FLOW-INJECTION CHEMILUMINOMETRIC DETERMINATION OF STEROIDS

A rapid, accurate, precise and fully automated flow-injection method is described for the determination of 0.02-0.50 mu g ml(-1) cortisone, 0.02-1.00 mu g ml(-1) hydrocortisone and 0.20-5.00 mu g ml(-1) dexamethasone in aqueous solutions and of 1.0-20.0 mu g ml(-1) prednisolone, methylprednisolone, progesterone, corticosterone and testosterone and 2.0-20.0 mu g ml(-1) betamethasone in 20% (v/v) acetonitrile solutions. The method is based on the sensitizing effect of each steroid on the chemiluminogenic cerium(IV)-sulphite reaction. Limits of detection are in the ranges 0.013-0.019 and 0.05-4.00 mu g ml(-1) for aqueous and acetonitrile solutions, respectively. Common excipients do not interfere greatly and the mean recovery of steroids from commercial formulations was 102.6% (range 94.2-109.0%). The method allows the measurement of up to 100 samples per hour and can be used for content uniformity tests and the results were in good agreement with the official method for commercial formulations with a relative error < 4%.