NORMAL-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY OF VOLATILE COMPOUNDS - SELECTIVITY AND MOBILE-PHASE EFFECTS ON POLAR BONDED SILICA

Liquid chromatographic retention data of various volatile alcohols, ph enols, ethers, aldehydes, ketones, esters, nitriles, isothiocyanates, and heterocyclic compounds were measured on diol-, cyano- and amino-bo nded silica columns. The mobile phase was pentane-diethyl ether in var ying compositions. The Snyder theory was applied to retention of polyc yclic aromatic hydrocarbons and to selected other compounds. The role of diethyl ether in the retention process was examined. Restricted-acc ess delocalization was observed on all three bonded phases, and was pr onounced on diol and amino silica. Secondary solvent effects were impo rtant for most compounds, indicating differences in specific solvent-s olute interactions between adsorbed and non-adsorbed mobile phase. Pri ncipal component analysis was performed on a large set of retention da ta. Esters and ethers showed clear affinity for diol silica, while alc ohols and phenols were preferentially retained on amino silica.