT) was studied by cyclic voltammetry and bulk electrolysis with coulometry in this paper. The experimental results have revealed that its electrochemical oxidation was controlled by weakly adsorbing and the diffusion corporately. The number of electron transfer equals to 2. The linear sweep voltammetry(LSV) could be applied in the determination of melatonin with very high sensitivity. In the range from 2.0×10~10mol/L to l.0×10~6mol/L, the current of oxidation peak of melatonin linearly responded upon its concentration. The detecting limit is as low as 10~10mol/L order of magnitude of the concentration. This method could be used in the determination of melatonin in the capsules with satisfactory results.In the borate buffer solution of pH6.7, the melatonin quenched the H2O2 enhanced electrochemiluminescense(ECL) of luminol because of the annihilation to the oxygen free radicals. It could be sensitively determined by this method. In the range from 1.0×10~14mol/L to 7.0×10~9mol/L, the ECL luminous intensity linearly decreased upon the concentration of MLT . The detecting limit is as low as 1.0×10~14mol/L, and the capsule samples have been determined with satisfactory results. It should be another sensitive and reliable method for the determination of melatonin.