Applications of thin-layer chromatography

TLC finds application in several areas in the field of lipids. 

Purification, pre-purification of samples and assessment of purity. TLC has often been used for purification purposes. It is an ideal and inexpensive tool to purify small quantities of lipid samples. In addition, TLC has also been used for pre-purification of samples before chromatographic analysis. We generally purify triglycerides of tissue samples by TLC before analysis by HPLC. Similarly, the derivatized methyl esters are purified by TLC before analysis by gas chromatography. Alternatively, the purity of a given sample. 

Identification. The structure of a compound can be identified by co-chro-matography with a reference standard of known structure. Of course, this needs to be further verified by other analytical techniques such as MS, IR, and NMR. 

Process and reaction monitoring. We have used TLC to monitor the time required for completion of the methylation reaction (Shantha, Decker and Hennig, 1993) and to study the formation of artifacts due to methylation of phthalates present in lipid samples (Shantha and Ackman, 1991b). TLC has been used to study the extent of hydrolysis of lipase-catalysed hydrolysis of triglycerides, phospholipase-catalysed hydrolysis of phospholipids and to study the activity of the enzymes. We have used TLC to study the extent of synthesis of acylated amino acids, and TLC has also been used to study the success of radiosynthesis. 

Determination of cholesterol in foods. Jian, Xuexin and Ai (1996) have determined the levels of cholesterol in foods by means of TLC. The separated lipids were sprayed with 5% phosphoric acid-alcohol solution to give coloration sterols. They found this method comparable to that of GC. 

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The currently most important fields of application of thin-layer chromatography be seen in Fig. 1. The proportion of publications in the fields of pharmacy and vironmental analysis has increased over that in previous years. There has also beer appreciable increase in the fields of clinical and forensic chemistry and in biochemis... 

Fig. 1 Fields of application of thin-layer chromatography (TLC/HPTLC) during the pei 1988-1991.

Analysis of On-Site Wastewaters for Pesticides by Thin-Layer Chromatography. A field method to identify qualitatively and semi-quantitatively the pesticide constituents of a pesticide-laden wastewater was developed. The field method was developed using thin-layer chromatography (TLC). TLC gives a presumptive test for the presence of specific pesticides and within 30 minutes an estimate of their concentrations. TLC may also reveal the presence of unknown substances. The field application of thin-layer chromatography requires a skilled chemist, but no expensive equipment. The following protocol describes the on-site use of TLC. 

In both of these field tests, the application of thin-layer chromatography was essential for characterizing the pesticides in the water and in monitoring the progress of their removal by the carbon filtration system. 

Early applications of thin-layer chromatography in corticosteroid analysis were mainly based on use of phenylhydrazine in sulfuric acid as a spray reagent for derivatization of the analytes (529, 530). Later applications involved use of other spray reagents including phosphoric acid in methanol, tetrazolium blue. 

Chandler W.T. Bolleter, Application of Thin-Layer Chromatography for Improving the Continuous TNT Process , JChromatogr 56,173—79 (1970) 46) R. Jenkins H J. Yallop The... 

Touchstone, J.C., Techniques and Application of Thin Layer Chromatography, John Wiley, New York, 1985. 

T. Okumura, Application of thin-layer chromatography to high performance liquid chromatographic separation of steroidal hormones and cephalosporin antibiotics, J. Liquid Chromatogr., 4 1035 (1981). 

Basis and pharmaceutical applications of thin layer chromatography... 

Basis and pharmaceutical applications of thin-layer chromatography TABLE 10.7 BINDERS USED FOR STATIONARY PHASE PLANAR CHROMATOGRAPHY 455... 

Senf, H. J. Applications of thin-layer-chromatography in inorganic analysis. 2. Chem. 6, 102(1966)... 

Ackman, R. G., Application of thin-layer chromatography to lipid separation, in Analysis of Fats, Oils and Lipoproteins (G. E. Perkins, ed.), American Oil Chemical Society, Champaign, IL, 1991, pp. 60-82. Christie, W. W., Lipid Analysis, 2nd ed., Pergamon Press, Oxford, 1982. 

Ackman, R.G. Application of Thin-Layer Chromatography to Lipid Separation. In Analysis of Fats, Oils and Lipoproteins Perkins, G.E., Ed. Amer. Oil Chem. Soc. Champaign, IL, 1991 60-82. 

Currendy, the most important fields of application of thin-layer chromatography are pharmacy (30%), biochemistry, forensic chemistry, and clinical chemistry (25%), environmental (15%), food analysis and cosmetology (10%), inorganic substances (5%), and various other fields (15%). The number of publications in the field of pharmacy steadily increases. 

P. Fasella, A. Giartosio, and C. Turano, Applications of thin-layer chromatography on Sephadex to the study of proteins, in Thin-Layer Chromatography (G. B. Marini-Bettolo, ed.), Elsevier, Amsterdam, 1964, pp. 205-211. 

Two monographs devoted to the principles and applications of thin-layer chromatography are B. Fried and J. Sherma, Thin Layer Chwmatography, 4th ed. New York Dekkcr. 1999 R. Hamilton and S. Hamilton, Thin-Layer Chminatography. New York Wiley, 1987. For recent reviews, see J. Sherma, Anal. Chem., 2002, 74. 2653 J. Sherma, 2000, 72, 9R C. F. Poole and S. K. Poole, Ann/. Chem.. 1994, 66. 21A. 

A review of the applications of thin layer chromatography for the analysis of foodstuff was written by Sherma [5], A book entitled TLC, Reagents and Detection Methods is an extensive review of the available physical and chemical TLC revealing agents [6]. 

W16. Whelan, F. J., and Plaa, G. L., The application of thin layer chromatography to sulfobromophthalein metabolism studies. J. Toxicol. Appl. Pharm. 6, 457-463... 

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