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

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.