Thin layer chromatography , with infrared

Bouffard, S. P., Katon, J. E., Sommer, A. J. Danielson, N. D. (1994) Development of microchannel thin layer chromatography with infrared microspectroscopic detection. Analytical chemistry 66, 1937-1940. 

A system that combines gas- and thin-layer chromatography with infrared spectroscopy has been devised (Siewierski and Helrich, 1967) for the separation, quantitation, and tentative identification of DDT and twelve of its possible reaction products (metabolites and degradation products). 

Combination of Thin-Layer Chromatography with Infrared Spectroscopy... 

The conventional approach to solvent extraction is the batch method. Early work with this method was hampered by the low concentration of the compounds present and the relative insensitivity of the methods of characterization. Thus lipids and hydrocarbons have been separated from seawater by extraction with petroleum ether and ethyl acetate. The fractionation techniques include column and thin-layer chromatography with final characterisation by thin-layer chromatography, infrared, and ultra-violet spectroscopy and gas chromatography. Of these techniques, only gas chromatography is really useful at levels of organic matter present in seawater. With techniques available today such as glass capillary gas chromatography and mass spectrometry, much more information could be extracted from such samples [20]. 

Stahlmann, S. Kovar, K.-A. Analysis of impurities by high performance thin layer chromatography with fourier transform infrared spectroscopy and UV absorbance detection in situ measurement chlordiazepoxide in bulk powder and its tablets. J. Chromatogr. A 1998, 813, 145-152. 

Collection of large water samples ( 40 1) filtration on 0.45-/tm Millipore extraction at pH 3 with petroleum ether and ethyl acetate, fractionation of lipid extracts by silicic acid column chromatography (LC), thin-layer chromatography (TLC), infrared spectrophotometry (IR), gas— liquid chromatography (GLC) Gulf of Mexico (coastal, surface waters) and Pacific, from 8 to 2780 m depth dissolved paraffinic hydrocarbons 820-950 Mg 1 identification of Cio, C] 2, Ci4, C] 6 and Cj g paraffins Jeffrey et al. (1964)... 

Mass spectrometers were often the last portion of an analytical sequence that included thin-layer chromatography (TLC), infrared (IR), UV, and nuclear magnetic resonance (NMR). In synthetic chanistry MS was frequently used only to obtain accurate mass values because journals required such data. Open access allows mass spectrometry to be moved to the front of the analytical chain with rapid determination of the molecular masses of analytes. 

Dytkiewitz, E., Morlock, G.E. (2008) Analytical strategy for rapid identification and quantification of Inbricant additives in mineral oil by high-performance thin-layer chromatography with UV absorption and flnorescence detection combined with mass spectrometry and infrared spectroscopy. Journal of AO AC International, 91, 1237-1243. 

Recently, using glass micro structures for electroosmotically driven liquid chromatography was reported [48], as well as using multichannel array thin-layer chromatography with diffuse reflectance infrared spectroscopy detection [49]. Open-tubular liquid chromatography integrated onto silicon has been successfiil [50]. 

Finally, the techniques of nmr, infrared spectroscopy, and thin-layer chromatography also can be used to assay maleic anhydride (172). The individual anhydrides may be analyzed by gas chromatography (173,174). The isomeric acids can be determined by polarography (175), thermal analysis (176), paper and thin-layer chromatographies (177), and nonaqueous titrations with an alkaU (178). Maleic and fumaric acids may be separated by both gel filtration (179) and ion-exchange techniques (180). 

Figures 2 through 9 are infrared spectra of fractions collected from partition columns, gas chromatography, thin-layer chromatography, or a combination of these separation techniques. Figure 10 is the infrared spectrum of a compound isolated by gas chromatography after hydrolysis of a pyrethrum concentrate. In this case the compound is a long-chain ester. All the infrared spectra were made with a Perkin-Elmer Model 221 instrument. The following operating parameters were used. A liquid demountable cell with a 0.01-mm path length was employed.

Reference substances can be used for confirmation of identity of the substance by, e.g. infrared spectrophotometry where the spectrum of the substance to be examined must be concordant with the spectrum of the GRS, or by thin layer chromatography where the migration and appearance of the spots of both the substance to be examined and the GRS are the same, or by liquid chromatography where the retention time of both the substance to be examined and the GRS are the same. 

