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

Abstract

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 H₂) 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.