Summary

A direct quantitative thin-layer Chromatographic method for the determination of fluocortolone, fluocortolone caproate and nicotinic acid benzylester in the presence of each other in pharmaceutical preparations is described. The active ingredients were extracted from the preparations with an electronically controlled extraction apparatus within 15 min. Development of thin-layer chromatograms was carried out on silica gel 60 F254 precoated plates. All three active ingredients can be separated on one plate using one solvent system namely diethyl ether — hexane — benzene (75∶25∶1) and determined directly by the remission method using a densitometer. Fluocortolone and fluocortolone caproate were measured at 243 nm and nicotinic acid benzylester at 263 nm. Evaluation of thinlayer chromatograms takes place on-line from the linear calibration curves using an IBM 1800 computer. The described method is suitable for analyses of these substances in pharmaceutical preparations, such as ointments and creams and can be well reproduced with a coefficient of variation between 1.3–3.5% for the three active ingredients.