Chromatography concentrates

SFE-SFC operation consists of extraction, trapping, and transfer to the column for chromatography. Concentration of the solutes of interest before sample introduction to SFC may be achieved by ... 

Purified antibodies are usually prepared from whole serum by affinity chromatography. Concentration of affinity-purified specific antibodies is normally specified by the manufacturer in the antibody data sheet. When starting with a new... 

It is often desirable to go through a postlysis separation/concentration step prior to chromatography. Concentration methods involve the use of ammonium acetate and polyethylene glycol precipitation to further remove host proteins and small nucleic acids. These methods also reduce the volume of the sample (or the process streams) prior to chromatographic purification. The separation may also involve centrifugation and filtration to remove cell debris. 

An adaptation of the distribution constant defined in Equation (23-3) could be made for solutes in chromatojp-aphy. As in liquid-liquid extraction, however, solutes may be present in several chemical forms, and therefore a quantity analogous to the distribution ratio (Section 23-1), called the partition ratio, is preferred. The partition ratio must be a somewhat more broadly defined term than the distribution ratio in liquid-liquid extraction for two reasons. First, in chromatography, concentrations of solute in the two phases are usually unknown and may be unmeasurable, as when adsorption is important. Second, instead of the two phases being merely an aqueous phase and an immiscible organic solvent, in chromatography they can be any one of innumerable combinations of solid or liquid stationary phases and liquid or gas... 

Experimental work of Kalasz et al. resulted in the statement of the characteristics and basic rules of displacement chromatography. They conceived properties of the fully developed displacement train, factors affecting displacement development, efficacy of separation, analysis of displaced fractions, determination of displacement diagrams from Langmuirian isotherms, as well as selection of the column, carrier, and displacer for displacement chromatography. Concentration of the sample is a particular feature of displacement chromatography. However, the displacer in the carrier is also definitely concentrated through the development of the displacement train. 

Malt beverages Clean sample by celite colunn chromatography, concentrate methylene chloride eluate. GC-TEA NG 90% Hotchkiss et al. 1981... 

FIGURE 22.4 Comparison of infrared and liquid chromatography concentration profiles. 

For the two above approaches, it is recommended that the purification of the crude O-sulfated tyrosine-containing peptides be performed by re-versed-phase HPLC or MPLC using 0.1 M ammonium acetate buffer (pH 6.5) in the gradient system. Lower pH values (e.g., with application of the most common 0.1% trifluoroacetic-based buffers) can induce slow desulfuration during chromatography, concentration of the samples, and lyophilization. The ammonium acetate solution, although volatile, had to be lyophil-ized several times to gain salt-free pure peptides. 

Potassium oxalate added to sample and extracted with solvent to extract lipid dissolved in acetonitrite and extracted in hexane cleaned by column chromatography concentrated... 

Extract with solvent dean up by column chromatography concentrate extract... 

Extract is solvent u1trason1ca11y dean up column chromatography concentrate... 

The Sample. In the case of silica-gel layers the sample should be dissolved in the least polar solvent in which it is soluble. With a solution of the proper concentration, l-SpL should suffice to permit detection of the analyte of interest after chromatography. Concentrating may prove to be the best procedure with a dilute solution. However, dilute solutions can also be applied in the form of several successive aliquots. If the sample is too dilute, spreading of the application area can be prevented by accelerating evaporation of solvent with a stream of air blown over the area in question. A hair dryer is often used for this purpose. Correct application ensures that the separated zones will be both symmetrical and compact. 

P. Werkhoff and W. Bretschneider, Dynamic headspace gas chromatography concentration of volatile components after thermal desorption by intermediate cryofo-cusing in a cold trap. II. Effect of sampling and desorption parameters on recovery, J. Chromatogr. 488 (1987). 

Concentration by ion and ligand exchange chromatography Concentrated on Amberlite IR-120... 

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