ascorbate/dehydroascorbate stability

[Deirdre Fahy]

I am working on assays for ascorbate and dehydroascorbate. I am concerned
about
maximising stability, i.e. maintaining ascorbate in the reduced state and
preventing
irreversible breakdown of dehydroascorbate. My tissue is freeze-dried apple
peel
extracted in 5%TCA. At present, my standards for ascorbate give higher abs.
than
equivalent standards of dehydroascorbate (after reduction). Assay method:
reduction of ferric ion with ascorbate, ferrous ion chelates
bathophenantholine.
I would appreciate any helpful hints.

Thank you

Deirdre Fahy