Chemical analysis gases

Taird, C. K., in Instrumentation Reference Book (ed. Noltingk, B. E.), Chapter 5, Chemical analysis —gas analysis (Butterworths, London, 1988). 

Chemical Analysis. Gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) techniques were used to analyze 4-chlorophenol and its oxidation intermediates. For GC-MS analysis, the samples were acetylated in pyridine. The samples were first evaporated to dryness. Then 200 xL of pyridine and 200 (xL of acetic anhydride were added to the dry residue. The samples were heated at 65 °C for 2-3 h to ensure the complete acetylation reaction, and then gently evaporated to dryness in a nitrogen stream. Finally, the residue was redissolved in 0.1 mL of hexane for GC analysis. A GC (HP model 5890) equipped with mass selective detector (HP model 5971) and SPB-5 capillary column (Supelco Co., PA., 25- X 0.2-mm i.d. X 0.33-p.m film thickness) was used. To separate different intermediate products, various oven-temperature programs were performed. The GC-MS interface line was maintained at 300 °C. The mass-... 

These data were measured by chemical analysis, gas chromatography, beta-ray scintillation and gamma-ray spectrometry. The sodium impurity concentrations were also determined by the sodium temperature in the plugging indicator. As an example, the trend of oxygen and hydrogen in the primary sodium are shown in Fig. 11. 

Fuj] Chemical analysis, gas chromatography 1550°C, solubility and activity of Ca and 0 in CaO-Ca-0 alloy-molten Fe under variable calcium potential. 

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 3.2.2.2). 

Krypton clathrates have been prepared with hydroquinone and phenol. 85Kr has found recent application in chemical analysis. By imbedding the isotope in various solids, kryptonates are formed. The activity of these kryptonates is sensitive to chemical reactions at the surface. Estimates of the concentration of reactants are therefore made possible. Krypton is used in certain photographic flash lamps for high-speed photography. Uses thus far have been limited because of its high cost. Krypton gas presently costs about 30/1. 

Volatile impurities, eg, F2, HF, CIF, and CI2, in halogen fluoride compounds are most easily deterrnined by gas chromatography (109—111). The use of Ftoroplast adsorbents to determine certain volatile impurities to a detection limit of 0.01% has been described (112—114). Free halogen and haHde concentrations can be deterrnined by wet chemical analysis of hydrolyzed halogen fluoride compounds. 

Acetylene Derived from Hydrocarbons The analysis of purified hydrocarbon-derived acetylene is primarily concerned with the determination of other unsaturated hydrocarbons and iaert gases. Besides chemical analysis, physical analytical methods are employed such as gas chromatography, ir, uv, and mass spectroscopy. In iadustrial practice, gas chromatography is the most widely used tool for the analysis of acetylene. Satisfactory separation of acetylene from its impurities can be achieved usiag 50—80 mesh Porapak N programmed from 50—100°C at 4°C per minute. 

In plasma chromatography, molecular ions of the heavy organic material to be analy2ed are produced in an ionizer and pass by means of a shutter electrode into a drift region. The velocity of drift through an inert gas at approximately 101 kPa (1 atm) under the influence of an appHed electric field depends on the molecular weight of the sample. The various sonic species are separated and collected every few milliseconds on an electrode. The technique has been employed for studying upper atmosphere ion molecule reactions and for chemical analysis (100). 

Anions of another group were derivatized with formation of gaseous chemiluminescing species. Chemical reaction - gas extraction has been used with chemiluminescence detection in the stream of canier gas in on-line mode. Rate of a number of reactions has been studied as well as kinetic curves of extraction of gaseous products. Highly sensitive and rapid hybrid procedures have been developed for the determination of lO, BrO, CIO, CIO, NO,, N03, CrO, CIO, Br, T, S, 803 with detection limits at the level of pg/L, duration of analysis 3 min. 

Carbon monoxide is a colourless, odourless gas and - without chemical analysis - its presence is undetectable. It is produced by steam reforming or incomplete combustion of carbonaceous fuels typical carbon monoxide concentrations in common gases are given in Table 5.30. 

Gravimetric analysis The chemical analysis of materials by the separation of the constituents and their measurement by weight. This describes the gas mixture by giving the percentage by weight of each component gas. See also Volumetric analysis. 

Very little in the way of advances has occurred since 1971 in the applications of ultraviolet or infrared spectroscopy to the analysis of fluonnated organic compounds Therefore, only gas-liquid chromatography, liquid chromatography, mass spectrometry, and electron scattering for chemical analysis (ESCA) are discussed The application of nuclear magnetic resonance (NMR) spectroscopy to the analysis of fluonnated organic compounds is the subject of another section of this chapter... 

It was concluded [734] from visual inspection and chemical analysis of partially decomposed dolomite, that reaction was initiated at the outer surfaces of the crystallites and the interface established advanced thereafter into the bulk. The deceleratory a—time curves obeyed the contracting volume equation [eqn. (7), n = 3] and the values of E determined were between 206 and 232 kJ mole-1. These values of E were generally greater than those reported for other studies ( 190 kJ mole-1) which are in the range mentioned [121] for CaC03 dissociation and slightly larger than the enthalpy of that reaction. On exposure of the residue from vacuum decomposition of dolomite to C02, the gas uptake at 1070 K was... 

A. Mandelis, and C. Christofides, Solid State Gas Sensor Devices, in Chemical Analysis, John Wiley Sons, New York (1993). 

Charles s law The volume of a given sample of gas at constant pressure is directly proportional to its absolute temperature V T. chelate A complex containing at least one polydentate ligand that forms a ring of atoms including the central metal atom. Example [Co(en)3]3+. chemical analysis The determination of the chemical composition of a sample. See also qualitative, quantitative. 

The control of materials purity and of environmental conditions requires to implement physico-chemical analysis tools like ESC A, RBS, AUGER, SEM, XTM, SIMS or others. The principle of SIMS (Secondary Ion Mass Spectroscopy) is shown in Eig. 31 an ion gun projects common ions (like 0+, Ar+, Cs+, Ga+,. ..) onto the sample to analyze. In the same time a flood gun projects an electron beam on the sample to neutralize the clusters. The sample surface ejects electrons, which are detected with a scintillator, and secondary ions which are detected by mass spectrometry with a magnetic quadrupole. 

Concrete applications of micro reactors for chemical analysis, albeit so far not a core application, have been described [5]. Among other uses in chemical analysis, micro devices for gas chromatography, infrared spectroscopy, and photoacoustic detection are mentioned. 

Liquid feed was fed by hydrostatic means gas feed was accomplished from a reservoir with the aid of a syringe pump [7]. The gas pressure was held nearly constant by passing a gas stream into a non-absorbing liquid. Analysis was performed both by visual means using a microscope and camera and by chemical analysis of the liquid output solution (Figure 5.33). 

Ueiano GA and Geavatt CC (1977) The role of reference materials and reference methods in chemical analysis. CRC Crit Rev Anal Chem 6 361-411. 

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