Motofumi TOKUNO
Development of dye nanoparticle coated test strip for the detection of hydrogen peroxide
Yukiko Takahashi
Colorimetric analysis of hydrogen peroxide based on ternary complex formation of metal chelate with hydrogen peroxide is known as a highly sensitive and selective method of detecting hydrogen peroxide in an environmental sample. In this study, new dye nanoparticle coated test strips (DNTSs) for hydrogen peroxide were developed by loading with metal complexes capable of generating a colored ternary complex with hydrogen peroxide. Four complexes, Ti (¸) -4- (2'-pyridylazo) resorcinol (Ti-PAR), Ti (¸) -xylenol orange (Ti-XO), Ti (¸) -chromazurol S (Ti-CAS) and V (¹) -XO (V-XO) were used.
The nanocomposite dispersion was prepared by mixing 10 ml of 5 ¦ÌM complex solution and 70 ¦Ìl of 25 mg/ml Latex-N(CH3)3+ with 2.5 mM boric acid buffer (pH 8.6) or acetate acid buffer (pH 4.7). Then, by passing the solution through a membrane filter under 0.1 MPa suction pressure at 24¡î, these nanocomposite were coated as a thin layer onto the surface of the filter based on surface filtration. DNTSs were immersed into 20 ml of 9.1 mM hydrogen peroxide for 24 hours. After immersion test, the reflection absorption spectra of the DNTSs were recorded on the array spectrophotometer MPCD-3700.
The reflection absorption spectrum of Ti-PAR DNTS changed with the concentration of hydrogen peroxide as the absorption spectrum of Ti-PAR in an aqueous solution. The color of Ti-PAR complex changed yellow to pink as the absorption maximum shifted from 412 nm to 518 nm. The saturation of the color reaction took more than 6 hours. When the sample solution was kept at 45¡î, the intensity at 518 nm increased until 120 minutes and after that gradually decreased. It suggested that heating sample solution at 45¡î accelerates the ternary complex formation, however, long time heating more than 120 minutes conduces color fade-out and the decomposition of Ti-PAR complexe. The calibration curves for hydrogen peroxide were obtained when the sample volume was 20 ml and expressed as I = 0.430 + 0.263c - 0.179c2(I: intensity at 518 nm, c: concentration of hydrogenperoxide) (correlation efficient¡ä0.996) (quantitativw range: 0~0.7 mM), and the 3¦Ò detection limit was calculated to be 39 ¦ÌM by the array spectrophotometer at 518 nm.
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