Chromatography GC mass spectrometry

FIG. 13 Carbon number distribution of alkanemonosulfonates by pyrolysis gas chromatography (GC)/mass spectrometry (paraffin raw material by GC). 

In the past decade, eight inherited disorders have been linked to specific enzyme defects in the isoprenoid/cholesterol biosynthetic pathway after the finding of abnormally increased levels of intermediate metabolites in tissues and/or body fluids of patients (Table 5.1.1) [7, 9, 10]. Two of these disorders are due to a defect of the enzyme mevalonate kinase, and in principle affect the synthesis of all isoprenoids (Fig. 5.1.1) [5]. The hallmark of these two disorders is the accumulation of mevalonic acid in body fluids and tissues, which can be detected by organic acid analysis, or preferably, by stable-isotope dilution gas chromatography (GC)-mass spectrometry (GC-MS) [2]. Confirmative diagnostic possibilities include direct measurement of mevalonate kinase activities in white blood cells or primary skin fibroblasts [3] from patients, and/or molecular analysis of the MVK gene [8]. 

While the clinical use of MS/MS of hormonal steroids is new, metabolite analysis by gas chromatography (GC)-mass spectrometry (MS) has been available for 40 years, since few immunoassays were developed for urinary analytes. Profile analysis is a very powerful technique and it must be recognized that with few exceptions, all disorders of steroid synthesis and metabolism first had their metabolome defined... 

Silver ion TLC offers an effective means of fractionation of Upid mixtures into distinct fractions differing in the number of double bonds. It is often used to simplify the further examination with gas chromatography, GC-mass spectrometry, Fourier transform infrared, and so forth. Ag TLC serves also as an enrichment procedure for minor components and allows for more accurate estimation of their content and identity. Quantitative procedures have been developed for the determination of fatty acids and triacylglycerols by using Ag TLC and densitometry. 

Gas chromatography, GC mass spectrometry, MS hydride generation, HG atomic absorption spectrometry, AAS inductively coupled plasma, ICP solid phase microextraction, SPME fluorine-induced chemiluminescence, FIG. 

The complex mixture of microbial cellular and extracellular components is an appealing target for chemotaxonomic analysis by gas chromatography (GC), mass spectrometry (MS), or the combination of the two techniques (GC/MS). Such instrumental methods focus on chemical structures present in a sample and are not dependent, as are biological tests, on the microorganism being viable. Additionally, since only microgram amounts of sample are required, instrumental methods offer enhanced sensitivity. 

Capillary column gas chromatography (GC)/mass spectrometry (MS) has also been used to achieve more difficult separations and to perform the structural analysis of molecules, and laboratory automation technologies, including robotics, have become a powerful trend in both analytical chemistry and small molecule synthesis. On the other hand, liquid chromatography (LC)/MS is more suitable for biomedical applications than GC/MS because of the heat sensitivity exhibited by almost all biomolecules. More recent advances in protein studies have resulted from combining various mass spectrometers with a variety of LC methods, and improvements in the sensitivity of nuclear magnetic resonance spectroscopy (NMR) now allow direct connection of this powerful methodology with LC. Finally, the online purification of biomolecules by LC has been achieved with the development of chip electrophoresis (microfluidics). 

The human nose neither tries to break the aroma into different constituents nor to quantify the constituents. Unfortunately, there is no effective instrumental analysis to replace the human sense. Analytical instruments such as gas chromatography (GC)/mass spectrometry (MS), high pressure liquid chromatography (HPLC) and NMR spectroscopy could be used to monitor the particular compounds present in a variety of samples. However, their use is... 

A number of analytical methods [66, 67] involving pyrolysis of polymers have been reported in the literature. Michal and co-workers [68] developed a method using direct gas chromatography (GC)-mass spectrometry (MS) for their study of the combustion of polyethylene (PE) and PP. Morikawa [69] used GC to determine polycyclic aromatic hydrocarbons in the combustion of polymers. Liao and Browner [70] also described a method for the determination of polycyclic aromatic hydrocarbons. Many other workers have studied soot and smoke formation and their mechanisms in the combustion of polymers. Generally in these studies, relatively simple and specific methods were used, which were appropriate for the intended tasks. However, these methods are not suitable for complete analysis of the very complex smoke particulates resulting from combustion of many polymers. Most methods have been developed either for volatile compounds of low molecular weight or for polycyclic aromatic hydrocarbons. Joseph and Browner [71] developed a method that can be used to... 

The analysis of cyclopropane acids was reviewed by Minnikin (1978) and by Christie (1970), who also covered cyclopropene acids. Subsequently, Sebedio and Grandgirard (1989) discussed naturally occuring cyclic acids and cyclic acids formed in heated vegetable oils. Cyclic acids were the subject of a recent review (Le Quere and Sebedio, 1996). Useful information on gas chromatography (GC), mass spectrometry (MS) and high-pressure liquid chromatography (HPLC) of cyclic fatty acids can be found in books by Christie (1987, 1989). In the present chapter the aim is to concentrate on the more recent literature and those publications considered to be particularly... 

As a result of the development of special bonded phases, carbohydrates or their derivatives are usually separated by hquid chromatography (LC). However, certain carbohydrate samples are stiU analyzed by gas chromatography (GC) due to the inherent high efficiencies obtainable from the technique and to the associated short elution times. In addition, gas chromatography (GC)/ mass spectrometry (MS) is a particularly powerful analytical technique for carbohydrates, especially for their identification. As a consequence, appropriate derivatives must be formed to render them sufficiently volatile but stiU easily recognizable from their mass spectra. 

The extraction process, collection of dmg material, plant parts, age of the plant, and geographical and climatic conditions affect chemical profile and stereochemistry of the essential oil products [5, 6]. Most of the commercialized essential oils are analyzed by gas chromatography (GC), mass spectrometry (MS), or a combination of GC-MS technique [7]. 

The technique of choice for the analysis of VOCs in water is gas chromatography (GC). Mass spectrometry is also applied in multicomponent analysis but has drawbacks. Because of the low concentrations in water (from ng/L to fig/L) and the established guideline values, extraction and preconcentration steps are indispensable and essential before the analysis. Two separate steps can be distinguished in the analytical scheme. 

Analytical Chemistry 71, No.2, 15th Jan.1999, p.468-75 IDENTIFICATION AND DETERMINATION OF CROSSLINKERS IN CROSSLINKED POLYVINYLPYRROLIDONE(PVP) BY PYROLYSIS-GAS CHROMATOGRAPHY(GC)/ MASS SPECTROMETRY(MS)... 

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