HPLC Separation of Benzalkonium Chloride BCT 8358 on Zodiac HST RP Column

Benzalkonium chloride (BTC) is a mixture of alkylbenzyldimethylammonium chlorides with various even-numbered alkyl chain lengths and is commonly used as a surfactant. In conventional reversed-phase chromatography, hydrophobic quaternary amines like BTC often exhibit poor peak shapes due to interactions between the quaternary ammonium groups and residual silanol sites on the silica surface. The Zodiac HST RP column, a reversed-phase anion-exchange column with embedded basic functional groups, effectively shields silanol interactions, resulting in sharp, symmetrical peaks for hydrophobic amines—quaternary, tertiary, secondary, and primary.

For optimal performance, analytes must possess sufficient hydrophobicity to overcome the repulsive forces from the stationary phase. BTC can be detected using ELSD or UV, and the Zodiac HST RP column also retains acidic counter-ions associated with quaternary amines. This allows for simultaneous analysis of both hydrophobic basic and hydrophilic acidic compounds in a single run.