Quantitative determination of phenolic diterpenes in rosemary extracts. Aspects of accurate quantification.

Practical challenges related to accurate quantification of carnosic acid (CA), carnosol (CAR) and other phenolic diterpenes in extracts of rosemary leaves (Rosmarinus officinalis L.) are presented and discussed. Primary standard material of CA is isolated from rosemary extracts by preparative chromatography with a purity of 98% or higher.