Gas-liquid chromatography and mass

GABA, heterocyclic analogues, 22 (1985) 67 GABAa receptor ligands, 36 (1999) 169 Gas-liquid chromatography and mass spectrometry, 12 (1975) 1 Gastric H /K -ATPase inhibitors, 31 (1994) 233... 

GABA, heterocyclic analogues, 22 (1985) 67 Gas-liquid chromatography and mass spectrometry, 12 (1975) 1... 

Exhaustive chlorination of thianthrene yields a mixture of polychloro-derivatives, the main component being 2,3,7,8-tetrachlorothianthrene (77USP3989715). In a survey, authors looking for dioxinlike activity in sediment from a sanitary sewer near a chemical factory detected tetrachlo-rothianthrene using gas-liquid chromatography and mass spectrometry (85MI4). 

The formation of -isomers during acylation of the unsubstituted thienothiophenes 1 and 2 was reported first in 1972 by Bugge, who showed by gas-liquid chromatography and mass spectrometry that thienothiophenes 1 and 2 with acetic anhydride and SnCl4 in dichloroethane at 25° affords the 2-acetyl derivatives (80% yields), containing up to 1% of 3-acetylthieno[2,3-6]thiophene and 0.8% of 3-acetylthieno[3,2-h]thiophene. 

DC046 Kolattukudy, P. E., K. Kronman, and A. ]. Poulose. Determination of structure and composition of suberin from the roots of carrot, parsnip, rutabaga, turnip, red beet and sweet potato by combined gas-liquid chromatography and mass spectrometry. Plant Physiol 1975 55 567. 

Deliberate partial trimethylsilylation may be used as a means of distinguishing between various monosaccharides,199 and the nature of minor components formed on trimethylsilylation has been studied by mass spectrometry. Trimethylsilylation has been used in the separation of deuterated monosaccharides,200-203 and such deuterated trimethylsilyl derivatives as penta-0-(trimethyl-dliquid chromatography and mass spectrometry.143... 

Reineccius, G. A., Kavanagh, T. E. and Keeney, R G. 1970. Identification and quantitation of free neutral carbohydrates in milk products by gas-liquid chromatography and mass spectrometry. J. Dairy Sci. 53, 1018-1022. 

B. A. Dmitriev, L. V. Backinowsky, O. S. Chizhov, B. M. Zolotarev, and N. K. Kochetkov, Gas-liquid chromatography and mass spectrometry of aldononitrile acetates and partially methylated aldononitrile acetates, Carbohydr. Res., 19 (1971) 432 135. 

Harvey, D.J., Comparison of fourteen substituted silyl derivatives for the characterization of alcohols, steroids and cannabinoids by combined gas-liquid chromatography and mass spectrometry, J. Chromatogr., 147, 291, 1978. 

Woodward, M. D., Corcuera, L. J., Schnoes, H. K., Helgeson, J. P., and Upper, C. D. 1979. Identification of 1,4-Benzoxazin-3-ones in maize extracts by gas-liquid chromatography and mass spectrometry. Plant Physiol. 63, 9-13... 

Morita, N., Hayashi, K., Takagi, M., and Miyano, K. (1983). Gas-liquid chromatography and mass spectrometry of quinoxalines derived from various homoglucans by alkaline o-phenyl-enediamine method. Agric. Biol. Chem. 47 757-763. 

The most effective way to analyze quantitatively the composition of the purified methyl esters is by gas-liquid chromatography, using a flame ionization detector. As an alternative, a combination of gas-liquid chromatography and mass spectrometry can provide a wealth of information on composition and structure. The mass of material required for this type of separation depends in part on the size and type of chromatography column and the type of mass spectrometer. Amounts of material as low as 5 xg can be analyzed by this combined technique. 

Methyl Esters. These esters can be isolated and purified by thin-layer chromatography on silica gel G with a solvent system of petroleum ether (b.p. 30-60°)-diethyl ether (80 20, v/v). Usually these esters exhibit an /Rvalue in the range of 0.80-0.85. Their characterization can be achieved in a manner similar to that described in Chapter 4. Thus, a combination of gas-liquid chromatography and mass spectrometry will afford a detailed insight into the structure and composition of these long-chain fatty acid esters. 

Indirect indicators of vitamin B12 deficiency include measurements of the metabolites homocysteine and methylmalonic acid (MMA) in serum and MMA in urine (see the Biochemical Perspectives section). Whereas the serum homocysteine concentration increases during folate or vitamin B12 deficiencies, the serum and urine MMA concentrations increase only in vitamin B12 deficiency. Therefore, MMA determinations can be used to differentiate vitamin B12 deficiency from folate deficiency. The normal concentration of MMA in serum ranges from 0.08 to 0.28 pmol/L. MMA is quantified using gas-liquid chromatography and mass spectrometry. Elevated concentrations of MMA and homocysteine in serum may precede the development of hematological abnormalities and reductions in serum vitamin B12 concentrations. One should be aware that other conditions, including renal in sufficiency and inborn errors of metabolism, can also result in elevated serum levels of MMA. 

C. A. Stortz, M. C. Matulewicz, and A. S. Cerezo, Separation and identification of O-acetyl-O-methyl-galactononitriles by gas-liquid chromatography and mass spectrometry, Carbohydr. Res., Ill (1982) 31-39. 

H. Bjomdal, C. G. Hellerqvist, B. Lindberg, and S. Svensson, Gas-liquid chromatography and mass spectrometry in methy lation analysis of polysaccharides, Angew. Chem., Int. Ed. Engl., 9 (1970) 610-619. 

All of the theories that have just been mentioned were put forward at a time when few experimental details had been established for pyrolyses in the gas phase. During the past few years powerful techniques, particularly those of gas-liquid chromatography and mass spectrometry, have been developed, so that it is now possible to study the kinetics of formation of the minor products. 

L15. Lloyd, T., Markey, S., and Weiner, N., Identification of 2-amino-4-hydroxy substituted pteri-dines by gas-liquid chromatography and mass spectrometry. Anal. Biochem. 42, 108-112 (1971). 

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