Citric Acid → L-Ascorbic Acid

Participants

Reaction Steps

7 grams of the sodium salt of 2,18-phosphomolybdic acid, 4 grams of sodium chlorate, 40 grams of citric acid, and 13.5 grams of trilithium citrate are dissolved in a mixture of 600 ml of methanol and 380 ml of water. A filter paper, for example Type 2668, made by the Schleicher & Schull Company, is impregnated with this solution, which has a pH-value of 3.6, and is dried for 1 hour at 60° C. Pieces measuring 6×6 mm are cut from the test paper prepared in this way, and sealed between a plastic handle and a thin nylon net, according to German Pat. No. 2 118 455. In urines with ascorbic acid in the important decision range of 0-40 mg of ascorbic acid/dl of urine, these test strips give very graduated reaction colors from bright greenish-blue to dark bluish-violet.

Provenance & Evidence