Ammonia as a preferred additive in chiral and achiral applications of supercritical fluid chromatography for small, drug-like molecules

Evaluation of stationary phases packed with superficially porous particles for the analysis of pharmaceutical compounds using supercritical fluid chromatography

“…improving the peak shapes of basic drugs, by disrupting the interactions between silanols and basic solutes under SFC conditions [6,51,56]. Therefore, the use of a relatively strong base will likely modify the surface chemistry of the silica, which usually results in improved peak shapes.…”

“…ultra-fast separations using ballistic mobile phase gradients without a significant loss of chromatographic efficiency. Compressed carbon dioxide (CO 2 ) mixed with an organic modifier (typically an alcohol) is the most common mobile phase for SFC and offers a broad range of conditions suitable for separating a wide variety of polar and non-polar compounds [5][6][7][8][9][10][11][12][13]. SFC is considered to be thermodynamically comparable to liquid chromatography (LC), offering complementary selectivity based on stationary phase chemistry, mobile phase (organic solvents and additives), pressure, and column temperature.…”

Use and practice of achiral and chiral supercritical fluid chromatography in pharmaceutical analysis and purification

“…However, their high UV absorption may be a problem in the case of gradient elution when low level impurities must be identified. Alternatively, ammonium hydroxide and ammonia have been recommended in many recent reports , as they have an additional benefit of limited UV baseline drift when gradient elution is employed.…”

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

“…However, this can be difficult to achieve. The selection of proper additives is the key point to the development of separation method for the simultaneous analysis of complex components by SFC [13][14][15]. as of now, in most laboratories, using appropriate mobile phase is the most acceptable and efficient method to yield good separation on a generic column.…”

“…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.…”