Gas chromatography coupled mass

Several papers utilizing 3 mm probe capabilities were also published that delved into the area of protein structures. Hepatocyte nuclear factor 4 was studied by a group lead by Williams.155 It is interesting to note that a 2.7 A X-ray study showed a fatty acid in the pocket of HNF4y. Gas chromatography coupled mass spectrometry (GC/MS) and 3 mm NMR studies of extracts from purified HNF4x led to the identification of mixtures of saturated and crs-monounsaturated Ci4 to Qg fatty acids. Bertini and co-workers156 utilized 3 mm probe capabilities in the determination of the solution structure of CopC, a cupredoxin-like protein involved in copper homeostasis. 

Solid-phase microextraction (SPME) was used for headspace sampling. The FFA were extracted from the headspace with PA, Car/PDMS, and CW/DVB fibers. It was examined whether addition of salt (NaCl) and decreasing the pH by addition of sulphuric acid (H SO ) increased the sensitivity. FFA were analyzed using gas chromatography coupled to mass spectrometry in selected ion monitoring. 

Reprinted from Journal of High Resolution Chromatography, 21, D. Juchelka et al., Multidimensional gas chromatography coupled on-line with isotype ratio mass specti ometry (MDGC-IRMS) progress in the analytical authentication of genuine flavor components , pp. 145-151, 1998, with peraiission from Wiley-VCH. 

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

Planas C, Caixach J, Santos FJ, et al. 1997. Occurrence of pesticides in Spanish surface waters. Analysis by high resolution gas chromatography coupled to mass spectrometry. Chemosphere 34(ll) 2393-2406. 

The data in Table I are also significant in terms of the type of analysis to determine the presence of NDMA. In all cases analysis was done using gas chromatography coupled with a Thermal Energy Analyzer, a sensitive, relatively specific nitrosamine detector (12). Further, in six of the studies, the presence of NDMA in several samples was confirmed by gas chromatography-mass spectrometry (GC-MS). The mass spectral data firmly established the presence of NDMA in the beer samples. 

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... 

Principles and Characteristics The most commonly used and widely known technique coupled to gas chromatography is mass spectroscopy. In early couplings, with packed GC columns being the major problem encountered, elimination of the carrier gas at relatively high flow-rates (25mLmin 1), resulted in a significant loss of sensitivity. With the advent of open tubular devices, the column flow could be passed directly into the mass spectrometer. GC-MS is typically... 

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. 

The production of 13CC>2 from [13C]-deca-BDE degradation was analyzed using the technique of gas chromatography coupled to mass spectrometer for isotope ratio (GC-EMRI). This technique measures the isotopic ratio 13C/12C of CO2 in the gas phase with respect to an international standard V-PDB (Vienna Pee Dee Belem-nite). This isotopic ratio is reported in 8 notation relative to an international standard per mil (%o) ... 

Meier Augenstein, W. (1999) Applied gas chromatography coupled to isotope ratio mass spectrometry. Journal of Chromatography, A 842, 351 371. 

Carrizo D, Grimalt JO (2006) Rapid and simplified method for the analysis of polychlor-onaphthalene congener distributions in environmental and human samples by gas chromatography coupled to negative ion chemical ionization mass spectrometry. J Chromatogr A 1118(2) 271-277... 

A rapid and simple method for PBDE and HBCD determinations in sediment and fish samples was used. The analytical method was based in selective pressurized liquid extraction (SPLE) [21] without further cleanup step and analysis by gas chromatography coupled to mass spectrometry (GC-MS), working with negative ion chemical ionization (NCI) [22, 23],... 

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... 

GC-CIMS Gas chromatography coupled to chemical ionization mass spectrometry... 

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. 

Mass spectrometry (MS) is probably a famhiar tool to chemistry and biology students as a technique commonly used to measure the molecular mass of a sample. Often, MS is used in tandem with other techniques for chromatic separation of the sample before mass measurement. Some common hyphenated techniques include HPLC-MS, high-pressure liquid chromatography coupled to MS GC-MS, gas chromatography coupled to MS or CE-MS, capillary electrophoresis coupled to MS. 

While the first coupling of gas chromatography and mass spectrometry had been reported in the late fifties [4] one had to wait for almost another 20 years before the direct interfacing of liquid chromatography with mass spectrometry (LC-MS) was described by Arpino et al. [5]. With the direct liquid interface (DLI) the effluent of the chromatographic column was directly introduced in the electron impact source. Contrarily to gas chromatography coupled to mass spectrometry (GC-MS), LC-MS did do not catch on as rapidly. One of the reasons was that the MS interface could only handle LC fiow rates of a few microliters per minute. Another limitation was that electron impact or chemical ionization was not suit-... 

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