Thin-layer chromatography Raman spectroscopy

Additional methods which so far have been of only limited interest for the quantitative study of redistribution equilibria are mass spectrometry (313), Raman (68), and infrared (110) spectroscopy. It can be visualized that methods such as microwave spectroscopy, thin-layer chromatography, or Mdssbauer spectroscopy may be of interest in the near future. 

GC- and LC-MS (Fig. 2), although others have also used other techniques including Fourier transform infrared spectroscopy, thin layer chromatography, high-pressure liquid chromatography, and Raman spectroscopy. The major techniques as judged by current number of publications will be discussed below. 

Separation of amino acids and their identification in different mixtures are frequent tasks encountered in biochemistry. Thin layer chromatography is a fast, simple, and inexpensive approach to attain this goal. Because some of the components are UV-inactive, other methods, such as vibrational spectroscopy, should be applied for detection and identification. Comparative study based on Raman spectroscopy of thin layer chromatography spots of some weak Raman scatterers (essential amino acids) was carried out using four different visible and near-infrared laser radiation wavelengths 532, 633,785, and 1064 nm. The best results were obtained with simple silica gel plates. 

The analytical technologies used In metabolomic investigations are nuclear magnetic resonance and mass spectrometry alone or in combination with liquid or gas chromatographic separation of metabolites (243). Other techniques include thin-layer chromatography, Fourier-transform infrared spectrometry, metabolite arrays, and Raman spectroscopy. 

Raman and IR spectroscopy may be used to analyse spots on thin layer chromatography (TLC) plates. Unlike other methods, such as mass spectrometry or NMR, the spectrum may be obtained in situ without the need of scraping the spot from the plate and extracting the substance from the sihca matrix. Dispersive Raman miaos-copy has been used to collect spectra from active dmg substance on a plate [18,88]. 

Everall, N. J., Chalmers, J. M., and Newton, I. D. (1992). In situ identification of thin layer chromatography fractions by Fourier transform Raman spectroscopy. Appl. 

Fredericks, P., DeBakker, C., Martinez, E. (1992). In situ characterization by FT-Raman spectroscopy of compounds separated on a thin layer chromatography plate. Proc. SPIE-Int. Soc. Opt. Eng. 1575 468 -469. 

Direct identification methods for vibrational spectra of high-performance thin-layer chromatography (HPTLC) spots such as infrared and Raman spectrometries are limited by the required high quantities of substances. However, recent findings of an enhanced Raman scattering for various compounds adsorbed at metal surfaces give new potential for analytical applications of Raman spectroscopy. ... 

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