Determination of L-ascorbic acid in fruit and vegetable juices by flow injection with immobilised ascorbate oxidase.
Ascorbate oxidase was immobilised on cyanogen bromide activated-Sepharose 4B and incorporated in a flow-injection system with amperometric detection at a glassy carbon electrode at +0.6 V. On passage through the immobilised ascorbate oxidase a fraction of the L-ascorbic acid was converted into dehydroascorbic acid and the decrease in signal was measured. This could be directly related to the amount of L-ascorbic acid present. The calibration graph was linear over the range 0-400 ng ml(-1) with a correlation coefficient of 0.9994. The detection limit (2 sigma) in phosphate buffer (0.08 M, pH 5.5) was 4.0 ng ml(-1). The relative standard deviation for a 200 ng ml(-1) standard was 1.0% (n = 10) and the sampling throughput was 30 samples h(-1). The method was used for the simple and rapid determination of L-ascorbic acid in fruit and vegetable juice.
Greenway
G M
GM
School of Chemistry, University of Hull, UK.
Ongomo
P
P
D001204:Ascorbate Oxidase; D001205:Ascorbic Acid / Q000032:analysis*; D001628:Beverages / Q000032:analysis*; D004800:Enzymes, Immobilized; D005638:Fruit / Q000032:analysis*; D014675:Vegetables / Q000032:analysis*
D004800:Enzymes, Immobilized; D001204:Ascorbate Oxidase; D001205:Ascorbic Acid