Mass spectrometry

Using Mass Spectrometry for Determining Distribution by Chemical Families  [c.44]

Magnetic Deviation Mass Spectrometry  [c.47]

Qualitative Analysis by Mass Spectrometry  [c.48]

Quantitative Analysis by Mass Spectrometry  [c.48]

The resulting mass spectrometry analysis is an analysis by chemical  [c.49]

Separation of families by merely increasing the resolution evidently can not be used when the two chemical families have the same molecular formula. This is particularly true for naphthenes and olefins of the formula, C H2 , which also happen to have very similar fragmentation patterns. Resolution of these two molecular types is one of the problems not yet solved by mass spectrometry, despite the efforts of numerous laboratories motivated by the refiner s major interest in being able to make the distinction. Olefins are in fact abundantly present in the products from conversion processes.  [c.50]

Petroleum Analysis by Mass Spectrometry  [c.50]

Non-exhaustive summary of analytical methods using mass spectrometry.  [c.50]

Interest in this method has decreased since advances made in gas chromatography using high-resolution capillary columns (see article 3.3.3.) now enable complete identification by individual chemical component with equipment less expensive than mass spectrometry.  [c.51]

As the temperatures of the distillation cuts increase, the problems get more complicated to the point where preliminary separations are required that usually involve liquid phase chromatography (described earlier). This provides, among others, a saturated fraction and an aromatic fraction. Mass spectrometry is then used for each of these fractions.  [c.53]

One has seen that the number of individual components in a hydrocarbon cut increases rapidly with its boiling point. It is thereby out of the question to resolve such a cut to its individual components instead of the analysis by family given by mass spectrometry, one may prefer a distribution by type of carbon. This can be done by infrared absorption spectrometry which also has other applications in the petroleum industry. Another distribution is possible which describes a cut in tei ns of a set of structural patterns using nuclear magnetic resonance of hydrogen (or carbon) this can thus describe the average molecule in the fraction under study.  [c.56]

The spectroscopic methods, NMR and mass spectrometry for predicting cetane numbers have been established from correlations of a large number of samples. The NMR of carbon 13 or proton (see Chapter 3) can be employed. In terms of ease of operation, analysis time (15 minutes), accuracy of prediction (1.4 points average deviation from the measured number), it is  [c.220]

With regard to mass spectrometry, accuracy is not as high with an average error of 2.8 points, but on the other hand, the sample required is very small, being around 2 jl1.  [c.221]

Composition by mass spectrometry (1) (2) (3) (4) (5)  [c.225]

Fisher, I.P. and P. Fisher (1974), Analysis of high boiling petroleum streams by high resolution mass spectrometry . Talanta, Vol. 21, p. 867.  [c.455]

Ions are also used to initiate secondary ion mass spectrometry (SIMS) [ ], as described in section BI.25.3. In SIMS, the ions sputtered from the surface are measured with a mass spectrometer. SIMS provides an accurate measure of the surface composition with extremely good sensitivity. SIMS can be collected in the static mode in which the surface is only minimally disrupted, or in the dynamic mode in which material is removed so that the composition can be detemiined as a fiinction of depth below the surface. SIMS has also been used along with a shadow and blocking cone analysis as a probe of surface structure [70].  [c.310]

Chang C-C and Winograd N 1989 Shadow-cone-enhanced secondary-ion mass-spectrometry studies of Ag(110) Rhys. Rev. B 39 3467  [c.319]

The hydration of more inert ions has been studied by O labelling mass spectrometry. 0-emiched water is used, and an equilibrium between the solvent and the hydration around the central ion is first attained, after which the cation is extracted rapidly and analysed. The method essentially reveals the number of oxygen atoms that exchange slowly on the timescale of the extraction, and has been used to establish the existence of the stable [1 10304] cluster in aqueous solution.  [c.568]

Most ion-molecule techniques study reactivity at pressures below 1000 Pa however, several techniques now exist for studying reactions above this pressure range. These include time-resolved, atmospheric-pressure, mass spectrometry optical spectroscopy in a pulsed discharge ion-mobility spectrometry [108] and the turbulent flow reactor [109].  [c.813]

Mass spectrometry, the primary detection method in the above crossed beams experiments, is a particularly general means of analysing reaction products, since no knowledge of the optical spectroscopy of the products is required. On the other hand, electron impact ionization often leads to extensive fragmentation, thereby complicating identification of the primary products. Very recently, tunable VUV radiation from synclirotrons has been used to ionize scattered products from both photodissociation [22] and bimoleciilar reactions [23] other than the ionization mechanism, the instrument is similar in principle to that shown in figure A3.7.2. By choosing the VUV wavelength to lie above tire ionization potential of the product of interest but below the  [c.873]

