HPLC Separation of Dihydroxybenzoic Acid on Zodiac HST RP Column

The separation of hydrophilic isomers is particularly challenging when using a single retention mechanism such as reversed-phase chromatography, as isomers often exhibit nearly identical hydrophobic characteristics. However, in mixed-mode chromatography, subtle differences in both hydrophobicity and ionic properties can be exploited for effective resolution. Using the Zodiac HST RP column, isomers of dihydroxybenzoic acid were successfully separated with excellent selectivity and peak shape. This approach is also applicable to the analysis of other hydrophilic acidic compounds as well as hydrophobic basic analytes, offering a versatile solution for complex separations.