Column slurry preparation

Glass chromatography column 400 x 15-mm i.d. with a stopcock Column preparation A silica gel column is prepared by packing a slurry of silica gel (10 g) in n-hexane-acetone (9 1, v/v) into a glass chromatography column. About a 1-cm layer of anhydrous sodium sulfate is placed above and below the... 

Silica gel column cleanup. Prepare a silica gel column by placing a glass-wool plug in the bottom of a glass chromatography column. Slurry 18g of silica gel with hexane-ethyl acetate (4 1, v/v) and pour the slurry into the column. Rinse the walls of the column with hexane-ethyl acetate, and add approximately 2 g of sodium sulfate to the top of the silica gel column. Drain the solvent to the top of the sodium sulfate layer. 

Retention times of molecules separated over mesoporous silica are much longer than those obtained by using commercially available silica, this is due to the increased surface area of mesoporous silica, which in turn increases molecular capacity factors. Differences between capacity factors are also enhanced Thus, molecules which elute with similar retention times on commercial HPLC columns, with overlapping peaks, can be successfully separated by using HPLC columns slurry packed with mesoporous silica. The long retention times are somewhat of a drawback in that large amounts of solvent must be used and the peak shapes of molecules with long retention times can be broad. Mesoporous silica may not be ideal for routine analytical separations but provides an excellent and cost-effective preparative separation medium. 

The Amberlyst (NH4+) resin column is prepared as follows Amberlyst 15 (H+) (56 g, 100 mL dry, Rohm Haas Co.) is suspended in an open beaker containing methanol (100 mL). [Caution the slurry exotherms to ca. 40CC without external cooling, and expands to ca. 1.5 times its initial volume.] The slurry is poured into a 2.5 x 30-cm column and is eluted with 1 M methanolic ammonia (ca. 1 L) until a sample of the eluent diluted 1 1 with water is basic. The resin is then eluted with methanol (ca. 0.5 L) until a sample of the eluent diluted 1 1 with water is neutral. Once prepared, the column can be reused multiple times. 

The preferred method for packing silica gel and alumina columns is the slurry method, whereby a slurry of the adsorbent and the first eluting solvent is made and poured into the column. When nothing is known about the mixture being separated, the column is prepared in petroleum ether, the least polar of the eluting solvents. 

A size-exclusion column is prepared by pouring 50 ml of Sephadex G50 matrix slurry in an efflux buffer into a 1.5 cm... 

A pump is necessary to pack, unpack, and provide buffer from the slurry preparation tank to the column. The ideal pump provides constant pressure and flow rate at low shear stress. Because of shear stress reasons rotating parts have to be avoided, therefore diaphragm pumps are preferred. To dampen the pulsing characteristic of a diaphragm pump, typically 2 or 3 pistons are used. 

Check of the packing procedure The packing procedure could potentially create a mechanical stress to the stationary phase and break the silica beads, leading to fines in the column. This mechanical stress could be linked to the slurry preparation (inappropriate mixing device, transfer pump), to the hydraulic pressure, and so on.. . . Most of the packing suppliers assist their customers with detailed protocols for an efficient column packing. 

A scheme of Mobil process starting from coal is outlined in Fig. 6 and Table 4 presents a typical product distribution (52). More than 75 % of the produced hydrocarbons are in the C5 to Ci range and their content in aromates is high giving a high RON. The MTG process has been studied in fixed and fluidized bed reactors (52). Demonstration plants will be erected in New Zealand and West Germany. Process studies in bubble column slurry reactors are in preparation. 

Slurry pack the stationary phase prepared above into a 50 x 4.6 mm stainless steel column using an Alltech HPLC column slurry packer (12). Slurry solvent 1/1 (v/v) mixture of toluene and cyclohexanol. Pressurizing solvent heptane. Packing pressure 6000 psi. 

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