The presented work describes the development and validation of a rapid UHPLC-UV method using a core-shell particle column with a pentafluorophenyl stationary phase for the separation and quantitative analysis of the six anthocyanins in acai berry and dry blueberry extracts. The anthocyanins (cyanidin-3-glucoside, cyanidin-3-rutenoside, delphinidin-3-galactoside, delphinidin-3-glucoside, delphinidin-3-rutenoside, and peonidin-3-glucoside) were separated and analyzed in 5min. The chromatographic separation was performed on a Kinetex PFP (150×2.1mm) core-shell column with a particle size of 1.7μm at a temperature of 50°C. Acetonitrile was used as mobile phase B and 5% formic acid, filtrated through a 0.22μm filter, as mobile phase A. They were delivered at a flow rate of 0.55mLmin-1 according to the elution gradient program. The detection wavelength was set at 520nm. A solid-liquid extraction with a solution of methanol and a 5% water solution of formic acid (25+75v/v) using an ultrasonic bath was chosen for the preparation of the available commercial samples of food supplements with a content of acai berry extract and blueberry extract. Under optimal chromatographic conditions, the method was validated. Recoveries for all analyzed anthocyanins were 97.8-102.6% and the relative standard deviation ranged from 0.4% to 3.0% for within-day and from 0.6% to 3.1% for between-day repeatability. The limits of detection were in the range of 0.11-0.14μgmL-1.

The Department of Analytical Chemistry Faculty of Pharmacy Charles University Heyrovského 1203 Hradec Králové 500 05 Czech Republic

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Poor chemical and microbiological quality of the commercial milk thistle-based dietary supplements may account for their reported unsatisfactory and non-reproducible clinical outcomes