A supercritical fluid workflow for the quality assessment of herbal drugs and commercial preparations from Rhodiola rosea

INTRODUCTION: Preparations from the Rhodiola rosea are experiencing an increase in popularity: extracts of dried roots and rhizomes are used as adaptogen to treat stress, fatigue, and weakness. To meet high pharmaceutical standards, fast and reliable methods to assess phytochemical variations in respect of quality control are needed. OBJECTIVE: The aim of this study was to extract and quantify seven characteristic secondary metabolites of R. rosea , namely p‐tyrosol (1), rosin (2), rosiridin (3), salidroside (4), rosarin (5), rosavin (6), and tricin‐5‐O‐β‐d‐glucopyranoside (7) in 24 herbal drugs and seven commercial preparations using a newly established supercritical fluid workflow. METHODS: The developed protocol allowed for an exhaustive extraction of compounds 1–7 using 60% carbon dioxide (CO(2)) and 40% methanol. The constituents were analysed on an ultra‐high‐performance supercritical fluid chromatography (UHPSFC) instrument using a charged surface hybrid fluoro‐phenyl (CSH FP) column (3.0 mm × 100 mm, 1.7 μm; mobile phase: CO(2) and methanol). RESULTS: The seven compounds were separated in a remarkably short time (< 3.5 minutes). For their quantitation, good results in terms of selectivity, linearity (R (2) ≥ 0.99), precision (intraday ≤ 3.03%, interday ≤ 5.17%) and accuracy (recovery rates 96.6–102.4%) were achieved using selected ion recording on a Quadrupole Dalton (QDa) mass detector. CONCLUSION: The quantitative analysis of the investigated herbal drugs showed a highly differing metabolite pattern which was also observed in the investigated commercial products. None of the commercial dietary products met the declared content of rosavins and salidroside. The developed and validated protocol offers a novel and reliable method to assess the quantitative composition of Rhodiola herbal drugs and preparations.