Development of Monolithic Capillary Chiral Columns Based on Tris(3,5-dimethyl phenyl carbamate) Cellulose Stationary Phase for Micro-HPLC

ECHEVARRIA, ROMINA N.; PADRO JUAN MANUEL; KEUNCHKARIAN, SONIA; CASTELLS, CECILIA B.; RETA, M.

San Francisco, CA

Simposio; 44th International Symposium on High Performance Liquid Phase Separations and Related Techniques, San Francisco, CA, USA.; 2016

Monolithic separation columns offer significant advantages for high-performance liquid chromatography (HPLC) in terms of peak efficiency and analysis time [1]. Monolithic columns based on organic polymers present advantages over the siliceous ones, such as simpler and faster preparation, easy surface derivatization, wider pH stability and better biocompatibility [2]. Additionally, since it is a miniaturized separation technique requires low solvent consumption and small sample volumes with the consequent environmental safety and easy coupling to mass spectrometry [3].Polysaccharides, especially cellulose and amylose, are some of the most abundant optically active polymers on the earth [4]. Carbamate derivatives of cellulose and amylose have been recognized as the most useful ones for both analytical and preparative separations for a wide range of chiral compounds [5,6].In this work, monolithic capillary columns were prepared by in situ polymerization of a mixture of 2-hydroxyethyl methacrylate (HEMA) and ethylene dimethacrylate (EDMA), with different porogenic solvent mixtures (cyclohexanol and 1-dodecanol) and lauryl peroxide (LPO) as polymerization initiator. Prior to polymerization, surface modification of the inner wall of the fused-silica capillary (400 µm i.d) was performed with 3-(trimethoxysilyl)propyl methacrylate. The columns obtained showed good permeability (Bo ̴ 3 x 10-14 m2) and mechanical stability. The beds also were characterized by Scanning Electron Microscopy (SEM), Mercury Intrusion Porosimetry (MIP) and Adsorption Isotherms (BET) from which we observed monoliths with homogeneous morphology, packed orderly with the presence of macro and mesopores characteristic of these structures and with high surface area.These capillary monolithic columns were modified by physical adsorption (coating) of tris (3,5-dimethylphenyl carbamate) cellulose (synthesized in our laboratory) for enantioseparation by microHPLC of pharmacological and environmental compounds. Different physical and chemical effects of the polysaccharide coating on the performance and chromatographic selectivity were studied.[1] B. Chankvetadze, T. Ikai, C. Yamamoto, Y. Okamoto, (2004) J. Chromatogr. A, 1042, 55-60.[2] E.J. Carrasco-Correa, G. Ramis-Ramos, J.M.Herrero-Martínez, M. Lämmerhofer, (2014) J. Chromatogr. A, 1367, 123-130.[3] X. Dong, R. Wu, J. Dong, M. Wu, Y. Zhu, H. Zou, (2008) J. Chromatogr. B, 875, 317-322.[4] J. Shen, S. Liu, P. Li, X. Shen, Y. Okamoto, (2012) J. Chromatogr. A, 1246, 137-144.[5] Y. Okamoto, E. Yashima, (1998) Angew. Chem. Int. Ed. Engl., 37,1021-1043.[6] E. Yashima , C. Okamoto, Y. Okamoto, (1998), Synlett 344.