Catalytic Activity of Thiacalix[4]arenetetrasulfonate Metal Complexes on Modified Anion-Exchangers for Ascorbic Acid Oxidation

The catalysis of ascorbic acid (AsA) oxidation by anion-exchangers modified with metal complexes of thiacalix[4]arenetetrasulfonate (Me-TCAS[4](A-500), Me=Mn3+, Fe3+, Co3+, Ce4+, Cu2+, Zn2+, Ni2+, and H-2) were investigated. Me-TCAS[4](A-500) (Me=Mn3+, Fe3+, Ce4+, and Cu2+) all exhibited the ability to catalyze the oxidative reaction of AsA to dehydroascorbic acid. However, in the presence of high concentrations of AsA, only Cu2+-TCAS[4](A-500) was capable of complete oxidation of the acid. Moreover, after six repeat uses, Cu2+-TCAS[4](A-500) maintained high and relatively constant catalytic activity. Prior treatment of glucose solutions with Cu2+-TCAS[4](A-500), even in the presence of high AsA concentrations, enabled the satisfactory determination of glucose without interference by AsA. Cu2+-TCAS[4](A-500) will therefore be applicable as an artificial substitute for ascorbate oxidase, and may be useful as a means to eliminate AsA interference during the analysis of vital compounds such as glucose and uric acid.