Reaction spectrometry

Figure 2.6 Impact of coadsorbed oxygen and surface-alloyed Au on the decomposition of crotonaldehyde and propene over a Pd(l 1 1) model catalyst determined by temperature-programmed reaction spectrometry. (Adapted from Ref [87] by permission of the PCCP Owner Societies.)...

The thermal films and tribofilms produced on air-oxidized iron surfaces at 373 K in the presence of tributyl thiophosphate were studied by in situ attenuated total reflection (ATR/FT-IR) tribometry, XPS, and temperature programmed reaction spectrometry (TPRS) [14], Iron polyphosphate and sulfate were detected on the iron surface for both thermal films and tribofilms. After tribological tests, however, the amounts of sulfate and polyphosphate in the films were higher. The presence of sulfur in tributyl thiophosphate was found to favor the formation of long-chain iron polyphosphate and to lower the temperature of chemical and tribochemical reactions by around 50 K compared to the surface reaction of tributyl phosphate [7, 14], The reaction between TBT and iron was proposed to occur via an initial P=S bond scission to give tributyl phosphite. In accordance... 

Having demonstrated that odor of high intensity emanated from polyester fabrics and that this continued to emanate from polyester fabrics even after 28 days, McQueen sought to detect possible compounds in the headspace above the wool, cotton, and polyester fabrics using the instrumental technique of proton-transfer-reaction spectrometry (McQueen et al., 2008). Malodors continued to increase over 7 days with the polyester fabrics, but not with either the wool or the cotton fabrics, with the intensity of axillary odor seemingly inversely related to fiber hygroscopicity. 

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]. 

Freiser B S 1988 Fourier transform mass spectrometry Techniques for the Study of Ion-Molecule Reactions ed J M Farrar and W H Saunders (New York Wiley-Interscience)... 

The essentially non-destmetive nature of Rutherford backscattering spectrometry, combmed with the its ability to provide botli compositional and depth mfomiation, makes it an ideal analysis tool to study thm-film, solid-state reactions. In particular, the non-destmetive nature allows one to perfomi in situ RBS, thereby characterizing both the composition and thickness of fomied layers, without damaging the sample. Since only about two minutes of irradiation is needed to acquire a Rutherford backscattering spectmm, this may be done continuously to provide a real-time analysis of the reaction [6]. 

In contrast to IR and NMR spectroscopy, the principle of mass spectrometry (MS) is based on decomposition and reactions of organic molecules on theii way from the ion source to the detector. Consequently, structure-MS correlation is basically a matter of relating reactions to the signals in a mass spectrum. The chemical structure information contained in mass spectra is difficult to extract because of the complicated relationships between MS data and chemical structures. The aim of spectra evaluation can be either the identification of a compound or the interpretation of spectral data in order to elucidate the chemical structure [78-80],... 

Reaction mechanisms, infrared spectroscopy, and mass spectrometry ... 

Molecular ion (Section 13 22) In mass spectrometry the species formed by loss of an electron from a molecule Molecular orbital theory (Section 2 4) Theory of chemical bonding in which electrons are assumed to occupy orbitals in molecules much as they occupy orbitals in atoms The molecular orbitals are descnbed as combinations of the or bitals of all of the atoms that make up the molecule Molecularity (Section 4 8) The number of species that react to gether in the same elementary step of a reaction mechanism... 

This accurate measurement of the ratio of abundances of isotopes is used for geological dating, estimation of the ages of antiquities, testing athletes for the use of banned steroids, examining fine details of chemical reaction pathways, and so on. These uses are discussed in this book under various headings concerned with isotope ratio mass spectrometry (see Chapters 7, 14, 15, 16, 17, 47, and 48). 

SRM. selected reaction monitoring SSMS. spark source mass spectrometry... 

Knewstubb, P.F., Mass Spectrometry and Ion-Molecule Reactions, Cambridge University Press, London, 1969. Laeter, J.R. di. Applications of Inorganic Chemistry, Wiley, New York, 2001. 

Analytical methods iaclude thin-layer chromatography (69), gas chromatography (70), and specific methods for determining amine oxides ia detergeats (71) and foods (72). Nuclear magnetic resonance (73—75) and mass spectrometry (76) have also been used. A frequentiy used procedure for iadustrial amine oxides (77) iavolves titratioa with hydrochloric acid before and after conversion of the amine to the quaternary ammonium salt by reaction with methyl iodide. A simple, rapid quaHty control procedure has been developed for the deterrniaation of amine oxide and unreacted tertiary amine (78). 

Colorimetric and Fluorimetric Analysis. The functional groups of amino acids exhibit Htde absorption of uv light from 210 to 340 nm where uv absorption spectrometry is most conveniently conducted. Thus color or fluorescence formation reactions are employed for amino acid detection (128). 

Qualitative. The classic method for the quaUtative determination of silver ia solution is precipitation as silver chloride with dilute nitric acid and chloride ion. The silver chloride can be differentiated from lead or mercurous chlorides, which also may precipitate, by the fact that lead chloride is soluble ia hot water but not ia ammonium hydroxide, whereas mercurous chloride turns black ia ammonium hydroxide. Silver chloride dissolves ia ammonium hydroxide because of the formation of soluble silver—ammonia complexes. A number of selective spot tests (24) iaclude reactions with /)-dimethy1amino-henz1idenerhodanine, ceric ammonium nitrate, or bromopyrogaHol red [16574-43-9]. Silver is detected by x-ray fluorescence and arc-emission spectrometry. Two sensitive arc-emission lines for silver occur at 328.1 and 338.3 nm. 

Liquid Ghromatography/Mass Spectrometry. Increased use of Hquid chromatography/mass spectrometry (Ic/ms) for stmctural identification and trace analysis has become apparent. Thermospray Ic/ms has been used to identify by-products in phenyl isocyanate precolumn derivatization reactions (74). Five compounds resulting from the reaction of phenyUsocyanate and the reaction medium were identified two from a reaction between phenyl isocyanate and methanol, two from the reaction between phenyl isocyanate and water, and one from the polymerisation of phenyl isocyanate. There were also two reports of derivatisation to enhance either the response or stmctural information from thermospray Ic/ms for linoleic acid hpoxygenase metabohtes (75) and for cortisol (76). 

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