Use of an Internal Standard to Assay 6 β-Hydroxycortisol in Urine

Abstract
Currently 6 β-hydroxycortisol is assayed by radio-immunoassay or high performance liquid chromatography techniques. We have developed an HPLC method, utilizing gradient elution and an internal standard {a 4-pregnene-tetrol-3-one}. In this way, accuracy and sensitivity of the assay were greatly improved and allowed the application of this modified method for monitoring the time-course of hepatic microsomal enzyme activity.