Ascorbate oxidation by iron: effect of deferoxamine and L1. Increasing concentrations of chelator were added to fresh solutions of phosphate buffer containing 100 μmol/L sodium ascorbate and 30 μmol/L ferric ion. The rate of ascorbate consumption was measured by absorbance spectroscopy at 265 nm at 10 and 40 minutes. (A) Ascorbate oxidation in response to increasing concentrations of deferoxamine (0 to 90 μmol/L). (B) Ascorbate oxidation in response to increasing concentrations of L1 (0 to 180 μmol/L). Shown is a single representative experiment with points indicating the mean ± the standard deviation of nine replicates.