ENZYMATIC METHOD FOR MEASUREMENT OF ASCORBATE-2-PHOSPHATE

An enzymatic assay to measure ascorbate phosphate is described. The procedure utilizes acid phosphatase [EC 3.1.3.2] to hydrolyze the phosphate group of AsP, liberating ascorbic acid. The ascorbic acid is assayed by utilizing its ability to reduce ferric ion to the ferrous state and then complexing the ferrous ion with α,α′-dipyridyl. Absorbance of the α,α′-dipyridyl complex is measured spectrophotometrically at 525 nm. The assay has a quantitative sensitivity lower limit of 0.0625 mmole/liter. It is reliable, safe, and has a coefficient of variation of less than 10% when triplicate samples are run, and all samples produce an optical density greater than 0.2 absorbance units. © 1978.