Quantitative determination of phenol derivatives from Oleum Thymi

The thymol and carvacrol content in Oleum Thymi was determined by densitometry. Phenols were separated on a thin - layer of silica gel using two-step gradient elution. The dependence of measurement time on the amount of phenols was investigated. For comparison, the total phenolic content of the essential oil was also determined by colorimetry, the results indicating that the optimal measurement time at which the following measurements should be performed, is 5 min after the end of heating.