Determination of ascorbate in urine
Ascorbic acid appears in urine with high food intake. As a strong reducing agent, it can affect the determination of some analytes in urine, especially those that use hydrogen peroxide in reactions. It is directly reduced by ascorbic acid. It also rapidly decomposes diazonium salts used for azo-coupling reactions.
The principle of ascorbic acid detection uses phosphomolybdic acid, which is an acid ascorbic reduced to molybdenum blue. The reaction is not specific for ascorbic acid alone, other substances with strong reducing effects react similarly.