A complementary approach to reaction dynamics centres on probing reaction products by optical spectroscopy. Optical spectroscopy often provides higher resolution on the product internal energy distribution than the measurement of translational energy distributions, but is less universally applicable than mass spectrometry as a detection scheme. If products are fonned in electronically excited states, their emission spectra (electronic chemiluminescence) can be observed, but ground-state products are more problematic. Polanyi [24] made a seminal contribution in this field by showing that vibrationally excited products in their ground electronic state could be detected by spectrally resolving their spontaneous emission in the infrared this method of infrared chemiluminescence has proved of great utility in detennining product vibrational and, less frequently, rotational distributions.  [c.873]


The basic principle behind TOP mass spectrometry [36] is tire equation for kinetic energy, ze V  [c.1351]

Harrison A G 1992 Chemical Ionization Mass Spectrometry (Boca Raton, FL Chemloal Rubber Company)  [c.1358]

Dawson P H 1976 Quadrupole Mass Spectrometry and its Applications (Amsterdam Elsevier)  [c.1358]

Mass spectrometry allows analysis by hydrocarbon family for a variety of petroleum cuts as deep as vacuum distillates since we have seen that the molecules must be vaporized. The study of vacuum residues can be conducted by a method of direct introduction which we will address only briefly because the quantitative aspects are ek r metiy difficult to master. Table 3.6 gives some examples the matrices used differ according to the distillation cut and the chemical content such as the presence or absence of olefins or sulfur.  [c.50]

Before ehding this presentation on mass spectrometry, we should cite the existence of spectrometers for which the method of sorting ions coming from the source is different from the magnetic sector. These are mainly quadripolar analyzers and, to a lesser degree, analyzers measuring the ion s time of flight.  [c.53]

Other techniques for predicting the cetane number rely on chemical analysis (Glavinceski et al., 1984) (Pande et al., 1990). Gas phase chromatography can be used, as can NMR or even mass spectrometry (refer to 3.2.1.l.b and  [c.220]

W. V. Ligon, Jr., Evaluating the Composition of Liquid Surfaces Using Mass Spectrometry, in Biological Mass Spectrometry, Elsevier, Amsterdam, 1990.  [c.325]

Benninghoven A, Rudenauer F G and Werner FI W 1987 Secondary ion Mass Spectrometry Basic Concepts, instrumentai Aspects, Appiications, and Trends (New York Wiley)  [c.319]

Castleman A W and Mark T D 1986 Cluster ions their formation, properties, and role in eluoidating the properties of matter in the oondensed state Gaseous Ion Chemistry and Mass Spectrometry ed J FI Futrell (New York Wiley)  [c.826]

Viggiano A A 1993 In-situ mass spectrometry and ion chemistry in the stratosphere and troposphere Mass Spectron. Rev. 12 115-37  [c.827]

Arnold F and Viggiano A A 1986 Review of rocket-borne ion mass spectrometry in the middle atmosphere Middie Atmosphere Program Handbook, Voi. 19 ed R A Goldberg (Urbana, IL SCOSTEP)  [c.828]

Schlager H and Arnold F 1985 Balloon-borne fragment ion mass spectrometry studies of stratospheric positive ions unambiguous detection of H (CH3CN), (H20)-clusters Pianet. Space Sc/. 33 1363-6  [c.828]

Mass spectrometry is one of the most versatile methods discussed in this encyclopedia. Ask a chemist involved in synthesis about mass spectrometry and they will answer that it is one of their most usefiil tools for identifying reaction products. An analytical chemist will indicate that mass spectrometry is one of the most sensitive detectors available for quantitative and qualitative analysis and is especially powerfiil when coupled to a separation technique such as gas clnomatography. A physicist may note that high resolution mass spectrometry has been responsible for the accurate detennination of the atomic masses listed in the periodic table. Biologists use mass spectrometry to identify high molecular weight protems and nucleic acids and even for sequencing peptides. Materials scientists use mass spectrometry for characterizing the composition and properties of polymers and metal surfaces.  [c.1328]

