Low recovery of ascorbyl-palmitate

[CSV]

I'm trying to set up an assay method targeting ascorbyl-palmitate in a complex pharmaceutical formulation. I have succeded in getting baseline separation on a CN column, but have very poor and varying recoveries.
The product has been dissolved in both pure THF and THF:H2SO4(0.02%) 50:50, but the recovery is equally poor. All extraction solvents have been degassed by sonication. I suspect that my analyte is rapidly oxidized, presumably catalyzed by something in the product matrix, and is not sure how to prevent it!

Has anyone encountered the same problem or have any idea of how to adress this problem!

Thanks

[HW Mueller]

It is more likely that you are hydrolyzing the ester, after that it could, of course, oxidize. I don´t remember any particular propensity of this ester to oxidize (that´s why I always wondered why it is used as antioxidant, maybe the antiox property is actually due to Asc that formed). For instance, it can not produce radicals as seen in ESR with Asc (at pH 7).

I would keep THF and acid away from it and run it on ODS.
(Don´t remember exactly just what we did with it)