Gas chromatography coupled with mass

GC-MS gas chromatography coupled with mass spectrometry HDL heavy-duty liquid or laundry liquid... 

For human studies, the choice of stable isotopes is limited because radioisotopes are associated with ionization radiation and thus with some potential harmful effects for humans. Studying the bioavailability of compounds labeled with stable isotopes requires complex techniques such as gas chromatography coupled with mass spectrometry (GC-MS), liquid chromatography coupled with MS (LC-MS), and atmo-... 

Microbes of differing physiologic types, acting in consortia, appear to be more destructive than monocultures. Methods for examining consortia are based on the detection of lipid biomarkers that are characteristic for different classes of microbes. These can be analyzed by gas chromatography coupled with mass spectrometry [512]. 

Gas chromatography coupled with mass spectrometric detection has also been applied to the detection of... 

Stirring was initiated, and the autoclave was heated to 400°C which required 90 minutes for E10 and 100 minutes for El9. The temperature was maintained at 400°C for 1 hour, then lowered to room temperature. The cooling duration to 300°C was 5 minutes for E10 and 40 minutes for El9. Stirring was terminated at room temperature. Gaseous products were removed for analysis by gas chromatography coupled with mass spectrometry (GC-MS). The reaction products were distilled at reduced pressure to remove the spent donor solvent mixture, and the remaining coal products were solvent fractionated. 

Halket and Lisboa (25) examined several Vitamin D derivatives by capillary gas chromatography coupled with mass spectrometry. This technique offered the advantages of great sensitivity and separating power. Retention times and fragmentation patterns for ergocalciferol, cholecalciferol and calcitriol were reported. 

Much less work has been focused on the effect of polymer structure on the resist performance in these systems. This paper will describe and evaluate the chemistry and resist performance of several systems based on three matrix polymers poly(4-t-butoxycarbonyloxy-a-methylstyrene) (TBMS) (12), poly(4-t-butoxycarbonyloxystyrene-sulfone) (TBSS) (13) and TBS (14) when used in conjunction with the dinitrobenzyl tosylate (Ts), triphenylsulfonium hexafluoroarsenate (As) and triphenylsulfonium triflate (Tf) acid generators. Gas chromatography coupled with mass spectroscopy (GC/MS) has been used to study the detailed chemical reactions of these systems in both solution and the solid-state. These results are used to understand the lithographic performance of several systems. 

Stage II Sequential analytical techniques Gas chromatography Gas chromatography coupled with mass spectrometry, multidimensional gas chromatography... 

Brede, C., Skjevrak, I. and Herikstad, H. (2003). Determination of primary aromatic amines in water food simulant using solid-phase analytical derivatization followed by gas chromatography coupled with mass spectrometry, J. Chrom. A, 983, 35-42. 

Samples are analysed using gas chromatography coupled with mass spectrometry (GC-MS). This instmment separates the organic hydrocarbons in the extract with a very high resolution fused silica capillary column prior to mass spectrometric detection. Acquisition parameters have been customized to detect the target list of 162 hydrocarbons with the sensitivity required to obtain 1 part-per-trillion reporting limits which represents an innovation in these analytics. 

Following separation on conventional gas chromatographic columns, electron-capture detector (402) has been used for the determination of the hydroxy metabolite of dimetridazole in swine muscle with good sensitivity and specificity. To confirm the presence of lasalocid residues in bovine liver, gas chromatography coupled with mass spectrometry via a chemical ionization interface (387) has been successfully applied. 

As already mentioned, it is the volatile constituents that serve to identify fruit type and variety. Broadly speaking, qualitative analysis will identify the principal substances present in the volatiles fraction as representative of a particular fruit type, but it is the relative proportions of these substances that will reflect the variety. Alcohols, volatile acids, esters, carbonyl compounds, and low-boiling hydrocarbons are the principal groups represented. Analysis by GC-MS (gas chromatography coupled with mass spectroscopy) can be used to provide quantification and identification of the various constituents. 

The best method for determining pentachlorophenol is conversion into the methyl ether followed by analysis using gas chromatography with an electron-capture detector, or gas chromatography coupled with mass spectrometry [2], Both of these methods require an extensive amount of pretreatment and highly-trained personnel f or the operation of the equipment. 

