Not according to Pat Gainer, see post#20.The phenidone is not used up, ascorbate is converted to the more acidic dehydroascorbate.
There is plenty of published literature available online, and it suggests that dehydroascorbate is not the end of the story, especially in alkaline solution. Also, at pH of 8 it doesn't matter much whether some acid has pKa of 1 or 5, it will be fully protonized anyway. The question remains how many protons are produced or consumed in the various redox reactions of Ascorbic Acid and how many protons the resulting compounds will let go at pH around 8.
A pH measurement before and after development sounds easier ...
Trying to be the best of whatever I am, even if what I am is no good.