Columns packing apparatus

A number of commercial column packing apparatuses are available. One type, the ascending type, is a stirred can that pumps slurry upward into the pressure line and then down into the column. The descending type of packer is simply a slurry reservoir that attaches in place of the inlet end-cap and frit and is equipped with a pump connection at the top (Fig. 5.3). Manufacturers use 20,000-psi pumps to drive slurry into the column, but most laboratory packing apparatuses rely on pumps that reach a maximum of only 6,000-10,000psi. The pumps are run fully open until the pressure stabilizes. 

Most distillations conducted commercially operate continuously, with a more volatile fraction recovered as distillate and a less volatile fraction recovered as bottoms or residue. If a portion of the distillate is condensed and returned to the process to enrich the vapors, the Hquid is called reflux. The apparatus in which the enrichment occurs is usually a vertical, cylindrical vessel called a stiU or distillation column. This apparatus normally contains internal devices for effecting vapor—Hquid contact the devices may be categorized as plates or packings. 

Gamma, of a photographic emulsion 769 Gas chromatography 235 apparatus for, 235 column packing for, 238 derivatisation in, 236 detectors for, 240 elemental analysis by, 247 of metal chelates 237, 248 pyrolysis, 237... 

The analysis demonstrates the elegant use of a very specific type of column packing. As a result, there is no sample preparation, so after the serum has been filtered or centrifuged, which is a precautionary measure to protect the apparatus, 10 p.1 of serum is injected directly on to the column. The separation obtained is shown in figure 13. The stationary phase, as described by Supelco, was a silica based material with a polymeric surface containing dispersive areas surrounded by a polar network. Small molecules can penetrate the polar network and interact with the dispersive areas and be retained, whereas the larger molecules, such as proteins, cannot reach the interactive surface and are thus rapidly eluted from the column. The chemical nature of the material is not clear, but it can be assumed that the dispersive surface where interaction with the small molecules can take place probably contains hydrocarbon chains like a reversed phase. 

The columns used were dry packed using a packing apparatus (purchased from Mandle Scientific). The packing employed was CPG of pore sizes 1000, 2000 and 3000 X and 200-UoO mesh size. The colimins were calibrated using Dow and Polysciences monodispersed polystyrene latices. 

The coliomn was disconnected from the chromatograph and mounted on the packing apparatus which was then activated. This caused the packing in the col amn to further settle. Additional packing material was then added. The column was once again calibrated. 

Reversed-phase silica gel column Place a cotton wool plug at the bottom of a glass chromatography column. Pack 5 g of reversed-phase silica gel slurried with a solvent mixture of n-hexane-benzene-methanol (80 20 0.4, v/v/v) into the glass column. Place an anhydrous sodium sulfate layer about 1 -cm thick above and below the silica gel bed Bell jar-type filtering apparatus Buchner funnel, 11-cm i.d. 

Slurry packing techniques are required for the preparation of efficient columns with rigid particles of less than 20 micrometers in diameter. The same general packing apparatus. Figure 4.8, can be used to pack columns by the balanced-density slurry, liquid slurry, or the viscous slurry techniques. Down-fill slurry packing is the method of choice for small bore columns and packed capillary columns. 

Ctriunm ovetloading, 52 Column packing procedure, 125, 145,146 apparatus, 146-148... 

Fig. 9. Apparatus for sluijy packing of columns. After the properly fittul column tube is attached to the bottom of the reservoir, both are filled up with the slurry ofthe micropartic-ulate stationary phase. Thereafter a displacement liquid is pumped into the reservoir by the constant pressure pump, e.g., Haskel Model DST>I00, which is driven by preuurized air. Upon displacement, the slurry from the reservoir is filtered over the porous etal frit at the bottom of the column tubing which becomes densely packed with the partic s. By intermit-tently operating the liquid shut-off valve between the pump and the reservoirpressure waves can te generated in order to flirther compact the column packing. Reprinted from Bakalyar et at. U05) with permission from Spectra-Physics.

