Development of conditions for rapid extraction and
separation of tretinoin and isotretinoin from dermatological
formulations
The desired goal of a method that would allow high throughput
quantification of tretinoin and isotretinoin in dermatological
formulations was to complete an analysis from the formulation
in a total of 30 min or less. The extraction procedure developed
for tretinoin and isotretinoin from dermatological preparations
allowed samples to be available for HPLC analysis in approximately
10 min. Conditions for a rapid and simple HPLC separation
with UV detection were developed using an isocratic elution
with a mobile phase composed of 0.01% trifluoroacetic acid and
acetonitrile (15:85, v/v). These conditions gave well resolved,
sharp peaks for both tretinoin and isotretinoin with retention
times of approximately 11.3 min for tretinoin and 9.6 min for
isotretinoin as shown in Fig. 1. Under these conditions, amounts
of tretinoin and isotretinoin as low as 0.06 g/ml could be readily
detected. With these retention times, sequential analyses could
be completed in less than 20 min. Since these conditions met
our goal for high throughput analysis, validation experiments
were completed to determine if the method could achieve the
reproducibility and accuracy required for analysis of tretinoin
formulations.