There are tliree basic light sources used in mass spectrometry the discharge lamp, the laser and the synclirotron light source. Since ionization of an organic molecule typically requires more than 9 or 10 eV, light sources for photoionization must generate photons m tlie vacuum-ultraviolet region of the electromagnetic spectrum. A connnon experimental difficulty with any of these methods is that there can be no optical windows or lenses, the light source being directly connected to the vacuum chamber holding the ion source and mass spectrometer. This produces a need for large capacity vacuum pumping to keep the mass spectrometer at operating pressures. Multiphoton ionization with laser light in the visible region of the spectrum overcomes this difficulty.  [c.1330]

One feature connnon to all of the above ionization methods is the need to themially volatilize liquid and solid samples into the ion source. This presents a problem for large and/or involatile samples which may decompose upon heating. Ionization teclmiques that have been developed to get around this problem include fast-atom bombardment (FAB) [3], matrix-assisted laser desorption ionization (MALDI) [4] and electrospray ionization (ES) [5] (figure B 1.7.2). FAB involves bombarding a sample that has been dissolved in a matrix such as glycerol with a high energy beam of atoms. Sample molecules that have been protonated by the glycerol matrix are sputtered off the probe tip, resulting in gas-phase ions. If high energy ions are used to desorb the sample, the teclmique is called SIMS (secondary ion mass spectrometry). MALDI mvolves ablating a sample with a laser. A matrix absorbs the laser light, resulting in a plume of ejected material, usually containing molecular ions or protonated molecules. In electrospray, ions are fomied in solution by adding protons or other ions to molecules. The solution is sprayed tln-ough a fine capillary held at a high potential relative to ground (several keV are common). The sprayed solution consists of tiny droplets that evaporate, leaving gas-phase adduct ions which are tiien introduced into a mass spectrometer for analysis.  [c.1331]

Fourier transfomr ion cyclotron resonance (FT-ICR) mass spectrometry is another in the class of trapping mass spectrometers and, as such is related to the quadnipole ion trap. The progenitor of FT-ICR, the ICR mass spectrometer, originated just after the Second World War when tire cyclotron accelerator was developed into a means for selectively detecting ions other than protons. At the heart of ICR is the presence of a magnetic field that confines ions into orbital trajectories about their flight axis. Early ICR experiments mainly took advantage of this trapping and were focnsed on ion-molecnle reactions. The addition of the tlnee-dimensional trapping cell by Mclver m 1970 [4T, 42] led to improved storage of ions. In 1974 Comisarow and Marshall introdnced the Former transfonn detection scheme that paved the way for FT-ICR [43, 44] which is now employed in virtually all areas in physical chemistry and chemical physics that rise mass spectrometry.  [c.1355]

See pages that mention the term Mass spectrometry : [c.11]    [c.34]    [c.49]    [c.81]    [c.695]    [c.814]    [c.1037]    [c.1328]    [c.1329]    [c.1353]    [c.1358]   
See chapters in:

Thiazole and its derivatives Ч.1  -> Mass spectrometry

Thiazole and its derivatives Ч.1  -> Mass spectrometry

Mass Spectrometry Basics  -> Mass spectrometry

Encyclopedia of chemical technology volume 15  -> Mass spectrometry

Comprehesive Heterocyclic Chemistry volume 4  -> Mass spectrometry

Comprehesive Heterocyclic Chemistry volume 5  -> Mass spectrometry

Comprehesive Heterocyclic Chemistry volume 6  -> Mass spectrometry

A guide to chalcogen-nitrogen chemistry  -> Mass spectrometry

The molecular modeling workbook for organic chemistry  -> Mass spectrometry

Advances in heterocyclic chemistry Vol.76  -> Mass spectrometry

Thiazole and its derivatives Ч.1 (1979) -- [ c.81 ]

Carey organic chemistry (0) -- [ c.567 , c.568 , c.569 , c.570 , c.571 , c.572 , c.577 ]

Mass Spectrometry Basics (2003) -- [ c.4 , c.71 , c.77 , c.245 ]

13 Chemistry in the Marine Environment (2000) -- [ c.46 ]

Chemistry of Organic Fluorine compounds II (1995) -- [ c.1031 , c.1032 ]

Organic chemistry (0) -- [ c.567 , c.568 , c.569 , c.570 , c.571 , c.572 , c.577 ]

A guide to chalcogen-nitrogen chemistry (1926) -- [ c.47 ]

Advances in heterocyclic chemistry Vol.80 (2001) -- [ c.0 ]

Advances in heterocyclic chemistry Vol.85 (2003) -- [ c.0 ]