HPLC Separation of Phthalic Acids using Hydrogen Bonding on Zodiac HST HB Column

Phthalic acid, isophthalic acid, and terephthalic acid are structural isomers that can be challenging to separate using traditional reversed-phase HPLC due to their similar polarity and structure. Moreover, methods involving high concentrations of organic solvents often lead to dewetting issues in many reversed-phase columns.

The Zodiac HST HB column offers a reliable alternative by utilizing hydrogen-bonding interactions under anhydrous conditions. In this method, the separation of phthalic acid isomers was achieved using pure acetonitrile (ACN). Retention times were further optimized by adjusting the ratio of methanol (MeOH) in the mobile phase. The inclusion of formic acid and ammonium formate makes the method LC/MS-compatible.

Detection can be performed using UV at 270 nm, ensuring sensitive and selective analysis of all three isomers.