| 摘要 |
The powder for chromatographic separations is used in the separating zone of chromatographs. It essentially contains a multiplicity of separate porous macroparticles, each of which has a mean diameter of 0.5 to 500 mu m. The powder has a bimodal pore size distribution, the mean pore size for each distribution mode being such that the straight-line portions of the molecular weight calibration curve for each pore size in the bimodal distribution essentially do not intersect. Each distribution mode has a pore volume which is such that these straight-line portions run essentially parallel. At the same time, the mean pore sizes of the components of the bimodal distribution are separated by approximately an order of magnitude. The component of the bimodal distribution having the smaller mean pore size accounts for 30 to 60% of the total pore volume and the component of the bimodal distribution having the larger mean pore size accounts for 70 to 40% of it. The macroparticles are superficially porous and have an impermeable core. They have an envelope composed of a multiplicity of identical single layers made up of colloidal microparticles which touch one another and surround the core and which have a diameter of 0.005 to 1.0 mu m. The macroparticles have a diameter of 5 to 500 mu m and are composed mainly of silicon dioxide. <IMAGE> |
