Over the last ten years, the technological progress has led to the development of stationary phases on ever smaller silica particles and instuments (UHPLC/UHPSFC) with a reduced extra-column volume able to reach very high pressure. These innovations allow to obtain higher efficiencies, resolutions and permit to reduce the analysis time and the eluent consumption. For these reasons also chiral stationary phases (CSPs) are moving to sub-2µm particles diameter. This talk concerns the development of two different sub-2µm CSPs based on the WhelkO-1 [1] and on the teicoplanin macrocyclic selectors[2]. The first selector has been covalently bonded on fully porous 1.8 µm Kromasil and the second one on totally porous and monodispersed 1.9 µm Titan silica particles (TEICO-Titan). Both CSPs were packed in columns with an internal diameter of 4.6 mm and different lengths, from 10 cm down to 1 cm, the latter geometry permitting very short analysis time. The different columns containing the two CSPs were analyzed under several elution conditions to obtain a complete thermodynamic and kinetic characterization. The UHPLC columns packed with the brush-type WhelkO-1-CSP were evaluated using normal phase and supercritical fluid eluents. Kinetic performances were estimated using trans-stilbene oxide as a probe, and resulted in efficiencies up to 250’000 plates/m at the optimal flow-rate of 2.0 mL/min under normal phase elution conditions. To evaluate the thermodynamic performances a large library screening[3] was performed using carbon dioxide based eluents under sub-critical fluid conditions: in one working day, 81 out of 129 randomly collected racemates were resolved under identical eluting conditions using a 9 min methanol in CO2 gradient with 0.1% TFA or 0.1% NH3 added for acidic and basic compounds, respectively. The TEICO-Titan 1.9 µm CSP showed a broad field of application in different environments (reversed phase, polar organic mode, sub-critical fluid and normal phase). The thermodynamic performances of the new TEICO-Titan 1.9 µm have been evaluated with several N-protected amino acids, aryloxy acids, pharmaceutical compounds, sulfoxides and phosphine oxides. This CSP frequently showed high enantio-selectivity values: these resulted in large resolutions on the 10 cm long column (Rs up to 10.7 with Fmoc-D,L-Ala) and allowed the use of 2 cm and even 1 cm long columns in many cases, providing a considerable reduction of the analysis time maintaining a baseline enantiomeric separation. References [1] D. Kotoni, A. Ciogli, C. Molinaro, I. D’Acquarica, J. Kocergin, T. Szczerb, H. Ritchie, C. Villani, F. Gasparrini, Anal. Chem., 84 (2012), 6805 [2] Berthod A., Chen X., Kullman J.P., Armstrong D.W., Gasparrini F., D’Acquarica I., Villani C., Carotti A., Anal. Chem. 72 (2000) 1767-1780; [3] L. Sciascera, O. Ismail, A. Ciogli, D. Kotoni, A. Cavazzini, L. Botta, T. Szczerba, J. Kocergin, C. Villani, F. Gasparrini, JCA, 1383 (2015) 160–168
Development, characterization and applications of new sub-2micron totally porous WhelkO-1 brush-type and macrocyclic chiral stationary phases
Omar H. Ismail
2015
Abstract
Over the last ten years, the technological progress has led to the development of stationary phases on ever smaller silica particles and instuments (UHPLC/UHPSFC) with a reduced extra-column volume able to reach very high pressure. These innovations allow to obtain higher efficiencies, resolutions and permit to reduce the analysis time and the eluent consumption. For these reasons also chiral stationary phases (CSPs) are moving to sub-2µm particles diameter. This talk concerns the development of two different sub-2µm CSPs based on the WhelkO-1 [1] and on the teicoplanin macrocyclic selectors[2]. The first selector has been covalently bonded on fully porous 1.8 µm Kromasil and the second one on totally porous and monodispersed 1.9 µm Titan silica particles (TEICO-Titan). Both CSPs were packed in columns with an internal diameter of 4.6 mm and different lengths, from 10 cm down to 1 cm, the latter geometry permitting very short analysis time. The different columns containing the two CSPs were analyzed under several elution conditions to obtain a complete thermodynamic and kinetic characterization. The UHPLC columns packed with the brush-type WhelkO-1-CSP were evaluated using normal phase and supercritical fluid eluents. Kinetic performances were estimated using trans-stilbene oxide as a probe, and resulted in efficiencies up to 250’000 plates/m at the optimal flow-rate of 2.0 mL/min under normal phase elution conditions. To evaluate the thermodynamic performances a large library screening[3] was performed using carbon dioxide based eluents under sub-critical fluid conditions: in one working day, 81 out of 129 randomly collected racemates were resolved under identical eluting conditions using a 9 min methanol in CO2 gradient with 0.1% TFA or 0.1% NH3 added for acidic and basic compounds, respectively. The TEICO-Titan 1.9 µm CSP showed a broad field of application in different environments (reversed phase, polar organic mode, sub-critical fluid and normal phase). The thermodynamic performances of the new TEICO-Titan 1.9 µm have been evaluated with several N-protected amino acids, aryloxy acids, pharmaceutical compounds, sulfoxides and phosphine oxides. This CSP frequently showed high enantio-selectivity values: these resulted in large resolutions on the 10 cm long column (Rs up to 10.7 with Fmoc-D,L-Ala) and allowed the use of 2 cm and even 1 cm long columns in many cases, providing a considerable reduction of the analysis time maintaining a baseline enantiomeric separation. References [1] D. Kotoni, A. Ciogli, C. Molinaro, I. D’Acquarica, J. Kocergin, T. Szczerb, H. Ritchie, C. Villani, F. Gasparrini, Anal. Chem., 84 (2012), 6805 [2] Berthod A., Chen X., Kullman J.P., Armstrong D.W., Gasparrini F., D’Acquarica I., Villani C., Carotti A., Anal. Chem. 72 (2000) 1767-1780; [3] L. Sciascera, O. Ismail, A. Ciogli, D. Kotoni, A. Cavazzini, L. Botta, T. Szczerba, J. Kocergin, C. Villani, F. Gasparrini, JCA, 1383 (2015) 160–168I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
