Chromatographic purification methods

The solvent effluent was checked at various time Intervals by a thin layer chromatographic (TLC) technique. The first eluted product was collected and dried under vacuum. A white powder-like product (DEPPE resin) was obtained with an overall yield of approximately 80%. Infrared and NMR spectra confirmed the product structure, as shown in Figure 1 and 2. For production of larger quantities, the chromatographic purification method was tedious and it was found that the product could be purified by repeated washings of the product with a solution containing 50 parts methanol to one part water. 

Has been purified by co-distillation with ethylene glycol (boils at 197.5°), from which it can be recovered by additn of water, followed by crysm from 95% EtOH, benzene, toluene, a mixture of benzene/xylene (4 1), or EtjO. It has also been chromatographed on alumina with pet ether in a dark room (to avoid photo-oxidation of adsorbed anthracene to anthraquinone). Other purification methods include sublimation in a N2 atmosphere (in some cases after refluxing with sodium), and recrystd from toluene [Gorman et al. J Am Chem Soc 107 4404 1985]. 

The lipophilicity of this phosphate protective group helps in the chromatographic purification of oligonucleotides. It is removed by the oximate method. ... 

Purification of aequorin. The purification method of aequorin reported by Shimomura et al. (1962) was essentially the repetition of column chromatography on DEAE-cellulose, the only usable, efficient chromatographic adsorbent available at the time. Since then, various different types of chromatographic media have been developed, and the purification method has been steadily improved. 

The purification method given above may be improved by utilizing various new chromatographic media, and the yield of the active photoprotein may be increased by utilizing catalase to remove traces of H2O2 in solutions. 

Locke, BR Carbonell, RG, A Theoretical and Experimental Study of Counteracting Chromatographic Electrophoresis, Separation and Purification Methods 18, 1, 1989. 

Adsorption, a surface phenomenon, is the basis of many gas or liquid mixture separation and purification methods. It is also the basis of adsorption chromatographic methods used for the analysis of complex mixtures. The knowledge of adsorption mechaiusms is useful in choosing the suitable systems providing optimum separation. 

Silica-supported reagents have been exploited as nontoxic, inexpensive, reusable, and environmentally acceptable catalysts for developing stoichiometric reaction methods in organic chemistry and specifically in carbohydrate chemistry. Apart from being easy to handle and to store, these systems allow facile workup, the catalyst being removed by simple filtration, and the reaction products isolated by chromatographic purification, if necessary. 

Many chromatographic methods such as permeation chromatography, column chromatography, and size exclusion chromatography have been used to purify CNTs. The size exclusion chromatography (SEC) is the only carbon nanotube purification method in the literature that is not subjected to the acid treatments which tend to create the carboxylic functionality on CNTs. 

The alcoholysis of the cyclic phosphate of catechol by alditols can lead, after acid hydrolysis of intermediate, cyclic phosphates, to the selective formation of phosphoric esters of the primary hydroxyl groups in the alditols. Thus, erythritol and D-mannitol afford, after chromatographic purification of the reaction products, their 1-phosphates in yields of 31 and 38%, respectively.217 The method was used to convert riboflavine into riboflavine 5 -phosphate.218 1-Deoxy-1-fluoro-L-glycerol has been converted into the 3-(dibenzyl phosphate) in 54% yield by selective reaction with dibenzyl phosphorochloridate. 219... 

Several variations on these production methods also exist, such as the use of immobilized CGTase (2i, 22), continuous ultrafiltration 23) and the use of isoamylase to increase CD yield. Variations of purification methods include the addition of glucoamylase to degrade non-CD starch hydrolysates to simply separation and the use of various S3mthetic ion exchange resins in chromatographic separations 24-26) and acuity columns (27),... 

If the laboratory worker does not know of a reference to the preparation of a commercially available substance, he may be able to make a reasonable guess at the synthetic method used from published laboratory syntheses. This information, in turn, can simplify the necessary purification steps by suggesting probable contaminants. However, for other than macromolecules it is important that at least the NMR and IR spectra of the substance be measured. These measurements require no more than two to three milligrams (which are recoverable) of material and provides a considerable amount of information about the substance. Three volumes on the NMR spectra [C.J.Pouchert and J.Behnke, The Aldrich Library of C and FT-NMR Spectra, Vols 1—3, Aldrich Chemical Co., Inc, Milwaukee, Wl, 1993], and one on the infrared spectra [C.J.Pouchert, The Aldrich Library of FT-IR Spectra, 3nd ed, Aldrich Chemical Co., Milwaukee, Wl, 7959], as well as computer software [FT-IR Peak-search Data Base and Software, for Apple HE, IIC and II Plus computers and for IBM PC computers, Nicholet Instruments, Madison, Wl, 1984] contain data for all the compounds in the Aldrich catalogue and are extremely useful for identifying compounds and impurities. If the material appears to have several impurities these spectra should be followed by examination of their chromatographic properties and spot tests. Purification methods can then be devised to remove these impurities, and a monitoring method will have already been established. 

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