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Characterization of dehydroascorbic acid solutions by liquid chromatography/mass spectrometry
P Pastore1, T Rizzetto, O Curcuruto
1Department of Inorganic, Metallorganic and Analytical Chemistry, University of Padua, via Marzolo 1, 35131 Padua, Italy. paolo.pastore@unipd.it
Rapid Communications in Mass Spectrometry : RCM
|December 18, 2001
Summary
Dehydroascorbic acid (DA) solutions contain dimeric forms and a hydrated hemiketal. Light exposure causes dimers to degrade into other forms, while ascorbic acid (AA) solutions only form the hemiketal.
Area of Science:
- Analytical Chemistry
- Biochemistry
- Food Chemistry
Background:
- Dehydroascorbic acid (DA) is an oxidation product of ascorbic acid (AA).
- Understanding DA's solution composition is crucial for its applications and stability studies.
- Previous analyses lacked detailed characterization of DA species in solution.
Purpose of the Study:
- To elucidate the composition of dehydroascorbic acid (DA) solutions.
- To identify DA's various forms and decomposition products.
- To compare DA formation from ascorbic acid (AA) under light exposure.
Main Methods:
- Liquid chromatography/mass spectrometry (LC/MS).
- Liquid chromatography/tandem mass spectrometry (LC/MS/MS).
- Analysis of dehydroascorbic acid (DA) and ascorbic acid (AA) solutions at pH 2.
Main Results:
- Freshly prepared DA solutions primarily contain dimeric forms and the hydrated bicyclic hemiketal.
- Light exposure degrades DA dimers into other dehydrated dimers and monomers.
- Ascorbic acid (AA) solutions under light predominantly form the hemiketal DA, with no observed dimers.
Conclusions:
- The hydrated bicyclic form is the natural product of AA oxidation to DA.
- LC/MS and LC/MS/MS are essential for identifying DA species, surpassing LC/UV.
- DA stability and speciation are significantly influenced by light and solution conditions.