Column chromatographic procedure

Many column chromatographic procedures have been described for the commercial separation and purification of neomycin following fermentation. 

The major difference between HPLC and the old column chromatographic procedures is the pressure applied to drive the mobile phase through the column. This requires a number of improvements in the equipment, materials used for separation, and the application of the theory. HPLC offers major advantages in convenience, accuracy, speed, and the ability to carry out difficult separations. Comparisons to and relative advantages of HPLC over classical LC and GC are given below (see Sections 15.1 and 15.2) to provide the reader a better appreciation of this technique. The readers are encouraged to look up an excellent classical text on HPLC by Snyder and Kirkland [2]. A short review of... 

A modification of the column chromatographic procedures which employs back adsorption and elution lias been described by Samgadharan et al. (28). However, although the specific activities of these preparations are reported to be comparable to those obtained by the procedure of Pontremoli et al., no evidence for the purity or homogeneity of the preparations was given. 

However, Shaikh demonstrated that the aforementioned traditional methods are inappropriate to recover completely lysophospholipids as well as acidic phospholipids classical Folch gave 85-90% recovery of LPC and LPE, whereas Bligh and Dyer yielded only 75-80% recovery. Extraction with a mixture of chloroform and methanol, on the other hand, provided nearly complete recovery of acidic and lysophospholipids, but up to 15% losses were observed during subsequent washing, according to Folch. These losses could be circumvented by purification of the crude extract on Sephadex G-25, but this column chromatographic procedure is quite time-consuming. 

Beta-carotene as determined in fruits and vegetables is used as a measure of the provitamin A content of foods. The column chromatographic procedure, which determines this content, does not separate a-carotene, p-carotene, and cryptoxanthin. Provitamin A values of some foods are given in Table 6-3. Carotenoids are not synthesized by animals, but they may change ingested carotenoids into animal carotenoids—as in, for example, salmon, eggs, and crustaceans. Usually carotenoid content of foods does not exceed 0.1 percent on a dry weight basis. 

The volume of the reaction mixture used with the HPLC assay was only about one-fifth the volume usually required with other assay methods, resulting in a considerable saving in reagents. The reaction was terminated with perchloric acid, the pH of the solution was returned to about 8 with potassium carbonate, and the sample was clarified by centrifugation. First the supernatant solution was purified using the double-column chromatographic procedure mentioned above, and then the samples were injected onto the HPLC column and analyzed for Dopa. 

Arylsulfohydrolase C has been purified to homogeneity from human placental and rat liver microsomes (Moriyasu et al., 1982 Burns, 1983 Noel et al., 1983) by using multiple-column chromatographic procedures. The purified human enzyme is a glycoprotein with Stake s radius and sedimentation coefficient values of 56 A and 4.85 S, respectively. In the purified state this enzyme still has traces of Triton X-100 and has a molecular weight of... 

The same column chromatographic procedure was used to termine... 

Griddle [43] has described a column chromatographic procedure for the identification and semi-quantitative determination of plasticisers in PVC. In this procedure the plasticiser is first Soxhlet extracted from 1 to 2 gram of PVC sample using anhydrous diethyl ether. Ether is then evaporated from the extract and residual traces of PVC precipitated by the addition of 2 ml of absolute ethanol. Following filtration of any polymer, the ethanol is finally evaporated off to provide a PVC free plasticiser extract. 

Sephadex is a modified dextran of bacterial origin and is used in numerous modifications ia gel filtration. This is mainly a column chromatographic procedure which permits separation of molecules on the basis of their differing sizes. This means that only those substances can be separated which differ sufficiently among themselves in molecular size, as for example proteins, peptides, enzymes, hormones, nucleic acids etc. 

Before the introduction of HPLC, several different liquid column chromatographic procedures to separate mixtures of Bg vitamers from each other were developed. Resolution of mixtures of pure vitamins was found to be quite simple. However, application to the analysis of food and biological material was difficult, mainly due to the low concentrations of the vitamers encountered and unsatisfactory means of detection. Quantification often involved laborious microbiological determination for the different Be vitamers in column eluate fractions (60). 

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