Chromatography, preparative

Sodium ionophore VI bis[(12-crown-4)methyl]dodecyl methyl malonate [80403-59-4] M 662.9. Purified by gel permeation or column chromatography. [Preparation and NMR data J Electroanal Chem 132 99 1982.]... 

Technique of thin-layer chromatography. Preparation of the plate. In thin-layer chromatography a variety of coating materials is available, but silica gel is most frequently used. A slurry of the adsorbent (silica gel, cellulose powder, etc.) is spread uniformly over the plate by means of one of the commercial forms of spreader, the recommended thickness of adsorbent layer being 150-250 m. After air-drying overnight, or oven-drying at 80-90 °C for about 30 minutes, it is ready for use. 

Huhn, G. and Muller, H., Polymer-coated cation exchangers in high-performance ion chromatography preparation and application, /. Chromatogr., 640, 57, 1993. 

Zeng, X. and Ruckenstein, E., Membrane chromatography preparation and applications to protein separations, Biotechnol. Prog., 15, 1003, 1999. 

J Rivier, R McClintock, R Galyean, H Anderson. Reversed-phase high-performance liquid chromatography preparative purification of synthetic peptides. J Chromatog 288, 303, 1984. 

Fujimoto, C., Maekawa, A., Murao, Y, Jinno, K., and Takeichi, T., An attempt directed toward enhanced shape selectivity in reversed-phase liquid chromatography preparation of the dodecylaminated beta-cyclodextrin-bonded phase. Anal. Sci., 18, 65, 2002. 

J. D. Protein-doped monolithic silica columns for capillary liquid chromatography prepared by the sol-gel method applications to frontal affinity chromatography. Anal Chem... 

Brocklehurst, K., Carlsson, J., Kierstan, M.P.J, and Crook, E.M., Covalent chromatography. Preparation of fully active papain from dried papaya latex, Biochem. J., 133, 573-584, 1973. 

Denet, F. (2002) Devdoppement et Moddisation de Precedes de Chromatographie Preparative avec Eluant Supercritique, These de doctoral INPL. 

Polar compounds or compounds which decompose at elevated temperatures in gas chromatography, can often be converted to more stable derivatives prior to gas chromatography. Preparation of derivatives may also add heteroelements and render certain compounds more responsive to element selective detectors. This latter technique can sometimes ease cleanup problems by effectively reducing the background against which one must quantify. Similar techniques are useful for confirmation of results obtained by other methods. 

Survey of general LC application areas Gel permeation chromatography Ion chromatography Preparative HPLC Compound synthesis The future Glossary References... 

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. 

As a rule, a separation method should be used for both purification and concentration of the sample. The classic method for peptides and proteins is a reverse-phase liquid chromatography preparation of the sample, followed by a concentration step (often lyophiliza-tion) of the fraction of interest. During those steps performed on very small quantities of sample, loss on the sample can occur if care is not taken to avoid it. Lyophilization, for instance, can lead to the loss of the sample absorbed on the walls of the vial. The use of separation methods on-line with the mass spectrometer often are preferred. Micro- or nano-HPLC [32,33] and capillary electrophoresis [34], both coupled mainly to electrospray ionization/mass spectrometry (ESI-MS), are used more and more. 

Eluents for high pressure liquid chromatography, preparation, 209... 

Lipopholic products are usually separated by extraction of the filtered broth, or the whole culture including the biomass, with water immiscible organic solvents, followed by separation of the solvent extracts and concentration in a vacuum evaporator. Chloroform, dichloromethane and ethyl acetate have been widely used as extraction solvents, however, 4-methyl-2-pentanone (methyl isobutyl ketone) appears to be the solvent of choice in the case of steroid substrates. Hydrophilic products, which cannot be extracted by organic solvents, can be isolated by ion exchange or by selective adsorption to polymeric resins (e.g., Amberlite XAD-resins). Resins of a wide range of polarity are available and lipophilic compounds can also be separated by this method. Final purification is accomplished in the usual way by crystallization, distillation or column chromatography. Preparative HPLC is a powerful tool for purification of small product quantities. 

DEAE-SEPHADEX A-50 CHROMATOGRAPHY PREPARATIVE DISC GEL ELECTROPHORESIS ... 

Zeng XE and Ruckenstein E. Membrane chromatography Preparation and applications to protein separation. Biotechnol. Prog. 1999 15 1003-1019. 

Purify it by gel permeation or column chromatography. [Preparation and NMR data Shono et al. J... 

Identified by Tressl et al. (1981) after distillation-extraction, separation by chromatography, preparative GC, then capillary GC with either flame ionization or flame photometric (for sulfur-selective analysis) detector. Silwar et al. (1986) after simultaneous distillation-extraction used the two detectors simultaneously for quantifying the sulfur compounds (see Q.14). They found less than 0.01 ppm of this dithiolane in arabicas as well as in robustas. 

A solution of 3 (1.0 g, 4 mmol) in CHCI3 (100 mL) was shaken with aqueous sodium dithiorete until the organic layer became coiortess. The glassy residue obtained after evaporation was dissolved in dk>xane TEA (1.1) (100 mL) by heating 12 h on a steam bath. Evaporation and chromatography (preparative TLC - PhH.MeOH 9 1) gave 0.6 g of 4 (89%), mp 77-7B.3 C. 

The typical inner diameter of analytical gel chromatographic columns ranges from 2 to 8 mm. Recently, attempts were reported to apply packed capillary columns to gel chromatography. Preparative separations are performed in columns with diameters up to several decimeters. 

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