Fluorometric enhancement of the detection of H2O2 using different organic substrates and a peroxidase-mimicking polyoxometalate

Abstract

Simple, sensitive and stable fluorometric sensors based on the polyoxotungstate intrinsic peroxidase (Na₁₀[α-SiW₉O₃₄]) induced fluorescent enhancement of benzoic acid (BA), thiamine (TH) and 3-(4-hydroxyphenyl)propionic acid (HPPA) for the detection of hydrogen peroxide (H₂O₂) are developed for the first time. In three assays, the three non-fluorescent substrates BA, TH and HPPA were oxidized with the ·OH radicals decomposed from H₂O₂ under the catalysis of Na₁₀[α-SiW₉O₃₄] under basic pH conditions. The optimal conditions for the detection of H₂O₂ were evaluated and possible mechanisms are also discussed. The fluorescence intensity increases were linearly related to the concentration of H₂O₂ in the ranges 1 × 10⁻⁸ to 1.6 × 10⁻⁶, 1.6 × 10⁻⁶ to 1 × 10⁻⁴, and 1 × 10⁻⁵to 2.5 × 10⁻⁴ M with BA, TH, and HPPA as substrates, respectively. Detection limits for the three systems were found to be 6.7 × 10⁻⁹, 2.2 × 10⁻⁷ and 9.6 × 10⁻⁶ M (3σ), respectively. The RSD values ranged from 2.57% to 4.66%, 0.82% to 4.06%, and 1.08% to 2.75%, respectively. The rates of recoveries were between 99.73% and 113.06%, 95.20% and 104.22%, and 95.28% and 128.76%, respectively. Moreover, the effects of interference were studied. The proposed work was successfully applied to the determination of H₂O₂ in water and a sensitive, rapid and easy to operate assay was built, which has great potential applications in environmental science.