Mass spectrometer-coupled

Just as with anthocyanin analysis, the advent of HPLC/mass spectrometer coupling made it possible to avoid acid hydrolysis for flavonoid identification. Maata... 

The advent of ultrafast pump-probe laser techniques62 and their marriage with the TOF method also enables study of internal ion-molecule reactions in clus-ters.21,63-69 The apparatus used in our experiments is a reflectron TOF mass spectrometer coupled with a femtosecond laser system. An overview of the laser system is shown in Figure 4. Femtosecond laser pulses are generated by a colliding pulse mode-locked (CPM) ring dye laser. The cavity consists of a gain jet, a... 

FIGURE 10.20 An illustration of a mass spectrometer coupled to an inductively coupled plasma instrument. 

There are five major components of a mass spectrometer coupled to a GC. They are, vacuum system, ion source, mass filter, detector, and data system. 

The development of lasers has opened up several new techniques for monitoring pollutants in the atmosphere. Sensitivities down to the parts-per-billion range are claimed, and continuous monitoring is possible. The photoionization mass spectrometer has been developed as a sensitive detector for fi radicals in the gas phase. A high-resolution mass spectrometer coupled to a computer is capable of detecting up to 300 compounds in air, both in particulate form and in the gas phase. 

The analysis is carried out on a Micromass Quattro II tandem mass spectrometer, coupled to a Hewlett Packard HP 1100 HPLC system. All other laboratory equipment is standard equipment,with exception of a Centrivap vacuum concentrator (Lab-con ). 

Triple-quadrupole mass spectrometer coupled with an electrospray ionisation (ESI) source. 

Complex mixtures are often analysed by hyphenated techniques, in which a separation method is interfaced with a mass spectrometer. Coupling of a gas chromatograph to a mass spectrometer (GC/MS) is simple the chromatographic capillary column is directly inserted into the ionisation chamber. Compounds eluting from the column in a gaseous state are introduced into the ion source and analysed in the order in which they exit the CG column. The vacuum system of the mass... 

Nassar, A. E. (2003). Online hydrogen-deuterium exchange and a tandem-quadrupole time-of-flight mass spectrometer coupled with liquid chromatography for metabolite identification in drug metabolism. J. Chromatogr. Sci. 41 398-404. 

An ESI mass spectrometer coupled online to a microreactor was used to intercept the catalytically active cationic intermediates of the Ziegler-Natta polymerization of ethylene with the homogeneous catalyst system [Cp2Zr(Me)Cl]-MAO (MAO = methylaluminoxane). For the first time these intermediates were studied directly in the solution and their catalytic activity proved.60... 

Arpino, P. J. Guiochon, G. Krien, R Devant, G. 1979. Optimization of the instrumental parameters of a combined liquid chromatograph-mass spectrometer, coupled by an interface for direct liquid introduction. . /. Chromatogr., 185,529-547. 

Polypeptides of up to approximately 25 residues can be sequenced by the technique of mass spectrometry (MS), which involves an ionization technique called fast atom bombardment (FAB) in concert with a tandem mass spectrometer (two mass spectrometers coupled in series). The sequence of the polypeptide can be obtained from the molecular masses of the various fragments produced in the ionization stage in only a few minutes compared to the hour required for just one cycle of Edman degradation. In addition, mass spectrometry can be used to sequence several polypeptides in a mixture, alleviating the need to completely... 

To analyse the solvent extracts a lOpL aliquot of the concentrated extract was injected into a Finnigan 4000 gas chromatograph-mass spectrometer coupled to a 6110 data system. A 3% OV-17 provided the best separation of the detectable PAHs. Quantitative estimations of the detectable O-PAHs in Ottawa drinking water were obtained by comparison of the areas of the two characteristic ion peaks (Tablesl6.2 and 16.3) in the mass chromatograms of the reference standard and the field sample, respectively. No corrections were made for incomplete recovery. Of the 50 PAHs in the standard used by Benoit et al. [119], 38 are detected in at least one of the drinking water samples tested. 

Quadrupole mass spectrometers coupled with LC make up a large part of the market. 

First mass spectrometers coupled with data processing units. 

In some experiments a mass spectrometer coupled to an ion source was used for the identification of the released molecules H2 discharges and carbon-rich materials generated methane derivatives CH4 ,. Hydrogen reactions... 

Modica and LaGraff (14) investigated the kinetics of CHF decomposition by a mass spectrometer coupled to a shock tube. They investigated the pressure dependence of the rate and concluded that at the hgh pressure limit E = 58.4 2.2 kcal. 

Mass spectrometers coupled with gas and liquid chromatographs (GC-MS and LC-MS) result m versatile analytical instruments that combine the resolving power of the chromatographs with the exquisite specificity and sensitivity of a mass spectrometer. Such instruments are powerful analytical tools that are used by clinical labs to identify and quantify organic analytes. They provide structural and quantitative information in real time on individual analytes as they elute from a chromatographic column. These coupled techniques are very sensitive and only nanogram or picogram quantities of an analyte are required for analysis. Specific apphcations of these coupled instruments are found in Chapters 33 and 34. 

The TG-MS assembly consisted of a double-focusing DuPont 21-491 Mass spectrometer coupled through a single-stage glass jet separator to a DuPont 951 Thermal Gravimetric Analyzer which was attached to a DuPont 990 Thermal Analyzer Console. 

Figure 1 shows a magnetic-type sector field mass spectrometer coupled with a Knudsen cell. The most important part of the instrument is the Knudsen cell. It can be heated up to temperatures above 2500 K. The temperatures are measured with an optical pyrometer or a thermocouple. There would be thermodynamic equilibrium in the Knudsen cell if it were closed. However, real Knudsen cells have an effusion orifice (typical diameter 0.1 to 1 mm) through which a small fraction of the molecules effuse without practically disturbing the equilibrium in the cell. A molecular beam representing the equilibrium vapor in... 

Ding, L., Sudakov, M., Brancia, F.L., Giles, R., and Kumashiro, S. (2004). A digital ion trap mass spectrometer coupled with atmospheric pressure ion source, J Mass Spectrom., 39,471 148. 

A time-of-flight mass spectrometer coupled to a shock tube was used to record the change in mass spectral peak heights as a function of reaction time [123]. Mass spectra of the gas flowing from the reflected shock zone into the ion source were taken at 25 psec intervals. 

Besides the universal detector systems, for example electron capture, flame ionisation and thermal conductivity usually coupled with gas chromatographic columns, various other detectors are now being used to provide specific information. For example, the gas chromatograph/mass spectrometer couple has been used for structure elucidation of the separated fractions. The mechanics of this hybrid technique have been described by Message (1984). Other techniques used to detect the metal and/or metalloid constituents include inductively coupled plasma spectrometry and atomic absorption spectrometry. Ebdon et al. (1986) have reviewed this mode of application. The type and mode of combination of the detectors depend on the ingenuity of the investigator. Krull and Driscoll (1984) have reviewed the use of multiple detectors in gas chromatography. 

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