FACTORS AFFECTING COLORIMETRIC URINARY 17-KETOSTEROID DETERMINATIONS1

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Abstract
Four different procedures for the colorimetric detn. of 17-kctosteroids (17-KS) were applied to the same neutral fraction of urine extract. Each procedure gave a different value for the 17-KS content of this extract. The lowest values were found with procedures employing either conc. alc., conc. KOH, or both. The extract always reacted at a faster initial rate than the androsterone reference standard, and in conc. reaction mixtures these 2 reached constant color after a given time. Hence, readings made before this plateau gave higher 17-KS values. Except in conc. reaction mixtures 2 crystalline 17-KS did not reach equivalent color intensities even after long times. Hence, the low value obtained in conc. mixtures are probably more accurate. A procedure employing 5N aqueous KOH (Holtorff and Koch) gave almost the same 17-KS values as a procedure carried out entirely in abs. alc. if 13/4 hrs. was allowed for color development. The aq. KOH procedure is preferred as it is less difficult and has a smaller error.