A new and fast high-performance liquid chromatography (HPLC) method using fused-core column for separation of rutin, troxerutin, diosmin, and hesperidin has been developed and used for determination of these flavonoids in food supplements. Efficient separation of flavonoids and internal standard methylparaben was achieved on the fused-core column Ascentis Express RP-Amide (100 x 3.0 mm), particle size 2.7 mu m, with mobile phase acetonitrile/water solution of acetic acid pH 3 (30:70, v/v) at a flow rate of 1.0 mL min(-1) and at temperature 50 A degrees C.
The detection wavelengths were set at 283 nm for hesperidin and at 255 nm for rutin, troxerutin, diosmin, and internal standard methylparaben. Under the optimal chromatographic conditions, good linearity with correlation coefficients in the range (r = 0.9991-0.9998; n = 7) for all flavonoids was achieved.
Commercial samples of food supplements were extracted with 100 % dimethyl sulfoxide using ultrasound bath for 10 min and then diluted to methanol. A 5-mu L sample volume of the filtered solution was directly injected into the HPLC system.
Accuracy of the method defined as a mean recovery of flavonoids from food supplement matrix was in the range 96.2-104.4 % for all flavonoids. The intraday method precision was satisfactory, and relative standard deviations of sample analysis including preparation and determination of different food supplements were in the range 0.5-3.5 % for all flavonoids.
The developed method has shown high sample throughput during sample preparation process, modern separation approach, and short time (5 min) of analysis.