Hydrocarbons detection

Fig. 14-5. Schematic diagram of hydrocarbon detection by gas chromatography. NMVOC, nonmethane volatile organic carbon.

The distribution of hydrocarbon products found with the Ir4(CO),2/ A1C13 system is unusual in that of the four hydrocarbons detected, i.e., methane, ethane, propane, and isobutane, ethane is the major product. At the initial stage of the reaction, the ethane-to-methane ratio is 10 1, decreasing to 2 1 after 0.5-3 days. The reason for this variation with reaction time is not clear, although it was felt unlikely that it resulted from ethane being cracked to methane during the course of the reaction (59). 

Trimmell, M. L., 1987, Installation of Hydrocarbon Detection Wells and Volumetric Calculations within a Confined Aquifer In Proceedings of the National Water Well Association of Ground Water Scientists and Engineers and the American Petroleum Institute Conference on Petroleum Hydrocarbons and Organic Chemicals in Ground Water Prevention, Detection and Restoration, November, pp. 255-269. 

The majority of the hydrocarbons detected by this geochemical technique have been proven to originate from bacteriological activity at depth. The heavier SGH compounds are robust and thus a wide variety of sample types may be used which is valuable in sampling in difficult Canadian environments. SGH is able to... 

Storm runoff from an industrial site in Rhode Island used by oil distributors, scrap metal dealers, and metal finishers contained a hydrocarbon product resembling fuel oil no. 2. This product comprised 4% of the total petroleum hydrocarbons detected in the ranoff, most of which were associated with crankcase oil (Latimer et al. 1990). Two freighters collided off the coast of South Africa in 1992 the freighter transporting 160 tons of marine fuel oil and 53 tons of gas oil sank (Molden 1992). 

Aromatic Hydrocarbons, Detection in Aqueous Solutions. Presence of small amts of aromatic hydrocarbons in water (1 to 500 ppm) may be detected by means of form aldehyde-sulfuric acid reagent as described by H.E.Morris et al, IEC, AnalEd 18, 294-5(1946)... 

Figure 3.17—Chromatogram of a mixture ofpolycyclic aromatic hydrocarbons. Detection by fluorescence (reproduced by permission of Chrompack).

Table 16.2 Polycyclic aromatic hydrocarbons detected in Ottawa drinking water...

All the binary Cu/ZnO catalysts were found highly selective toward methanol without DME, methane, or higher alcohols and hydrocarbons detected in the product by sensitive gas chromatographic methods (59). Several of the composites were also found to be very active when subjected to a standard test with synthesis gas C0/C02/H2 = 24/6/70 at gas hourly space velocity of 5000 hr- pressure 75 atm, and temperature 250°C. The activities, expressed as carbon conversions and yields, are summarized in Table VIII. The end members of the series, pure copper and pure zinc oxide, were inactive under these testing conditions, and maximum activity was obtained for the composition Cu/ZnO = 30/70. The yields per unit weight, per unit area of the catalyst or the individual components, turnover rates per site titratable by irreversible oxygen and by irreversible carbon monoxide, are graphically... 

Hints on the presence of silicone deposits are given by the adhesive strip test (lowering of the adhesion due to silicone) and the foam test (marked formation of foam when the textile sample is shaken with chlorinated hydrocarbons). Detection by means of IR spectroscopy is discussed in Section 8.4.4. 

CN). Colorimetric tubes are available which can detect halogenated hydrocarbons. Detection of agents with PIDs or FIDs may be possible. Detection and identification of agent vapors with FT-IR is possible provided that the appropriate reference spectra are available. Incendiary aerosols of Tear Agents may not be detectable by FT-IR because of detraction of the beam. 

Falate R, Kamikawachi RC, Muller M, Kalinowski HI, Fabris JL (2005) Fiber optic sensors for hydrocarbon detection. Sensors Actuators B Chem 105 430-436... 

Klemba F, Gusso Rosado R H, Kamikawachi RC, Muller M, Fabris JL (2006) Optical fiber sensors for petroleum hydrocarbon detection in pipelines. XXIX Encontro Nacional de Fisica da Materia Condensada, 2006, Sao Louren o-Brazil. Optics Technical Digest, ID 559... 

Conversion of benzene. In the above stated conditions benzene conversion varied from 0 to 10 % depending on the catalyst considered. The more dealuminated support HY45 gave no conversion at all. The only other hydrocarbon detected at the reactor exit was methane, resulting from the decomposition of DMDS. 

Kubelkova et al. carried out experiments on dealuminated zeolite Y, with a Si/Al molar ratio of 5.7, under 3 x 10 j0/h flow conditions and low-pressure (1 to 3 Pa) at 670 K. The main hydrocarbons detected were olefins and aromatics up to C. The... 

P. H. Emmett Johns Hopkins University)-. The adsorption measurements to which I referred in my paper included normal butane, normal heptane, and normal octane at a presssure of 4 mm. and at temperatures up to about 350°. In addition, measurements were made at 1 atm. pressure by a different technique on normal butane at temperatures as high as 531°. These measurements, therefore, extended into the region in which butane begins to crack quite readily. At no point was any appreciable chemisorption of any of these hydrocarbons detected, though a deposition of carbon caused a gradual weight increase in the catalyst when the latter was held at 530° in butane. 

The association reactions observed are strongly exothermic h So that the adducts can survive intact, the reaction heat must be dissipated by collisions or photon emission. Because association takes place at pressures <1x10" Torr, photon emission is the most likely means of stabilization h Further, the stability of the association products suggests that these species are covalently bound rather than loosely held ion-molecule complexes h The addition and condensation pathways occurring in the ICR cell could be the source of the large unsaturated hydrocarbons detected in flames and astrochemical environments. 

The limit of detection (LOD) for an acceptable GC-IR response for most compotmds is between about 1 and 20 ng (injected) per component, the actual value depending on the chemical nature of the analyte. The LOD is often defined with respect to the strongest band in the spectrum. Most bands in the infrared spectrum of nonpolar compounds are fairly weak and so these compounds tend to have the highest LODs, but even these compounds usually have at least one band in the spectrum with a high absorptivity. Examples include the C-H stretching bands of alkanes and the aromatic C-H out-of-plane deformation bands of polycyclic aromatic hydrocarbons. Detection limits also depend on the width of the GC peak the wider the peak, the more dilute the analyte and the higher the LOD. 

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