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

Simple, sensitive and stable fluorometric sensors based on the polyoxotungstate intrinsic peroxidase (Na-10[-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 center dot OH radicals decomposed from H2O2 under the catalysis of Na-10[alpha-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 x 10(-8) to 1.6 x 10(-6), 1.6 x 10(-6) to 1 x 10(-4), and 1 x 10(-5)to 2.5 x 10(-4) M with BA, TH, and HPPA as substrates, respectively. Detection limits for the three systems were found to be 6.7 x 10(-9), 2.2 x 10(-7) and 9.6 x 10(-6) M (3 sigma), 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.