The colorimetric determination of streptomycin in clinical preparations, urine, and broth.

The streptomycin molecule contains a number of functional groups which may serve as bases for chemical assay. The Sakaguchi reaction has been used to test for the guanido groups of the molecule (l), and a reaction given by the N-methyl-L-glucosamine moiety (2) of streptomycin has been reported (3). Furthermore, the molecule has a free or potentially free carbonyl group (4) and marked reducing properties. Any of these groups can be used as a basis for assay purposes on highly purified material, but these reactions are not sufficiently specific for samples of lower potency or biological fluids. A means of assay was suggested by the observation that streptomycin on being heated with dilute alkali forms maltol, 2-methyl-3-hydroxy-rpyrone (5). Malt01 shows characteristic absorption maxima in the ultraviolet in both acid and alkaline solutions, and reacts with ferric ions to give a purple-red color which is stable in acid solution (6). We have further observed that malt01 reacts with the phenol reagent of Folm and Ciocalteu to give the usual blue color. The calorimetric assay procedure for streptomycin presented in this paper is based on these reactions of maltol.