Preparative chromatography apparatus

B. Apparatus (See Chromatography, Appendix IIA.) Assemble a suitable apparatus for ascending thin-layer chromatography. Prepare a slurry of chromatographic silica gel containing about 13% of calcium sulfate (1 g to each 2 mL of water) as the binder, apply a uniformly thin layer to glass plates of convenient size, dry in air for 10 min, and activate by drying at 100° for 1 h. Store the cool plates in a clean, dry place until ready for use. 

The most common column system used in preparative chromatography is the axial flow cylindrical column and consequently this type of column will be considered first and in some detail. Radial flow columns, and simulated moving bed columns are also used very effectively in preparative chromatography, but these systems constitute very special and expensive apparatus. In addition, initial work with traditional columns will need to be carried out to evaluate and justify the necessary expense that is involved with these more sophisticated type of preparatiye separation systems. 

Preparative Chiral Chromatography The Loading Capacity of a Column The Maximum Sample Volume Sample Volume Overload Sample Mass Overload Preparative Chromatography Apparatus Solvent Reservoirs Pumps... 

Conway, W.D. Countercurrent Chromatography Apparatus, Theory, and Applications-, VCH New York, 1990. Hostettmann, K. Hostettmann, M. Marston, A. Preparative Chromatography Techniques Applications in Natural Product Isolation , Springer-Verlag Berlin, 1986. 

Synthetic chiral adsorbents are usually prepared by tethering a chiral molecule to a silica surface. The attachment to the silica is through alkylsiloxy bonds. A study which demonstrates the technique reports the resolution of a number of aromatic compoimds on a 1- to 8-g scale. The adsorbent is a silica that has been derivatized with a chiral reagent. Specifically, hydroxyl groups on the silica surface are covalently boimd to a derivative of f -phenylglycine. A medium-pressure chromatography apparatus is used. The racemic mixture is passed through the column, and, when resolution is successful, the separated enantiomers are isolated as completely resolved fiactions. Scheme 2.5 shows some other examples of chiral stationary phases. 

The PMMA-Phe synthesis, characterization, film preparation, apparatus and experimental scheme are described elsewhere (H) Briefly, the PMMA chains, copolymerized from MMA and Phe-labelled monomers, were characterized via gel permeation chromatography (GPC) M = 411,000, M = 197,000 and M M - 2.08. UV-absoifption measurementsnindicated that ca. I % of all monomer units were Phe-labelled. The sample was dissolved in toluene and was spin-coated onto 1-inch diameter quartz disks. Then, the films (ca. 1 /zm thick) were annealed at 160 C for 60 minutes under vacuum. 

---