Simultaneous determination of acid carnosic and carnosol in rosemary-containing foods by high-performance liquid chromatography with photodiode array detection (HPLC–PDA)

The research was conducted to develop and validate a simultaneous quantification method for acid carnosic (CA) and carnosol (CAR) in rosemary-containing foods using highperformance liquid chromatography coupled with photodiode array detection (HPLC–PDA), with a simple and fast sample processing procedure. Analytical samples were extracted using a methanol–phosphoric acid mixture (99.5:0.5, v/v) at room temperature for 20 minutes. The chromatographic conditions were as follows: Sunfire C18 column (4.6 mm x 250 mm; 5 µm), mobile phase consisting of 0.1% phosphoric acid – acetonitrile (40:60, v/v), flow rate of 1 mL/min, injection volume of 10 µL, detection at 230 nm. The method was validated according to the Association of Official Analytical Chemists (AOAC) criteria. The results showed that the method had good specificity, and the standard curves of acid carnosic and carnosol were linear in the concentration range of 2.5 – 200 µg/mL. The limits of detection (LOD) for acid carnosic and carnosol were 0.3 µg/mL and 0.25 µg/mL, respectively. The limits of quantification (LOQ) for acid carnosic and carnosol were 1 µg/mL and 0.75 µg/mL, respectively. The recovery rates were in the range of 98.8 – 100.6% (acid carnosic) and 97.5 – 102.2% (carnosol). Repeatability and internal reproducibility met the requirements of AOAC. The method was applied to evaluate the acid carnosic and carnosol levels in 20 food samples collected from the market, such as rosemary leaf powder, dried rosemary leaves, rosemary herbal tea,...