Thin-layer chromatography coupled with mass spectrometry

Busch, K. L. Thin-Layer Chromatography coupled with Mass Spectrometry , in Handbook of Thin-Layer Chromatography, J. Sherma, B. Eried Chromatographic Science Series, Vol. 55, 1991, 183-209, Marcel Dekker, New York... 

Busch, K. L. (1996) Thin-layer chromatography coupled with mass spectrometry in Handbook of Thin-layer Chromatography (eds J. Sherma and B. Fried), Marcel Dekker, New York, pp. 241-72. 

Anderson, R.M., Busch, K.L. (1998) Thin-layer chromatography coupled with mass spectrometry interfaces to electrospray ionization. Journal of Planar Chromatography, 11, 336-341. 

Bush, K.L. 1991. Thin layer chromatography coupled with mass spectrometry, in Handbook of Thin Layer Chromatography, Sherma, J. and Fried, B., Eds., CRC Press/ Taylor Francis Group, Boca Raton, EL, Chapter 8. 

Most commonly used is the recording of UVA IS spectra, which are compared with spectral libraries. However, more informative is the recording of a FTIR- or Raman-spectrum in situ. These relatively recent developments to measure diffuse reflectance can now be carried out routinely. The in situ employment of MS after TLC detection is described in detail elsewhere (see Chapter 9, Thin Layer Chromatography Coupled with Mass Spectrometry), as well as the employment of radioactively labelled substances (see Chapter 12, Thin-Layer Radiochromatography). 

For this in situ identification method especially FAB (Fast Atom Bombardment), Liquid SIMS (Secondary-Ion MS), or laser desorption are employed as ionization techniques (49,50). The analytes are sputtered from the TLC foil (Fig. 26 (51)), or the TLC plate is placed on a movable table. More details are described in Chapter 9, Thin Layer Chromatography Coupled with Mass Spectrometry. 

Thin-Layer Chromatography Coupled with Mass Spectrometry... 

This reaction is run under the same conditions as described earlier and the products isolated by preparative thin-layer chromatography. The products should be analyzed for P content (which would be primarily monoacylphos-phatidylcholine and unreacted sn-l diacylphosphatidylcholine) and for optical activity. Whereas the starting rac-diacylphosphatidylcholine would exhibit no optical activity, each of the above products of the reaction should have optical activity. The liberated free fatty acid can be converted to a methyl ester form and examined by gas-liquid chromatography coupled with mass spectrometry (GC-MS). 

Methyl Esters. These long-chain acyl esters are subjected to thin-layer chromatography, colorimetric analysis, and gas-liquid chromatography, coupled with mass spectrometry, as described in Chapter 4. These assays will provide information on the ester/P molar ratio (based on starting phosphate value it should be 2.0) and on the composition and relative distribution of fatty acyl residues. 

Methyl Esters. This fraction can be examined first by its behavior on unidimensional thin-layer chromatography. In a solvent system of petroleum ether (30-60°)-diethyl ether-glacial acetic acid (90 10 1, v/v) and using silica gel G (250 p-m) plates, there was only a single spot at Rf 0.65-0.67. This compared exactly with a standard synthetic methyl palmitate. As described in Chapter 4, the chemical nature of the methyl esters can be obtained by analysis on gas-liquid chromatography coupled with mass spectrometry. 

Kuwayama, K., Tsujikawa, K., Miyaguchi, H., Kanamori, T., Iwata, Y.T., and Inoue, H. 2012, Rapid, simple, and highly sensitive analysis of drugs in biological samples using thin-layer chromatography coupled with matrix-assisted laser desorption/ionization mass spectrometry. Ana/. Bioanal. Chem., 402 1257-1267. 

Colorimetry, capillary electrophoresis (CE), ° mass spectrometry (MS), gas chromatography (GC), high-performance liquid chromatography (HPLC), thin-layer chromatography coupled with different detectors, and spectral techniques are the most commonly employed methods for trace environmental analysis of pesticides and also are part of regulations in monitoring the environmental pollutants. 

All previous discussion has focused on sample preparation, i.e., removal of the targeted analyte(s) from the sample matrix, isolation of the analyte(s) from other co-extracted, undesirable sample components, and transfer of the analytes into a solvent suitable for final analysis. Over the years, numerous types of analytical instruments have been employed for this final analysis step as noted in the preceding text and Tables 3 and 4. Overall, GC and LC are the most often used analytical techniques, and modern GC and LC instrumentation coupled with mass spectrometry (MS) and tandem mass spectrometry (MS/MS) detection systems are currently the analytical techniques of choice. Methods relying on spectrophotometric detection and thin-layer chromatography (TLC) are now rarely employed, except perhaps for qualitative purposes. 

Although the history of thin-layer chromatography (TLC) dates back to the analysis of plant tinctures on aluminum oxide layers with methanol mobile phase by Ismailov and Shraiber in 1938 as chronicled by Sherma and Morlock in a published chronology [1], the first report on TLC coupled with mass spectrometry (MS) was not until 1977 by Issaq [2], He eluted separated zones on a layer using the CAMAG Eluchrom instrument, designed and described in the literature in 1975 [1], and eluates were introduced into a mass spectrometer through a Pyrex inlet probe. 

Luftman, H. 2011, Thin layer chromatography (TLC) Online and offline coupling with mass spectrometry, GIT Lab. J., 5-6 37-39. 

The on-line principle has also been extended into the field of detection (Fig. 8). Thus, it is now possible to record FTIR [27-31] and Raman spectra in situ [32, 33], and there have been considerable advances in the on-line coupling of thin-layer chromatography with mass spectrometry. Here it has been, above all, the research groups of Wilson [34-36] and Busch [37-40] that have made the necessary instrumental and methodological advances, so that TLC must no longer be viewed as merely a clean-up method. Rather it forms the essential central point for all these on-line coupling techniques. 

LC-MS/MS Liquid chromatography coupled with tandem mass spectrometry LC-NMR Liquid chromatography coupled with nuclear magnetic resonance TLC Thin-layer chromatography... 

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