Efficiency of the new sub-2 μm core-shell (Kinetex™) column in practice, applied for small and large molecule separation.

At present sub-2 μm packed columns are very popular to accomplish rapid and efficient separations. Applying particles with shortened diffusion path to improve the efficiency of separation performs higher efficiency than it is possible with the totally porous particles having the same size. The advantages of sub-2 μm particles and shell particles are combined in the new Kinetex 1.7 μm particles. In this study a systematical evaluation of the efficiency and achievable analysis time obtained with 5 cm long narrow bore column packed with sub-2 μm core-shell particles (1.25 μm core diameter and 0.23 μm porous silica layer), and other type very efficient columns is presented. The efficiency of separation was investigated also for small pharmaceutical and large molecules (proteins). Van Deemter, Knox and kinetic plots are calculated. The results obtained with low molecular weight polar neutral analytes (272 g/mol, 875 g/mol), with a polypeptide (4.1 kDa) and with different sized proteins (18.8 kDa, 38.9 kDa and 66.3 kDa) are presented in this study. Moreover, particle size distribution, and average pore size (low-temperature nitrogen adsorption, LTNA) of the new very fine core-shell particles were investigated. According to this study, increased flow rates can be applied on sub-2 μm core-shell columns to accomplish very fast separations without significant loss in efficiency. The new sub-2 μm shell particles offer very high efficiency both for small and large molecule separation.