Ozone, detector

Ozone decay was measured in an office, a home, and several metal test facilities. Measurements were carried out with a Mast ozone meter and an MEC chemiluminescence ozone detector. The latter was calibrated with a stable ozone source and the epa neutral buffered potasaum iodide procedure. (It was noted over a wide range of concentrations that the mec meter measurements were consistently higher than those of the Mast meter by a factor of 1.3. That this is essentially identical with the findings of the DeMore committee is interesting.) Ozone generated by a positive corona ionizer was introduced into the test facilities. Ozone decay in a metal-walled room was found to be first-order, with the rate constant... 

Carbon Monoxide. It was found that 20 p.p.m. of carbon monoxide do not interfere with the operation or sensitivity of the analyzer. This result is surprising, because the catalyst used in this study (Hopcalite) is also used to detect carbon monoxide in a device manufactured by the Mine Safety Appliances Co. However, the catalyst must be carefully dried prior to use in order to decompose any carbon monoxide present. The inertness of the ozone detector to carbon monoxide in these experiments may be attributed to the poisoning of the catalyst by the water vapor normally present in the atmosphere. 

Oxygen Detectors Ozone Detectors Oxygen handling devices Oxygen fired incinerators Ozone generators... 

Bender M., Fortunato E., Nunes R, Eerreira L, Marques A., Martins R., Katsarakis N., Cimalla V., and Kiriakidis G., Highly sensitive ZnO ozone detectors at room temperature, Jpn. J. Appl. Phys., 42, L435-L437, 2003. 

D OZONE DETECTOR R = REFERENCE SIDE S > SAMPLE SIDE RV ROTARY VALVE CSTR = STIRRED TANK REACTOR S = SAMPLE POINT... 

FIGURE 1 Set-up of ozone detector for identification of separated by liquid chromatography chemical compounds. 1 - eluent access la - entry for pouring out the elate as thin film on 2 - solid glass stick 3 - outer glass jacket 4 - vessel for eluent accumulation 4a - hydraulic detente 5 - tap for pouring out the eluate 6 - ozone inlet 7 - ozone outlet. 

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). 

Because process mixtures are complex, specialized detectors may substitute for separation efficiency. One specialized detector is the array amperometric detector, which allows selective detection of electrochemically active compounds.23 Electrochemical array detectors are discussed in greater detail in Chapter 5. Many pharmaceutical compounds are chiral, so a detector capable of determining optical purity would be extremely useful in monitoring synthetic reactions. A double-beam circular dichroism detector using a laser as the source was used for the selective detection of chiral cobalt compounds.24 The double-beam, single-source construction reduces the limitations of flicker noise. Chemiluminescence of an ozonized mixture was used as the principle for a sulfur-selective detector used to analyze pesticides, proteins, and blood thiols from rat plasma.25 Chemiluminescence using bis (2,4, 6-trichlorophenyl) oxalate was used for the selective detection of catalytically reduced nitrated polycyclic aromatic hydrocarbons from diesel exhaust.26... 

Ryerson, T. B., Dunham, A. J., Barkley, R. M., and Sievers, R. E., Sulfur-selective detector for liquid chromatography based on sulfur monoxide-ozone chemiluminescence, Anal. Chem., 66, 2841, 1994. 

SCD Sulfur chemiluminescence detector (flame and flameless) Ozone-induced CL... 

Ozonolysis. Ozonolysis of the methylhexadiene polymer was conducted (21)at room temperature on a solution of 1,03 g. polymer in 20 ml. tetrahydrofuran with the aid of the Wellsbach ozonizer. The end point for the ozonolysis was observed after about 15 min. by the reaction of excess ozone with starch-iodide solution. Triphenylphosphine was added to the reaction mixture and allowed to react at room temperature for 60 hr. The resulting product was analyzed by GLC (Hewlett Packard 5750, Porapak Q 10 ft. x 1/8 in. column at 110°C, helium pressure 60 psi, thermal conductivity detector at 190°C, injector 200°c). 

J.S. Beckman and K.A. Congert, Direct measurement of dilute nitric oxide in solution with an ozone chemiluminescent detector. Methods 7, 35-38 (1995). 

The chemiluminescent reaction of SO with ozone is the basis of the sulfur chemiluminescence detector (SCD) [23] discussed later in this chapter,... 

As the reaction temperature is increased, chemiluminescence is observed in the reactions of ozone with aromatic hydrocarbons and even alkanes. Variation of temperature has been used to control the selectivity in a gas chromatography (GC) detector [35], At room temperature, only olefins are detected at a temperature of 150°C, aromatic compounds begin to exhibit a chemiluminescent response and at 250°C alkanes respond, giving the detector a nearly universal response similar to a flame ionization detector (FID). The mechanisms of these reactions are complex and unknown. However, it seems likely that oxygen atoms produced in the thermal decomposition of ozone may play a significant role, as may surface reactions with 03 and O atoms. 

Isoprene, the most abundant hydrocarbon emitted to the atmosphere by plants, can also be measured using ozone chemiluminescence. As discussed above, al-kenes react with ozone to produce formaldehyde in its A2 electronic state, in addition to several other chemiluminescent products. In a fast isoprene detector manufactured by Hills Scientific (Boulder, CO), the chemiluminescence is detected using a blue-sensitive PMT to maximize the sensitivity for isoprene detec-... 

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