Infrared spectra were obtained with a Perkin-Elmer 1800 and a Nicolet Magna-IR 750 FTIR spectrophotometer, and the absorption frequencies are reported in wave numbers (cm4). NMR spectra were obtained with BZH-300 and CA-F-300 Bruker FTNMR 300 MHz spectrometers. Chloroform-d was used as solvent, and all chemical shifts are reported in parts per million downfield (positive) of the standard. H-NMR and 13C-NMR chemical shifts are reported relative to internal tetramethylsilane, while 19F-NMR chemical shifts are reported relative to internal fluorotrichloromethane, Rf values were obtained from silica gel thin-layer chromatography developed with a mixture of 1.5 mL methylene chloride and three drops of acetone. The number of hydrate water molecules was calculated from the integration of H-NMR spectra. 

AHLs can be tentatively identified by comparison of the unknown with synthetic AHL standards after Thin Layer Chromatography (TLC) in which the plates are overlaid with agar containing one of the AHL biosensors described above [37,39,44,45]. However, for the unequivocal identification of AHLs the use of more powerful methods such as LC-mass spectrometry, nuclear magnetic resonance and infrared spectroscopy as described below are required. 

The relative amounts of the products depend on irradiation time, and the formation of the bis (triphenyl phosphite) chromium complex may be almost completely avoided by following the reaction with thin layer chromatography. The diastereoisomers are air stable and reasonably soluble in most organic solvents. Their infrared spectra exhibit a metal carbonyl band at 1925 cm 1 (i>co ester at 1729 cm"1) and a metal thiocarbonyl band at 1925 cm"1 (CH2C12 solution). The NMR spectra. I 5ch3 at 1.87 ppm 5co3CH3 at 3.77 ppm II 6ch3 at 1.77... 

The reaction can be conveniently monitored in the infrared by observing the decrease in the 0=N stretching absorption at 1660 cm. 1 or by thin-layer chromatography [silica, developed with hexane-ethyl acetate (9 1) or (4 1)]. 

Qual and quan identification of expls is often fraught with difficulty owing to the inherent thermal instability of the compds which limits the use of vapor phase analytical techniques. If the expl is present in reasonably pure and coned form, infrared spectroscopy is suitable. Many times, especially if the expl is present in trace amts (mictogram quantities) ox if it is diluted with fillers (as in proplnts), separation and conen prior to identification are required. The earlier method, thin layer chromatography,... 

About 10 g of VLB (vincaleucoblastine or simply vinblastine) sulfate were converted by standard procedures to VLB free base. The free base, obtained as a residue after evaporation of the dried ethereal solvent, was dissolved in about 200 ml of anhydrous methanol. Anhydrous liquid ammonia (300 ml) was added, and the reaction mixture sealed and maintained at about 100°C for 60 hours. The reaction vessel was opened, and the contents removed and evaporated to dryness in vacuo. The resulting residue, containing 4-desacetyI VLB C-3 carboxamide, as shown by thin layer chromatography, were combined and the solvent evaporated therefrom in vacuo, yielding asa residue purified 4-desacetyl VLB C-3 carboxamide free base. The NMR and IR spectra of the solid free base confirmed the structure indicated. The free base showed a band in the infrared at 1,687 cm-1, characteristic of the amide function. The molecular weight of the free base determined by mass spectroscopy was 753 which is in agreement with theoretical value calculated for C43H55N5O7. 

Semenov et al. [8] determined small amounts of petroleum products in chloroform extracts of non saline water by extracting the sample (200-500mL) followed by thin layer chromatography on alumina. He developed the chromatogram with light petroleum-carbon tetrachloride-acetic acid (35 155 1), and examined the plate in ultraviolet radiation the petroleum products exhibit three zones (pale blue, yellow and brown). Each zone is then extracted with chloroform, the fluorescence of the extracts measured and the results referred to a calibration graph. The sensitivity is O.lmg L. The infrared and fluorescence spectra of the zone obtained with various petroleum products are discussed. 

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