Evaluation and comparison of various separation techniques for the analysis of closely-related compounds of pharmaceutical interest

Maximizing kinetic performance in supercritical fluid chromatography using state-of-the-art instruments

“…The success of highly efficient, fast separations depends on both the intrinsic column efficiency and on preserving this efficiency by minimizing the instrument induced extra-column band spreading [17,18]. Extra-column band spreading affects the measured performance of columns packed with small particles, especially for columns with an internal diameter smaller than the standard of 4.6 mm [19][20][21].…”

“…packed with very fine particles (e.g. 1.7 m) for highly efficient SFC separations [16,17]. Therefore, it was of great interest to evaluate the contribution of current instrumentations to the separation performance and find out the optimal column dimension.…”

“…To overcome this weakness, two of the most important providers of chromatographic instrumentation (Agilent and Waters) developed a new generation of analytical SFC instruments, allowing comparable sensitivity and robustness to that of HPLC [10][11][12]. In parallel, polar stationary phases packed with core-shell sub-3 m particles [13] or fully porous sub-2 m particles [14][15][16][17] compatible with supercritical conditions have been commercialized, enabling a user to achieve kinetic performance comparable and sometimes even better than in LC.…”

Possibilities of retention modeling and computer assisted method development in supercritical fluid chromatography

“…Also in HILIC, a multi-modal retention mechanism exists, combining partitioning, adsorption through H-bonding and electrostatic and ionic interactions [10], and non-linear retention models have been reported [11][12][13]. Therefore, the non-linear retention models that have proven to be successful in HILIC retention modeling could also be of interest for the SFC retention modeling: ln(k) = ln(k w ) + S 1 + S 2 ln( ) (1) ln(k) = ln(k w ) + S 1 + S 2 2 (2) ln(k) = ln(k w ) + 2 · ln(1 + S 2 ) − S 1 1 + S 2 (3) where is the fraction of water, k w the extrapolated value of k for = 0 (i.e., pure CO 2 ), S 1 the slope and S 2 the curvature coefficient [14].…”

“…Supercritical fluid chromatography (SFC) is gaining in importance as a chromatographic technique, to analyze a wide range of compounds from relatively hydrophilic to highly lipophilic [1][2][3][4]. In SFC, the retention mechanism is multi-modal, combining different interaction mechanisms, and highly dependent on the nature of the stationary phase and the type of organic modifier [5,6].…”