A STUDY OF THE COLORIMETRIC ASSAY OF URINARY 17-KETOSTEROIDS¹1

Abstract

AT present two technics based on the Zimmermann (1935, 1936) color reaction are widely used for the determination of urinary 17- ketosteroids. In the procedure of Callow (1938) absolute alcohol is used as the solvent for the steroid solution, for the 2 per cent mdinitrobenzene and for the 2.5 N potassium hydroxide. Holtorff and Koch (1940) used 95 per cent alcohol for the solutions of steroid and m-dinitrobenzene but an aqueous solution of 5 N potassium hydroxide. The latter workers considered that a 5 N solution of alkali gave optimal results. Since no direct comparisons of the results obtained by these two methods have been made, it was thought advisable to investigate the accuracy of each method and to determine, as far as possible, the reasons for any discrepancies noted. Application of the colorimetric assay to crude extracts of urine meets with two difficulties, a) the presence of colored substances which bsorbin the green region and b) the presence of chromogens other than 17-ketosteroids.