Determination of resveratrol in grains, hulls and leaves of common and tartary buckwheat by HPLC with electrochemical detection at carbon paste electrode

A reverse-phase high-performance liquid chromatographic method for the determination of trans-resveratrol with spectrophotometric detection (306 nm) and amperometric detection at carbon paste electrode (E = + 1,2 V) was developed and tested on real samples of grains, hulls and leaves of six varieties of common buckwheat (Fagopyrum esculentum Möench) and two varieties of tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.). Optimal conditions for the determination of trans-resveratrol were as follows: column Kromasil C-18 (7 μm), 125 × 4 mm; mobile phase acetonitrile: diluted BR buffer pH 7 (50:50, 30:70 for grains and hulls and 20:80 for leaves); flow rate 1 ml min−1. Under these conditions, the limit of detection of trans-resveratrol (LD) was 3.5 × 10−8 mol l−1 (R2 = 0.9986) for electrochemical detection and 3.2 × 10−8 mol l−1 (R2 = 0.9993) for spectrophotometric detection.