An Improved Method for the Measurement of Urinary 17-ketosteroids of Small Laboratory Animals.

formula (1, 2) has circumvented this problem to some extent. However, the amount and type of interfering chromogen in urine is not a constant factor, so that the routine use of the correction formula often leads to unreliable results. Recently Sheath (3) reported that the addition of formalin to urine prior to hot-acid hydrolysis greatly reduced the formation of nonsteroidal chromogens. Also, the partitioning of the Zimmerman color and nonspecific chromogens between methylene chloride and aqueous ethanol prior to colorimetry has been described (4-6). The combination of these two technics in our laboratory has led to an assay of urinary 17-ketosteroids of small laboratory animals with a degree of reliability and accuracy not obtainable with either technic alone.