High-performance liquid chromatographic columns and stationary phases in supercritical-fluid chromatography

Subcritical fluid chromatography of water soluble nucleobases on various polar stationary phases facilitated with alcohol‐modified CO2 and water as the polar additive

“…Despite their dissimilarity, Geiser et al [5] reported approximately 20 years ago the separation of underivatized fatty acids using water as a modifier in CO 2 . Engelhardt et al [6] showed a year later that the addition of water to CO 2 significantly improved the peak shapes of weak acids and bases on silica-based columns. France et al used a Deltabond octyl column with water saturated CO 2 for the analysis of fatty acids along with di-and tri-glycerides [7].…”

“…Engelhardt et al . 6 showed a year later that the addition of water to CO 2 significantly improved the peak shapes of weak acids and bases on silica‐based columns. France et al used a Deltabond octyl column with water saturated CO 2 for the analysis of fatty acids along with di‐ and tri‐glycerides 7.…”

Supercritical Fluid Chromatographic Separation of Dimethylpolysiloxane Polymer

“…A good way to overcome these problems is to use a saturator column 9,10,11 to add polar modifiers to supercritical CO 2 . For the experiment, water was used as a modifier and a µ-Porasil column was used as a saturator column with system desing similar to that described by Engelhardt et al 9 With this desing, a polar modifier (water) can be added to pressurized CO 2 after the pump, and thus no modifier remains in the pump. Supercritical CO 2 is delivered from the pump to the µ-Porasil column which is saturated with water.…”

“…Several workers [6][7][8] have reported the influence of modifiers on peak shape, selectivity and retention time in capillary and packed-column SFC. A simple and effective way to add modifiers to a supercritical fluid mobile phase is to use a saturator column, 9,10 which is usually a silica column saturated with polar alcohols.…”

Fast Separation Method Development for Supercritical Fluid Chromatography Using an Autoblending Protocol

“…In addition to normal modifiers, some additives such as formic acid, ammonium formate, ammonium acetate and triethylamine are often introduced to the mobile phase to improve peak shape and efficiency in achiral and chiral separations. For example, amines [22] are often added to decrease tailing when basic samples are being analyzed, and water [23][24][25][26] has also been added to change the selectivity. In general, acids were used to elute acidic analytes and bases were used to elute basic analytes.…”