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ABSTRACT: A new analytical method for the determination of uric acid (UA) by the perturbation of UA on the Belousov-Zhabotinsky oscillating reaction is proposed. The method is based on the linear relationship between the changes in the oscillating period and the concentration of UA. The calibration curve is linear over the range of 2.0 x 10(-5) to 5.0 x 10(-4)M, with a detecting limit of 3.28 x 10(-6)M. The method features good precision (R.S.D.: 3.59%) and excellent throughput (10samplesh(-1)). The possible mechanism of the perturbation of UA on the oscillating reaction is discussed.
Talanta 03/2005; 65(3):799-805. · 3.79 Impact Factor
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ABSTRACT: The nanometer-sized ZnO was prepared through the sol-gel method. Its average particle diameter, determined by TEM, was 20-30 nm. The specific surface area was determined to be 22 m2 g(-1) by BET. The photodegradation mechanism of Rhodamine dyes on nanometer-sized ZnO was studied by dynamic molecular spectra, and the results showed that the photodegradation of Rhodamine dyes obeyed the rules of a pseudo first-order kinetic reaction. The rate constant k of the degradation of Rhodamine B (RB) and butyl-Rhodamine (BR) were 0.0128 and 0.0154 min(-1), respectively, and the half period t(1/2) were 60 and 52 min, respectively. The photodegradation reaction conditions were optimized. After intermixing with silver, the photodegradation efficiency was greatly improved. A life-span test showed that nanometer-sized ZnO had a long life-span.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 07/2004; 60(7):1617-24. · 2.10 Impact Factor
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ABSTRACT: A spectrofluorometric method for the determination of ascorbic acid (AA) based on its activation on the hemoglobin-catalyzed reaction was proposed. The fluorescence intensity of the product was measured under the optimal experimental conditions, i.e. 4.0 x 10(-6) M H2O2, 6.0 x 10(-5) M p-cresol, 1.2 M NH3-NH4Cl (pH 10.4) and 2.0 x 10(-7) M hemoglobin. The order of additions of the reagents was also studied. The activation of AA was found to be associated with a high ammonia concentration. The linear range of the method was 9.0 x 10(-10)-3.6 x 10(-8) M of AA. The detection limit was calculated to be 3.0 x 10(-10) M. The relative standard deviation of this method is 1.6% at 7.0 x 10(-9) M for 11 determinations.
Analytical Sciences 10/2002; 18(9):977-80. · 1.25 Impact Factor
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Analytical Letters 06/1998; 31(8):1337-1349. · 1.02 Impact Factor
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ABSTRACT: Thiamine in living human bodies exists mainly as diphosphate, which works as a co-enzyme of the sugar metabolism system (active vitamin B1). Thiamine deficiency brings many clinically significant problems, such as dysphoria, quadriplegia and dyspepsia. Intrinsic fluorescence has an advantage over the extrinsic fluorescence of an unperturbed environment during investigation, especially in complex systems such as biological cells and tissues. Cellular fluorescence provides a sensitive index of the functional state of a living cell (1). Different amounts of thiamine were added to culture medium and the fluorescence of tryptophan and NADH from yeast was determined. When the thiamine concentration was greater than 0-0.16 microg/mL, the intensity of tryptophan fluorescence increased linearly, whereas the NADH fluorescence decreased. When the thiamine concentration was above 0.24 microg/mL, the fluorescence of tryptophan and NADH was almost unchanged. We concluded that low thiamine concentration in culture medium had a large effect on the growth of Saccharomyces cerevisiae and possible reasons are discussed.
Luminescence 20(3):216-9. · 1.73 Impact Factor
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ABSTRACT: A spectrofluorimetric method for determining ascorbic acid based on its enhancement on the fluorescence of the mimetic enzyme-catalyzed oxidation of p-cresol by hydrogen peroxide was proposed. The optimal conditions were found. The influence of different buffers and concentrations on the relative fluorescence intensity was tested, which showed that the enhancement effect was the most evident in NH3–NH4Cl solution, especially at high NH3 concentration. The reaction product was monitored fluorimetrically, with a 3σ detection limit of 3.45×10−10 mol l−1 ascorbic acid. A liner calibration graph was obtained over the ascorbic acid concentration range 1×10−9–8×10−8 mol l−1, with a correlation coefficient of 0.9997 (n=18). The relative standard derivation at an ascorbic acid concentration of 3×10−8 mol l−1 was 1.2% (n=9). The varying influence of different concentrations of ascorbic acid on the redox reaction was observed through 3D fluorescent spectra and progress curves.
Analytica Chimica Acta.
