Cereal Chem 59:69 - 71.  |  VIEW ARTICLE
Determination of Ascorbic Acid in Wheat Flours, Bread Dough Conditioners, and Commercial Vitamin C Tablets by High-Performance Liquid Chromatography.

G. L. Lookhart, S. B. Hall, and K. F. Finney. Copyright 1982 by the American Association of Cereal Chemists, Inc. 

A high-performance liquid chromatography method was developed to determine ascorbic acid (vitamin C) in wheat flours, bread dough conditioners, and commercial vitamin C tablets. Dithiothreotol (0.7mM) stabilized vitamin C without reducing extraction efficiency. Extraction and analysis were complete in less than 30 min. Extraction efficiencies were 73-78% for the flours and 100% for the dough conditioners and vitamin C tablets. Vitamin C contents of dough conditioners were found to be higher than the labeled potency. Over-the-counter vitamin C tablets, stored in capped vials for various periods of time at room temperature, had a shelf life of at least 14 years. The method is over 1,000 times more sensitive than the AOAC method (10 ng vs 50 microgram) and is not adversely affected by some metal ions and basic compounds.