Dual-Mode Separation of Diacid Compounds Using Hydrophobic and Ion-Exchange Mechanisms

The Zodiac HST B column combines hydrophobic reversed-phase and ion-exchange mechanisms to separate diacids such as fumaric, benzoic, phthalic, naphthoic, and maleic acids. Adjusting the acetonitrile content in the mobile phase reverses the peak order of naphthoic and maleic acids. The method uses a mobile phase of water, acetonitrile (MeCN), and trifluoroacetic acid (TFA) with UV detection at 250 nm for precise separation.