Preparative layer chromatography application

Application of Preparative Layer Chromatography for the Separation of Secondary Metabolites from Plant Tissues... 

Chapter 12 Application of Preparative Layer Chromatography to Lipids.299... 

TLC of larger quantities of materials (10 to 1000 mg) on thick layers (1-5mm), for the purpose of isolating separated substances for further analysis or use, is called preparative layer chromatography (PLC). Most preparative applications are carried out on 20 x 20 silica gel or alumina plates with a layer containing a fluorescent indicator to facilitate nondestructive detection. 

The method used for application of sample solutions is determined by whether HPTLC, TLC, or preparative layer chromatography (PLC) and qualitative or quantitative analysis are being performed. Sample volumes of 0.5-5 pi for TLC and 0.1-1 pi for HPTLC are applied manually to the layer origin as spots using fixed volume glass micropipets, such as Drummond Microcaps or selectable volume 10 or 25 pi digital microdispensers. In addition, many manual and automated instruments are available for sample application, especially for quantitative HPTLC. 

A good description of all important areas of preparative layer chromatography, theory and a wide range of applications (e. g. the use of PLC for isolation and identification of unknown compounds from the frankincense resin (Ohbanum), strategies for finding marker substances). 

Isolation procedures for Sceletium alkaloids have generally relied on column chromatography over alumina and/or silica gel for the separation and purification of the major alkaloids, with rqieated preparative-layer chromatography often necessary for separation of the minor bases. In one instance high-pressure liquid chromatography was used for purification of an alkaloid. This latter technique is likely to find increasing application in the future for isolation of the minor alkaloids of this family. 

Numerous works have been published on the experimental technique of TLC which will not be discussed further except in so far as is relevant to its application to additive identification. Dohmann [1] provides an excellent short review of techniques available. He discusses TLC in the normal sense of the word, i.e., with plate layers up to 250 pm thick and 20 cm x 20 cm or 20 cm x 8 cm in area and also discusses preparative layer chromatography which, with some loss in resolution, can separate considerably larger quantities of compounds on plate layers up to 2 mm thick and 100 cm x 20 cm in area. 

Circular development of TLC plate, 27 Classical preparative layer chromatography (CPLC), 307,308-317 applicability of, 317... 

Sample application, 20-23 application of spots, 20-21 choice of sample solvent, 20 formation of bands, 21-22 for preparative layer chromatography, 22-23 Sample preparation, 9-16 cleanup of extracts by column chromatognqrhy, 11 cleanup of extracts by solvent partitioning, 10-11 deproteinization, 18 derivatization, 18 desalting procedures, 14-15 direct application of sample solutions or extracts, 9-10... 

Preparative layer chromatography (PLC) is carried out on thicker layers with application of larger weights and volumes of sample to separate and recover from 10 to 1000 mg of compounds for further analysis. " ... 

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. 

High performance liquid chromatography (HPLC) has been by far the most important method for separating chlorophylls. Open column chromatography and thin layer chromatography are still used for clean-up procedures to isolate and separate carotenoids and other lipids from chlorophylls and for preparative applications, but both are losing importance for analytical purposes due to their low resolution and have been replaced by more effective techniques like solid phase, supercritical fluid extraction and counter current chromatography. The whole analysis should be as brief as possible, since each additional step is a potential source of epimers and allomers. 

---