Simultaneous Determination of Caffeic Acid and Ferulic Acid in Oral Liquid by RP-HPLC

An HPLC method was established for the simultaneous determination of ferulic acid and caffeic acid in oral liquid.The Shim-pack VP-ODS column(150 mm×4.6 mm,0.3 μm) was used with a mobile phase of acetonitrile-3% acetic acid(11∶89 by volume).The contents of ferulic acid and caffeic acid were detected at a wavelength of 321 nm.The flow rate was 1.0 mL/min and the injection volume was 20 μL.The calibration curve was linear in the range of 0.126-63.0 μg/mL(r=0.999 7) for caffeic acid and 0.120-24.0 μg/mL(r=0.999 9) for ferulic acid.The average recovery(n=3) was 100.7% with RSD 2.11% for caffeic acid and was 99.9% with RSD 2.12% for ferulic acid.The detection limit was 42 ng/mL for caffeic acid and 43 ng/mL for ferulic acid.The average content of the samples was 3.26 μg/mL for caffeic acid and 2.36 μg/mL for ferulic acid.