Thin-layer chromatography experimental procedures

Phospholipase A2 Action. Incubation of phosphatidylserine with phospholipase A2 obtained from Crotalus adamanteus or Naja Naja snake venom will show that the serine-containing phosphoglyceride was smoothly and completely converted to a lysophosphatidylserine with liberation of 1 mol of fatty acid per mole of lipid P. The experimental procedure was the same as the one described before in this and in the previous chapter. The products of the reaction can be recovered by thin-layer chromatography on Whatman K6 plates in a solvent system of chloroform-acetone-methanol-acetic acid-water (4.5 2 1 1.3 0.5, v/v). 

A number of other surrogate procedures have been developed. These include the use of reverse-phase thin-layer chromatography (TLC) (Bruggeman et al. 1982 Renberg et al. 1985) to measure relative mobilities (Rm) or reverse-phase high-performance liquid chromatography (HPLC) to measure capacity factors (Veith et al. 1979b). These values are then correlated with experimentally established Pow values for standard compounds, and the correlation is then used to calculate values of Pow for the unknown compounds. 

Thin-layer gel chromatography (TL GPC) is a technique utilizing the flat bed of gel supported by a plate of glass, metal or plastics. The experimental arrangement of TL GPC is similar to conventional thin-layer chromatography, but since the wet gel beds are most often used, gravitation is employed for the generation of flow instead of capillary elevation. Evidently, the procedures of over-pressurized TLC may also be applied. 

The key step consisting of the cobalt-mediated [2+2+2] cycloaddition is shown in Scheme 2.103. The experimental procedure includes reflux under radiation with visible light until no starting material could be detected by thin layer chromatography (TLC) analysis. After removing volatile components in vacuo, the residue was treated with FeCls-HiO and purified by chromatography to afford steroids in 33% yield. 

The purpose of this book is to present practical, comprehensive information on the field of chiral thin layer chromatography (TLC), As with the past book we edited for CRC/Taylor Francis (Preparative Layer Chromatography, 2006), this is the first book on the title topic to become available. The book s coverage of state-of-the-art chiral TLC is divided into two main sections theory and procedures (Chapter 1 to Chapter 9) and applications (Chapter 10 to Chapter 15). The book will be of great benefit to scientists with diverse interests for better understanding and wider use of chiral TLC. It will be a critical resource for researchers, analysts, and teachers with limited to broad experience in TLC and chiral separations because of its blend of introductory, background, and detailed, advanced experimental material. 

The latter procedure has so far been applied successfully (/) to a large number of silicas suitable for column chromatography (60-200 mesh). Attempts to extend these techniques to thin-layer silicas have not been successful. In the case of silicas with calcium sulfate binder, experimental values of 5,. and St appear quite variable and do not agree with values that can be inferred from surface area, pore diameter, and chromatographic activity data. This suggests that calcium sulfate in some way interferes with the silica-silane reaction. For thin-layer silicas without binder, erroneously low values of S jSf are obtained. This is believed to be due to... 

The various experimental procedures that have been developed for its determination in different biological materials could be conveniently divided into bloassay or biological methods, chemical methods, radioactive tracer determinations, enzymatic techniques, paper, column, thin layer, gas chromatography, high performance liquid chromatography (HPLC) and automated methods (ref. Table 2.4 for references to these techniques and their grouping). The methods for determination of ascorhigen have also been listed separately in Table 2.4. A. 

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