Normal-phase high-performance liquid chromatography of volatile compounds Selectivity and mobile phase effects on polar bonded silica

Abstract

Liquid chromatographic retention data of various volatile alcohols, phenols, ethers, aldehydes, ketones, esters, nitriles, isothiocyanates, and heterocyclic compounds were measured on diol-, cyano- and amino-bonded silica columns. The mobile phase was pentane-diethyl ether in varying compositions. The Snyder theory was applied to retention of polycyclic aromatic hydrocarbons and to selected other compounds. The role of diethyl ether in the retention process was examined. Restricted-access delocalization was observed on all three bonded phases, and was pronounced on diol and amino silica. Secondary solvent effects were important for most compounds, indicating differences in specific solvent-solute interactions between adsorbed and non-adsorbed mobile phase. Principal component analysis was performed on a large set of retention data. Esters and ethers showed clear affinity for diol silica, while alcohols and phenols were preferentially retained on amino silica.