Selective Microanalysis of Substituted Anthracenes by Electrogenerated Chemiluminescence

Abstract

The utility of electrogenerated chemiluminescence (ECL) for an analytical purpose is described. As the ECL analysis uses a certain type of electrolysis for the observation of chemiluminescence at the electrode surface, a proper selection of the applied potential region and the frequency of square wave allows us to determine selectively a desired trace component in the presence of other major components. The basic experimental procedures have now been established for a model system of a mixture of substituted anthracenes 9, 10-dicyanoanthracene (DCA), 9, 10-diphenylanthracene (DPA) and 9, 10-dipropylanthracene(DPrA ). By fixing the negative side of the applied square-wave potential at the reduction potential of DCA, the positive potential was swept linearly to the positive direction. The chemiluminescence was observed above the oxidation potential of DPrA and DPA. The electron transfer reaction was thus shown to be possible between anion radicals of DCA and cation radicals of DPrA or DPA. As the ECL spectrum coincides with the fluorescence spectrum of DCA, the triplet-triplet annihilation reaction of excited state of DCA is considered to be responsible for the emission. From a viewpoint of analytical determination, it is interesting to detect a trace am ount of DPA in the presence of large quantity of DPrA because of a similar fluorescence spectrum of both compounds. By choosing a suitable experimental condition of ECL, it is possible, for example, to determine 0.2μmol/l of DPA in the presence of 0.2 mmolg of DPrA.