Determination of umckalin in commercial tincture and phytopreparations containing Pelargonium sidoides by HPLC: Comparison of sample preparation procedures

Roots of Pelargonium sidoides D.C. are used for the production of phytomedicines. Current quality control of phytopreparations containing P. sidoides extracts has been made in terms of total phenolics content. In this work we describe the development and validation of an HPLC method for the analysis of P. sidoides tincture and commercial syrup phytopreparations using umckalin (7-hydroxy-5,6-dimethoxycoumarin) as chemical marker. Two sample preparation procedures, liquid–liquid extraction (LLE) and solid-phase extraction (SPE) were also developed and compared. The samples were analyzed by RP-HPLC and the two methods were then validated and compared. The repeatability of the two procedures showed coefficients of variation (CV) of 1.2% for SPE procedure, and 1.3% for LLE. Recovery for both methods was higher than 95.2%. The linearity showed correlation coefficients better than 0.999 for both methods. The detection and quantification limit were 0.0098 and 0.0298 μg mL−1, respectively. The validated procedure was then used for the analysis of tincture and five batches of two commercial phytopreparations containing P. sidoides tincture.