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Layers comparison with columns

The Determination of the Fatty Acid Composition of Serum Lipids Separated by Thin-Layer Chromatography and a Comparison with Column Chromatography... [Pg.29]

Snyder, L. R., and Saunders, D. L. (1969). Resolution in thin layer chromatography with solvent and adsorbent programming. Comparisons with column chromatography and normal thin layer chromatography. J. Chromatogr. 44 1-13. [Pg.143]

Column and thin-layer chromatography (TLC) came into use at about the same time as GLC, with the latter widely accepted because of its speed, ease of use, versatility, resolving power, and, probably most important, ease of visualization. Thin-layer chromatography has been particularly useful in the separation and nondestructive recovery of lipid classes. Tentative identifications can be made by comparison with known compounds, and purity can be checked. Jensen et al. (1961) may well have been the first group to separate milk lipid classes with TLC when they used the technique to obtain diacylglycerols from lipo-lyzed milk lipids. [Pg.171]

Not on scale in fact, the thickness, 5, of the diffusion boundary layer is very small in comparison with the height of the column of the liquid phase. [Pg.214]

The procedures of partial wetting, evaporation and condensation depend on several factors and basically influence both the separation of the analyte spots and the speed of the mobile phase movement 39,40. A beneficial effect of the evaporation of the running mobile phase from the thin-layer plate and wetting the stationary phase with the mobile phase is that spots with Rf values over 0.5 are concentrated. Thereby, the efficiency of the TLC system can be highly increased in comparison with the column technique. [Pg.457]

Recently, veratroylpseudaconine (24) was isolated by a combination of pH gradient, thin layer, and column chromatographic techniques as one of the major alkaloids of the methanolic extracts of the roots of A. falconeri (42). The basic hydrolysis of 24 yielded veratric acid and the crystalline parent amino alcohol, pseudaconine (26). Comparison of alkaloid 24 with an authentic sample of veratroylpseudaconine, prepared by heating pseu-daconitine (21) with 0.1 N H2S04 in a sealed tube, showed identity. The structure of veratroylpseudaconine as 24 was also established independently by a 13C NMR analysis (44). Alkaline hydrolysis of 25 yielded acetic acid, veratric acid, and pseudaconine (26). Finally, structure 25 was established for diacetylpseudaconitine by comparison with an authentic sample, which was prepared by acetylation of 21 with acetic anhydride and p-toluenesulfonic acid. [Pg.10]

Traditional open column liquid chromatography (LC) suffers poorly in comparison with the thin layer method in that it is a fairly slow process which requires large amounts of packing material, eluant and sample. The major disadvantages of LC methods are with speed, scale, resolution and characterisation. [Pg.50]

The overall method for gasoline requires no sample preparation other than the addition of internal references. The method is fast since samples may be run at 3-min intervals, interference-free and specific for MMT. Analysis time comparison is favourable with respect to atomic absorption analysis which typically required about 15 min per sample when run in batches. Further, the procedure is readily adapted for use with open tubular columns. Porous layer open tubular columns (PLOY) are best suited to accommodate the direct injection of gasoline samples. The improvement in analysis time for MMT determination by the latter method may outweigh the somewhat poorer limit of detection resulting from limitations on the sample size. [Pg.528]

Figure 10.14 (a] Schematic side view of the capillary rise of water in comparison with a ray-tracing illustration of spontaneous water imbibition in Vycor. (b] A liquid column has advanced up to the height A parabolic fluid velocity profile along with preadsorbed water layers beyond h t) and a shaded resting boundary layer are sketched for the nanocapillaiy in panel [a), (with permissions from ref )... [Pg.385]

Thin layer chromatography (TLC) is a separation technique that lacks quantitative precision, sensitivity, and separation efficiency in comparison with methodologies involving column separation. However, TLC methods have been developed and commonly employed for the separation and determination of flavonoids since TLC is a quick, convenient, and inexpensive technique that does not require complex instrumental equipment, with the ability to assay many samples in parallel on a single TLC plate. It can also be used to control isolation in column chromatography and, to some extent, to identify analytes. [Pg.172]


See other pages where Layers comparison with columns is mentioned: [Pg.445]    [Pg.225]    [Pg.410]    [Pg.138]    [Pg.341]    [Pg.259]    [Pg.397]    [Pg.775]    [Pg.594]    [Pg.145]    [Pg.19]    [Pg.594]    [Pg.133]    [Pg.171]    [Pg.341]    [Pg.102]    [Pg.335]    [Pg.13]    [Pg.483]    [Pg.478]    [Pg.231]    [Pg.265]    [Pg.426]    [Pg.309]    [Pg.375]    [Pg.176]    [Pg.52]    [Pg.4793]    [Pg.4794]    [Pg.85]    [Pg.553]    [Pg.25]    [Pg.50]    [Pg.120]    [Pg.175]    [Pg.176]    [Pg.410]    [Pg.216]    [Pg.1191]    [Pg.67]   
See also in sourсe #XX -- [ Pg.501 , Pg.516 ]




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