Reactions of biogenic amines with aqueous potassium dichromate. An application to the determination of dopamine.

The reaction of potassium dichromate with a series of phenols, aminophenols, catecholamines, indolealkylamines and metabolites of the latter two was studied. Reaction required the presence of aromatic ortho- or para-dihydroxy or -diamino groups. Potassium dichromate reacted not only with the vicinal hydroxyl groups of catecholamines but also with the 5-hydroxy group and the ring nitrogen in the indolealkylamine series. Reaction occurs immediately upon mixing the reagents; the colored products are insoluble in water and most common organic solvents. 3-O-methylated catecholamines and acids and 5-O-methylated indolealkylamines and acids did not react with dichromate. Physical and chemical data on the products of these reactions suggest lack of reaction with the side chain in the biogenic amines. A method using dichromate oxidation-products to determine dopamine concentrations in urine is presented.