Highly sensitive spectrofluorimetric determination of ascorbic acid based on its enhancement effect on a mimetic enzyme-catalyzed reaction

A spectrofluorimetric method for determining ascorbic acid based on its enh ancement on the fluorescence of the mimetic enzyme-catalyzed oxidation of p -cresol by hydrogen peroxide was proposed. The optimal conditions were foun d. The influence of different buffers and concentrations on the relative fl uorescence intensity was tested, which showed that the enhancement effect w as the most evident in NH3-NH4Cl solution, especially at high NH3 concentra tion. The reaction product was monitored fluorimetrically, with a 3 sigma d etection limit of 3.45 x 10(-10) mol l(-1) ascorbic acid. A liner calibrati on graph was obtained over the ascorbic acid concentration range 1 x 10(-9) -8 x 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 x 10(- 8) mol l(-1) was 1.2% (n=9). The varying influence of different concentrati ons of ascorbic acid on the redox reaction was observed through 3D fluoresc ent spectra and progress curves. (C) 2000 Elsevier Science B.V. All rights reserved.