Trimethylsilyl ethers of methylated gas-liquid chromatography

Gas — liquid chromatography has proved a useful analytical technique in carbohydrate chemistry, particularly for methyl ethers and acetic esters. By forming trimethylsilyl ethers of relatively nonvolatile sulfonates of sugars, gas — liquid chromatography can be performed. 

T3. Tanida, N., Hisaka, Y., and Shimoyama, T., Evaluation of polyethylene glycol-HT as a stationary phase for capillary column gas-liquid chromatography of trimethylsilyl ethers ofbile add methyl esters. J. Chromatogr. 240, 75-79 (1982). 

The separation of bile acids by gas-liquid chromatography is determined by the choice of stationary phase and bile acid derivative. Data that permit the selection of stationary phase and bile acid derivative to suit most separation problems are shown in Tables XII-XIV. As in the original papers relative retention times have been used in the tables instead of the more acceptable retention index (112) which permits better interlaboratory comparisons. Relative retention times are subject to variation, mainly due to temperature differences and, to a lesser extent, to differences in column preparation. In our experience the temperature-dependence is most pronounced with trimethylsilyl ether derivatives on Hi-Eff-8B (cyclohexanedimethanol succinate) columns. Temperature differences do not affect relative retention times on QF-1 (a trifluoropropyl, methyl siloxane) to the same extent. 

Samples (2 mg) of the proteins were methanolyzed with methanol-1.5 M HCl and N-acetylated with acetic anhydride (19). The determination of methyl glycosides as their trimethylsilyl ethers was carried out by gas-liquid chromatography (20). 

Total extracts and/or liquid chromatographic subfractions are then analyzed by capillary colnmn gas chromatography nsing a flame ionization detector. Except for hydrocarbon fractions, derivatization is commonly applied to render polar lipids more volatile in order to reduce gas chromatographic retention times and to improve peak shape at the detector. Carboxylic acids are usually transformed into their methyl esters, and hydroxyl or amine gronps into their trimethylsilyl ether derivatives. Alternatively, both acid and hydroxyl groups can be silylated. Acetate formation is another common derivatization method. A variety of derivatization reagents are conunercially available for this purpose. 

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