Determination of oxalic acid in herbal medicines by semi-micro hydrophilic interaction liquid chromatography coupled with electrochemical detection.

In this study, the determination of oxalic acid in herbal medicines was performed by using a hydrophilic interaction liquid chromatography coupled with electrochemical detection (HILIC-ECD) method. A semi-micro column packed with amide-silica particles and an acetonitrile-30 mM phosphate buffer (pH 6.8) mixture (65:35, v/v) were used as the stationary and mobile phases, respectively, in the HILIC-ECD.