Following the first studies of J.J. Thomson (1912), mass spectrometry has undergone countless improvements. Since 1958, gas chromatography coupled with mass spectrometry has revolutionized the analysis of volatile compounds. Another revolution occurred in the 1980s when the technique became available for the study of non-volatile compounds such as peptides, oligosaccharides, phospholipids, bile salts, etc. From the discoveries of electrospray and matrix-assisted laser desorption in the late 1980s, compounds with molecular masses exceeding several hundred thousands of daltons, such as synthetic polymers, proteins, gly-cans and polynucleotides, have been analysed by mass spectrometry. 

Like the hydrolysis methods, many extraction procedures have been described. Table 3 presents the various procedures and the compounds used as IS. With the development of the technology and the introduction of gas chromatography coupled with mass spectrometry (GC/MS), deuterated IS have been used for the quantification of cannabis in hair. Presently, this technique represents the state of the art. Most authors use liquid-liquid extraction only Moeller and Moeller et al. - have reported solid-phase extraction (SPE) procedures. 

When the reaction mixture is kept for a prolonged period of time without terminating, the formation of cyclic oligomers can be detected by gas chromatography coupled with mass spectrometry and their concentration increases with time, as shown in Table 10 [90]. The results show that... 

The basic methodologies of measuring JH titer and rates of biosynthesis will be mentioned here only briefly. JH titer is determined by either radioimmunoassay (3) or preferably by gas chromatography coupled with mass-spectrometry (4-6). Alternatively, JH biosynthesis can be determined with excised CA in vitro by the radiochemical (RCA) method (2). JH values obtained by titering reflect the equilibrium of rate of JH synthesis, its degradation and clearance from the hemolymph, its tissue uptake and excretion. The rate of de novo synthesis, as measured by the RCA method, is argued to correlate well with JH hemolymph titer (8.9). As we shall later show, the correlation of in vitro synthesis and ija vivo titers is not always maintained in L. migratoria under all experimental situations. 

The method of trace measurements used must be also taken into account. For example, volatile solvents are required for gas chromatography coupled with mass spectrometry (GC-MS) whereas nonvolatile solvents are used for high performance liquid chromatography (HPLC). Low surface tension can lead to creation of an emulsion and result in a longer time for phase separation. 

Gas chromatography coupled with mass spectrometry (GC-MS) commonly requires a derivatization step in order to enhance both the stability and amount of determined metabolites. The separated metabolites, after derivatization, are introduced to the mass spectrometer, wherein they undergo ionization and are selectively determined according to their mass-to-charge ratio (zm/z). Using GC-MS,... 

Advances in analytical techniques over the past 10 years, particulady with gas chromatography coupled with mass spectrometry, have facilitated a detailed examination of the volatile components of the micro-organic constituents of waters. Eyen though 3000 compounds have been identified and stored on computer file they represent a minor portion of organic substances which may be found in river waters, drinking-waters, and even groundwaters. 

In addition to food analysis, the environment is monitored to measure the degree of contamination that might be caused by the use of pesticides. These projects entail sampling of wild life, water sources, and soils. Wealthy countries can utilize highly sophisticated and expensive equipment, such as gas chromatography coupled with mass spectrometry, for residue determination and identification. However, since there is inter-... 

Kerogen pyrolysate components were analyzed by gas chromatography coupled with mass spectrometry (GC/MS). Approximately 10 mg of kerogen were deposited in a quartz tube and pyrolyzed in a helium stream, while the pyrolysis temperature was raised to 650°C at 200°C/s and held at the final temperature for 16s. 

Macrocyclics (starting with dimers) have been observed in every cationic ringopening system, provided the authors specifically searched for cyclic entities. In the polymerization of THF the first report indicated that macrocyclics are not formed 11 but shortly thereafter Pruckmayr corrected this view and described a series of cyclic oligomers identified by gas chromatography coupled with mass spectroscopy2,3). 

Raton, J.J., R.D. Bereman, and N.J. Glass An analytical method has been developed for naphthalene and methyl substituted naphthalenes found in mainstream cigarette smoke using gas chromatography coupled with mass spectrometry 57th Tobacco Science Research Conference, Program Booklet and Abstracts, Vol. 57, Paper No. 13, 2003, p. 25. 

The results were obtained by continuous analysis of the hydrogenation medium. The reaction was performed in a 1 I autoclave equipped with a magnetically driven stirrer at a speed of about 1000 r/m. Samples were periodically withdrawn through a decanter tube from the bottom of the reactor. The main products were analysed by gas chromatography coupled with mass spectroscopy, NMR and infrared spectroscopy. 

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