Determination of phenolic substances in plant materials by capillary electrophoresis and liquid chromatography

A simple, sensitive and fast capillary electrophoretic method was optimized for the identification and determination of allelopathic phenolic compounds (vanillin, caffeic, 4-hydroxybenzoic, ferulic, salicylic, protocatechuic and 4-coumaric acids) in plant materials. Separation in an uncoated silica capillary (Supelco Select-FS75, effective length 22 cm, total length 31 cm, 75 mum I.D., 363 mum O.D.) was performed at 6 kV in 20 mmol.l(-1) boric acid and 60 mmol.l(-1) Na2HPO4 buffer (pH 8.75). The method was applied to the determination of vanillin, 4-hydroxybenzoic and protocatechuic acids in Ranunculus bulbosus, Veronica chamaedrys and Sanguisorba minor and in barley seeds. The results were in good agreement with those obtained by liquid chromatography.