Quantitative Determination of Reducing Sugars and a Sugar Acid by Hydroxamic Acid Formation F. CASTANO U.S. Army Area Medical laboratory,
RUSSELL HlLF and FRANK Chemistry Division, Sixth
b The quantitative aspects of the reaction between hydroxamic acid derivatives of sugar acids and ferric chloride have been studied. Sugar acids were determined by direct hydroxamic acid formation. Reducing sugars were determined by preparation of the hydroxamic acid after cyanohydrin formation. From the results reported, these reactions should b e applicable as a quantitative procedure for the determination of a reducing sugar and a sugar acid, either singly or in a mixture.
A
carboxylic acid derivative will react with alkaline hydroxylamine to form a hydroxamic acid (9). The subsequent reaction of the hydroxamic acid formed with ferric ion has been used in the determination of various lactones and esters (1-3, 6). Recently, Goddu, LeBlanc, and Kright (5) investigated the reaction variables involved, and established conditions under which lactones or anhydrides could be selectively determined in the presence of esters. These reactions suggested a procedure for the measurement of sugar acids. Under proper conditions, a n acid derivative could be prepared and made to react with hydroxylamine, and the resulting hydroxamic acid could be determined by use of ferric ion. For reducing sugars, an acid could be produced after formation of the cyanohydrin via the classical Kiliani reaction, which has been shown to be quantitative (4, 7 ,