Whereas in the example just described the sample amount was about 50 mg, a similar procedure developed by another group 129) started with 4 g polyethylene copolymer. The sample was applied as a dilute solution in xylene and precipitated by very slow cooling (1.5 K/h) onto the Chromosorb P packing of a 500 x 127 mm column. The first separation was temperature-rising elution fractionation at a flow-rate of 20 ml/min and a Unear temperature increase by 8 K/h. The MMD of the fractions was measured by SEC at 145 °C in o-dichlorobenzene at 0.7 ml/min flow rate. The column set included a pair of bimodal columns 100 A and 1000 A plus a 4000 A column. The apparatus was equipped with an IR detector. The experimental data is computed to show the distribution of short-chain branching and of molar mass simultaneously. 

Columns consisting of particles of less than 30-50 jum in diameter are prepared most efAciently by slurry packing. Balanced-density slurry packing [11,12] is the most successful of such methods. In this technique, a supporting liquid is used which has the same density as that of the particles. This eliminates sedimentation problems. A typical balanced-density slurry-packing apparatus is shown in Fig.3.42. For the preparation of a... 

Dry-column flash chromatography. This technique has been developed from flash chromatography by L. M. Harwood.64 The principal feature is that suction is applied to the column packing, and eluting solvents are added in predetermined volumes with the column being allowed to run dry before the next fraction is added. Furthermore the apparatus is both simple and of easy operation. 

In a 50-ml three-necked flask are placed the carboxylic acid (0.01 mol), ethyl polyphosphate (6g, PPE) and purified chloroform (5 ml). The mixture is cooled in an ice bath and the flask is connected to a balloon containing ammonia gas ( 3 litres). Air in the flask is replaced with ammonia and the mixture is mechanically stirred at 0-5 °C for 30 minutes and then at room temperature for one and a half hours whereupon the mixture turns very viscous (1). The balloon is removed and PPE (10 g) is added. The stirring is continued at 80 °C until the reaction is complete (usually within several hours) the dehydration is monitored by t.l.c. analysis (1). The mixture is stirred with aqueous 25 per cent sodium carbonate solution (150 ml), and then extracted with benzene (3 x 40 ml CAUTION). The combined organic extracts are dried with sodium sulphate and evaporated. The residual oil is passed through a short column packed with silica gel ( 20g) and the product eluted with benzene. The eluate is evaporated and the residue purified by short path distillation under reduced pressure (Kugelrohr apparatus). 

Apparatus Use a 40- x 2.5-cm (id) glass column packed with Celite (Johns Mansville No. 595, or equivalent) prepared as described under Procedure. Dissolve 20 g of hydroxyl-amine hydrochloride in 500 mL of water, place the solution into a 2-L separatory funnel, and add 450 mL of butanol, 450 mL of chloroform, 300 mL of water, and 100 mL of hydrochloric acid. Agitate the mixture well, periodically venting the funnel. After settling, separate and store the bottom layer (organic), the Mobile Phase, and the top layer (aqueous), the Stationary Phase. 

High pressure continuously operated reactor. The design of the continuously operated apparatus is shown in Figure 2. An air operated high pressure pump delivered CO2 in the system. The gaseous fluid was dried when passing through columns packed with molecular sieves. The flow rate of C02 was 1.0 L per min. Equimolar solution of substrates (oleic acid and oleyl alcohol) was pumped into the system with an HPLC pump. Carbon dioxide and substrates were equilibrated in the saturation column. The reaction was performed in a... 

The experimental apparatus developed for citrus oil processing is shown in Figure 4. The empty column was equipped before the adsorption column in order to dissolve the raw oil completely in SC-C02 and to avoid the adsorption of waxes and pigments, where they were removed easily due to the small solubility in SC-C02. A pair of 0.5 m long and 9 mm i.d. columns packed with silica gel were used for adsorber. 

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