A screening procedure was developed for the detection of 49 corticosteroids
in topical pharmaceutical products. These products were analyzed by revers
ed-phase HPLC using two gradient systems: a linear gradient of 18-82% aceto
nitrile over 12 min and a linear gradient of 38-88% methanol over 12 min. A
lthough all corticosteroids were not resolved during a single 12-min gradie
nt analysis, a peak retention time from a sample analysis was usually suffi
cient to limit an unknown to 1-3 probable corticosteroids. Steroids unresol
ved with the first gradient system were resolved with the second one, with
the exception of three steroid pairs.
Assignments based on retention times were supported by spectra provided by
a rapid scanning ultraviolet detector. Two extraction procedures were devel
oped to isolate corticosteroids from both water-soluble and lipid-soluble s
ample components. When applied to a variety of topical formulations, the tw
o extraction methods eliminated most of the sample excipients, recovered co
rticosteroids in high yield, and allowed for detection to a level of 0.001%
of the sample.