Chemiluminescence of indole compounds based on oxidation with singlet oxygen generated chemically by the sodium molybdate–hydrogen peroxide system

Abstract

Singlet oxygen generated by the reaction of MoO₄ ²⁻ with H₂O₂ was used for the luminous oxidation of indole compounds in unbuffered solution. The speed of the chemiluminescent reaction is slow at ambient reaction temperature and appears to depend on the rates of both the oxidation with and the generation of singlet oxygen. At elevated reaction temperatures, melatonin was detected most sensitively with the detection limit of 10⁻⁹ M in both batch and flow injection methods. Immobilization of the MoO₄ ²⁻ catalyst on strongly basic anion-exchange resins may permit flow-through sensing and thus a simple post-column detection of melatonin and other indole compounds.