Teicoplanin Chiral Stationary Phases On 2.0 µm And 2.7 µm Superficially Porous Particles: Chromatographic Evaluation And Comparison With Teicoplanin On 1.9 µm Fully Porous Particles.

For the first time, a new generation of Chiral Stationary Phases (CSPs) for Ultra-High Performance Chromatography (UHPC) was prepared covalently bonding the teicoplanin (TE_A2) selector on Halo 2.0µm and 2.7µm (90Å, 125m2/g) Superficially Porous silica Particles (SPP) [1]. The new CSPs were compared with the already known UHPC-FPP-Titan-Tzwitt 1.9 CSP based on Fully Porous monodispersed silica Particles [2]. Columns with an internal diameter of 4.6 mm and different lengths (20, 50 and 100 mm) were packed with the three CSPs and characterized in terms of permeability, efficiency, retention and enantioselectivity under HILIC conditions. Van Deemter curves, generated using both achiral and chiral analytes, showed excellent results with more than 310000 plates/m at 1.6 mL/min (thiourea, k’= 0.6), and more than 290000 plates/m at 0.9 mL/min (2-(4-chloro-phenoxy)-propionic acid, 1st eluted enantiomer, k’= 0.8) on the SPP-Halo 2.0µm. The kinetic performance limits of the columns were investigated also through different kinetic plots, that proved the superior potential of the SPP-Halo 2.0µm and FPP-Titan 1.9µm compared to the SPP-Halo 2.7µm particles in the majority of the kinetic plots area, especially in the region of the ultra-fast/ultra-high efficiency separations. For several chiral analytes, the columns packed with SPP-Halo 2.0µm and FPP-Titan 1.9µm CSP were superior, in terms of efficiency, to the columns packed with SPP-Halo 2.7µm, proving the validity of the van Deemter analysis. Furthermore, from the thermodynamic point of view, the SPP-Halo 2.0µm have shown the best resolution power, with Rs values significantly higher than those of the SPP-Halo 2.7µm and FPP-Titan 1.9µm. Lastly Ultra-High speed – Ultra-High Performance applications performed on three 5-cm long columns, using chiral probes and different eluent flow-rate (1.0 – 6.0 mL/min) showed very high efficiency values and the FPP-Titan 1.9µm CSP, and again a lower performance for the columns packed with the SPP-Halo 2.7µm CSP. Considering the high resolution values observed, 2-cm long columns were prepared and used to explore Ultra-High speed – Ultra-High Performance separations in the seconds time regime: the enantiomers of Haloxyfop were resolved in only 3 seconds with a resolution Rs = 2 on the column packed with SPP-Halo 2.0µm CSP, using an eluent flow rate of 8.0 mL/min. REFERENCES 1. O.H. Ismail, M. Antonelli, A. Ciogli, G. Sestito, D.S Bell, A. Cavazzini, C. Villani, F. Gasparrini, JCA, in preparation 2. O.H. Ismail, A. Ciogli, C. Villani, M. De Martino, M. Pierini, A. Cavazzini, D.S. Bell, F. Gasparrini, JCA, 1427 (2016), 55–68