Organic media enhanced spectrofluorimetric determination of L-ascorbic acid

A novel spectrofluorimetric method for the determination of L-ascorbic acid is proposed. It is based on the inhibition of L-ascorbic acid on the formation of 2,3-diaminophenazine, which is an oxidation product ofo-phenylenediamine catalyzed by laccase. The fluorescence (at λcx/λcm=464 nm /530 nnm) was enhanced strongly in the presence of organic media. The mechanism ofo-phenylenediamine oxidation reaction catalyzed by laccase in the presence of L-ascorbic acid is discussed. L-ascorbic acid is determined in the ethanol, 1,4-dioxane and acetone over the linear range of 4.0×10−7≈1.2×10−4 mol/L, 4.0×10−7≈8.0×10−5 mol/L and 4.0×10−7≈1.0×10−4 mol/L with a detection limit of 1.20×10−5 mol/L, 1.19×10−5 mol/L and 1.24×10−8 mol/L, respectively. The method has been successfully applied to the simple and rapid determination of L-ascorbic acid in pharmaceuticals and milk powder.