Column chromatography columns

Column Chromatography Column Chromatography is a useful separation technique for mixtures resulting from intermediate to small scale synthetic processes. For example, nitroferrocene is conveniently isolated from a mixture of the product, ferrocene, and l,r-dinitroferrocene by chromatography on Activity I basic alumina at about the 100-g scale (Chapter 7, Section XI). 

The urine of people who are heavy smokers contains mutagenic chemicals, chemicals that cause mutations in biological cells. Bioanalytical laboratories can analyze urine samples for these chemicals, but the samples must be cleaned up first prior to extraction with methylene chloride. The procedure for this cleanup utilizes an open column chromatography. Columns several inches tall and about an inch wide are prepared by packing them with an adsorbing resin that has been treated with methyl alcohol. The urine samples are passed through these columns as part of the sample preparation scheme. 

Another type of mass transfer equipment, shown in Figure 6.2d, is normally referred to as the packed- (fixed-) bed. Unlike the packed column for gas-liquid mass transfer, the packed-bed column is used for mass transfer between the surface of packed solid particles (e.g., catalyst particles or immobilized enzyme particles) and a single-phase liquid or gas. This type of equipment, which is widely used as reactors, adsorption columns, chromatography columns, and so on, is discussed in greater detail in Chapters 7 and 11. 

Collecting fractions during column chromatography. Column material and elution procedure are chosen to effect optimal separation of the desired protein. 

In 5 ml of isopropyl alcohol were dissolved 1.5 g (0.01 mole) of 3-nitrobenzaldehyde, 2.6 g (0.01 mole) of l-benzyl-3-acetoacetyloxypyrrolidine, and 1.3 g (0.01 mole) of p-aminocrotonic acid methyl ester and then the solution was refluxed for 8 hours. The solvent was distilled off under reduced pressure, the residue obtained was dissolved in a small amount of chloroform, and the solution was applied to silica gel column chromatography (column diameter 1.5 cm, height 20 cm, and about 200 ml of chloroform was used as the eluent). The eluates were collected and concentrated to give 3.4 g of oily... 

Column Chromatography. Column chromatography of the solvent refining or liquefaction samples was done in a manner described previously (II). The sample (.2 g) was dissolved in THF or chloroform and pre-adsorbed on 2 g of neutral alumina. The solvent was removed under vacuum, and the alumina with sample was added to an 11-mm o.d. glass column containing an additional 6g of neutral alumina (Activity I). Separation into saturates, aromatics, and various polar materials was done by elution with hexane, toluene, chloroform (two fractions), and 9 1 THF/ethanol. 

A direct method for testing RNA-protein interaction in vitro is by affinity-precipitation or -chromatography. Two molecules interact if specific purification of one of them leads to co-purification of the other molecule. This approach is often referred to as the pulldown method . Different experimental designs can be used One possibility is to let the RNA-protein complex form in solution under native conditions, and then purify the complex by binding a high affinity tag, present in either the RNA or the protein to beads. The physical separation may be accomplished by low speed centrifugation (batch approach) or by column chromatography (column... 

The cysteinato compound A (7 g, 0.011 mol) is dissolved in 1 M HCl (70 mL), the solution is stirred for 30 min and filtered, and Sephadex G-10 column chromatography (column diameter 3.5 cm, length 60 cm) is used for separation (eluent 1 M HCl 5h). The second yellow band contains the aqua ion [80% typically 300 mL of a 0.03 M (per dimer) solution]. The first (yellow) and third (yellow) bands contain small amounts of [Mo204(aq)] " and [Mo202S2(aq)], respectively. Electronic spectral data are given in Table I.f... 

Column chromatography was first developed by the American petroleum chemist D. T. Day in 1900. 

The nitration of the 2-anilino-4-phenylselenazole (103) is much more complicated. Even careful nitration using the nitrate-sulfuric acid method leads to the formation of a mixture of variously nitrated compounds in an almost violent reaction. By the use of column chromatography as well as thin-layer chromatography a separation could be made, and the compounds could be partly identified by an independent synthesis. Scheme 33 shows a general view of the substances prepared. Ring fission was not obser ed under mild conditions. 

Chromatography column (coiled to conserve space m oven)... 

Elution volume, exclusion chromatography Flow rate, column Gas/liquid volume ratio Inner column volume Interstitial (outer) volume Kovats retention indices Matrix volume Net retention volume Obstruction factor Packing uniformity factor Particle diameter Partition coefficient Partition ratio Peak asymmetry factor Peak resolution Plate height Plate number Porosity, column Pressure, column inlet Presure, column outlet Pressure drop... 

A typical column chromatography experiment is outlined in Figure 12.4. Although the figure depicts a liquid-solid chromatographic experiment similar to that first used by Tswett, the design of the column and the physical state of the... 

A common liquid chromatography column is somewhat larger in diameter than a nanocolumn. Consequently, the flow of solution along such a column is measured in terms of one or two milliliters per minute, and spraying requires the aid of a gas flowing concentrically around the end of the inlet tube (Figure 10.2c). An electrical potential is still applied to the end of this tube to ensure adequate electrical chaiging of the droplets. 

These factors make it necessary to reduce the amount of solvent vapor entering the flame to as low a level as possible and to make any droplets or particulates entering the flame as small and of as uniform a droplet size as possible. Desolvation chambers are designed to optimize these factors so as to maintain a near-constant efficiency of ionization and to flatten out fluctuations in droplet size from the nebulizer. Droplets of less than 10 pm in diameter are preferred. For flow rates of less than about 10 pl/min issuing from micro- or nanobore liquid chromatography columns, a desolvation chamber is unlikely to be needed. 

Schematic diagram of an orthogonal Q/TOF instrument. In this example, an ion beam is produced by electrospray ionization. The solution can be an effluent from a liquid chromatography column or simply a solution of an analyte. The sampling cone and the skimmer help to separate analyte ions from solvent, The RF hexapoles cannot separate ions according to m/z values and are instead used to help confine the ions into a narrow beam. The quadrupole can be made to operate in two modes. In one (wide band-pass mode), all of the ion beam passes through. In the other (narrow band-pass mode), only ions selected according to m/z value are allowed through. In narrow band-pass mode, the gas pressure in the middle hexapole is increased so that ions selected in the quadrupole are caused to fragment following collisions with gas molecules. In both modes, the TOF analyzer is used to produce the final mass spectrum.

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