Carbon monoxide detection

Two tests were used for the detection of glycolic acid the chromatropic acid test and the method whereby the glycolic acid is treated with sulfuric acid and the resulting carbon monoxide detected by phosphomolybdic acid-palladium chloride reagent (10, 12). 

Caution. The synthesis uses carbon monoxide—a highly toxic, colorless, and odorless gas—therefore the preparation should be carried out in a well-ventilated room. Carbon monoxide detection systems are available from Devco. In the reaction benzene and Os(CO)s are formed, the benzene vapors are noxious and probably carcinogenic. The work-up should be performed in a well-ventilated hood. 

Sensors for carbon monoxide detection are well established, using Au/a-Fe2O3105 107 with gold particle sizes between 3.2 and 8.8 nm. Particles... 

Azad A-M, MhaisaUcar SG, Birkefeld LD, Akbar S A, Goto KS. Behavior of a new Zr02-M0O3 sensor for carbon monoxide detection. J Electrochem Soc 1992 139 2913-20. ICDD reference card 05-0408. 

Hinckley, C.C, et ah, Carbon monoxide detection of chemisorbed oxygen in coal and other carbonaceous materials. Fuel, 69(1), 103-109(1990). 

One of the indications and criteria of the complexity of a reaction mechanism is the generation of intermediates. Any species generated and consumed in the course of the reaction is referred to as intermediate. Note that the chemical nature of a species is an insufficient criterion as to whether the species is an intermediate or a reaction product. Depending on the reaction conditions, the same species can be either an intermediate or a reaction product. For example, hydrogen and carbon monoxide, detected in the products of slow hydrocarbon oxidation together with water and carbon dioxide, are reaction products. The same hydrogen and carbon monoxide detected in the inner cone of a Bunsen flame are virtually absent from the products of hydrocarbon combustion and must thus be considered as intermediates in this reaction. 

Carbon monoxide detection using a electrolyte and rare earths 241... 

A unique proposed applieation for an yttria-stabilized zirconia is in carbon monoxide detection. A platinum electrode is attached on both sides of a zirconia electrolyte. One side is covered with a platinum eatalyst on a porous alxunina substrate and the Pt electrode is not in direct contact with the sample gas. Platinum on the substrate acts as a catalyst for CO oxidation. A cross-sectional view of the CO sensor is shown in fig. 15 (Okamoto et al. 1980) (the operating temperature is around 300°C). When carbon monoxide exists in the atmosphere, most will be eatalytically oxidized by the oxygen in air during difiusion through the porous substance. Therefore, the gas that reaches the Pt electrode is not CO but a CO2-O2 mixture. On the other hand, on the surface of the platinum electrode without the catalyst, carbon monoxide is oxidized to CO2 and causes an anomalous EMF. This potential shows a one-to-one correspondence to the CO concentration. The typical performance of the CO sensor in air at 300°C is shown in fig. 16 (Okamoto et al. 1980). The EMF output increases with the CO content, but the slope of the curve decreases gradually. This sensor can operate at temperatures between 260 and 350 C and no speeial O2 reference gas is necessary. 

The material to be analyzed is pyrolyzed in an inert gas at 1100°C in the presence of carbon the carbon monoxide formed, if any, is either analyzed directly by chromatography or analyzed as carbon dioxide after oxidation by CuO. The CO2 is detected by infra-red spectrometry or by gas phase chromatography. 

Furfural is very thermally stable in the absence of oxygen. At temperatures as high as 230°C, exposure for many hours is required to produce detectable changes in the physical properties of furfural, with the exception of color (17). However, accelerating rate calorimetric data shows that a temperature above 250°C, in a closed system, furfural will spontaneously and exothermically decompose to furan and carbon monoxide with a substantial increase in pressure. The pressure may increase to 5000 psi or more, sufficient to shatter the container (18). 

Reference methods for criteria (19) and hazardous (20) poUutants estabHshed by the US EPA include sulfur dioxide [7446-09-5] by the West-Gaeke method carbon monoxide [630-08-0] by nondispersive infrared analysis ozone [10028-15-6] and nitrogen dioxide [10102-44-0] by chemiluminescence (qv) and hydrocarbons by gas chromatography coupled with flame-ionization detection. Gas chromatography coupled with a suitable detector can also be used to measure ambient concentrations of vinyl chloride monomer [75-01-4], halogenated hydrocarbons and aromatics, and polyacrylonitrile [25014-41-9] (21-22) (see Chromatography Trace and residue analysis). 

Nickel Carbonyl The extremely toxic gas nickel carbonyl can be detected at 0.01 ppb by measuring its chemiluminescent reaction with ozone in the presence of carbon monoxide. The reaction produces excited nickel(II) oxide by a chain process which generates many photons from each pollutant molecule to permit high sensitivity (315). 

The effect of accumulation in various systems depends greatly on the quantity of pollutants involved. Many pollutants can be detected at concentrations lower than those necessary to affect human health. For pollutants which are eliminated slowly, individuals can be monitored over long periods of time to detect trends in body burden the results of these analyses can then be related to total pollutant exposure. Following are two examples of air pollutants that contribute to the total body burden for lead and carbon monoxide. 

Thermal Conductivity Detector In the thermal conductivity detector (TCD), the temperature of a hot filament changes when the analyte dilutes the carrier gas. With a constant flow of helium carrier gas, the filament temperature will remain constant, but as compounds with different thermal conductivities elute, the different gas compositions cause heat to be conducted away from the filament at different rates, which in turn causes a change in the filament temperature and electrical resistance. The TCD is truly a universal detector and can detect water, air, hydrogen, carbon monoxide, nitrogen, sulfur dioxide, and many other compounds. For most organic molecules, the sensitivity of the TCD detector is low compared to that of the FID, but for the compounds for which the FID produces little or no signal, the TCD detector is a good alternative. 

No information was found on the transformation of diisopropyl methylphosphonate in the atmosphere. Based on the results of environmental fate studies of diisopropyl methylphosphonate in distilled water and natural water, photolysis (either direct or indirect) is not important in the transformation of diisopropyl methylphosphonate in aquatic systems (Spanggord et al. 1979). The ultraviolet and infrared laser-induced photodegradation of diisopropyl methylphosphonate in both the vapor or liquid phase has been demonstrated (Radziemski 1981). Light hydrocarbon gases were the principal decomposition products. Hydrogen, carbon monoxide (CO), carbon dioxide (C02), and water were also detected. 

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