Chemiluminescence method atmosphere

McKee, H. C., R. E. Childers, and V. B. Parr. Cdlabroative Study of Reference Method for Measurement of Photochemical Oxidants in the Atmosphere (Ozone-Ethylene Chemiluminescent Method) EPA 650/4-75-016. San Antonio, Texas Southwest Research Institute, 1975. 49 pp. 

In the polluted atmosphere, the ultra-violet optical absorption technique (UV-photometer) does not always provides quality ozone data. A possible influence of various interferences on the measuring procedure can be responsible for this. The chemiluminescence method of O3 detection is considerably fi eer from interferences. ... 

Joseph, D. W., and C. W. Spicer (1978). Chemiluminescence method for atmospheric monitoring of nitric acid and nitrogen oxides. Anal. Chem. 50, 1400-1403. 

Chemiluminescence methods for determining components of gases originated with the need for highly sensitive methods for determining atmospheric pollutants such as o/.one, oxides of nitrogen, and sulfur compounds. One of the most widely used of these methods is for the determination of nitrogen monoxide with the reactions... 

The chemiluminescence method is accepted as the most reliable and precise method currently available for the analysis of oxides of nitrogen. The basis of the method is the reaction between atmospheric NO and O3 (generated within the instrument). This reaction generates light (chemiluminescence), which is detected by a photomultiplier and converted to a concentration by calibration of the instrument with standard gas mixtures. To determine the NO2 content of the air, NO2 must be converted by thermal decomposition to NO and the instrument then measures NO. NO2 is then determined by difference between the NO and NO channels. 

Another important chemiluminescence method is used for monitoring atmospheric ozone. In this instance, the determination is based on the luminescence produced when the analyte reacts with the dye Rho-damine B adsorbed on an activated silica gel surface. This procedure is sensitive to less than 1 ppb ozone. The response is linear up to 400 ppb ozone. Ozone can also be determined in the gas phase based on the chemiluminescence produced when the analyte reacts with ethylene. Both reagents are reported to be specific for ozone. 

Still another important gas-phase chemiluminescence method is used for the determination of atmospheric sulfur compounds such as hydrogen sulfide, sulfur dioxide, and mercaptans. Here, the sample is combusted in a hydrogen flame to give a sulfur dimer, which then decomposes with the emission of light. For example, with sulfur dioxide the reactions are... 

This analysis techniqne is illnstrative of chemiluminescence analysis in general. Chemiluminescence is an inherently desirable technique for the analysis of atmospheric pollutants because it avoids wet chemistry, is basically simple, and lends itself well to continuous monitoring and instrumental methods. Another chemiluminescence method, which is employed for the analysis of ozone, is described Section 18.20.5. 

For reaction (5.18) it has been shown from a crossed molecular beam experiment that the main process is CH2OH + H, and the process of CH3O + H is not important (Lin et al. 1998). Also for the physical deactivation pathway (5.20), Wine and Ravishankara (1982) and Takahashi et al. (1996) reported that the ratio is less than a few%, while the recent high precision experiment of Vranckx et al. (2008b) by using the chemiluminescence method showed that it is 0.2 0.3 % and that it is negligible as an atmospheric reaction. 

The principal method used for measuring NO2 is also based on chemiluminescence (Fig. 14-3) (5). NO2 concentrations are determined indirectly from the difference between the NO and NO (NO -I- NO2) concentrations in the atmosphere. These concentrations are determined by measuring the tight emitted from the chemiluminescent reaction of NO with 03 (similar to the reaction of O3 with ethylene noted for the measurement of O3), except that O3 is supplied at a high constant concentration, and the light output is proportional to the concentration of NO present in the ambient air stream. 

The chemical characterization of aerosol particles currently is of great interest in the field of atmospheric chemistry. A major goal is the development of a method for continuous elemental analysis of aerosols, especially for the elements C, N, and S. Chemiluminescence reactions described in this chapter have adequate sensitivity and selectivity for such analyses. In fact, considering that a 1- j.m-diameter particle has a mass of =0.5-1.0 pg, online analysis of single aerosol particles should be achievable, especially for larger particles. 

The technol( for the routine measurement of the nitrogen oxides (nitrogen dioxide and nitric oxide) is fairly well advanced. The epa is on the verge of officially proposing that chemiluminescence produced by the reaction of nitric oxide with ozone be the reference method for nitrogen dioxide.This method is even more suitable for nitric oxide. Because no national air quality standard has been promulgated for nitric oxide, no reference method will be specified. However, its measurement in the atmosphere is crucial for establishing the relation of its emission to the formation of atmospheric ozone and other photochemical oxidants. 

An informal intercomparison study of N02 measurements was carried out in a remote atmosphere at Izana, Tenerife (Zenker et al., 1998). Three techniques were used TDLS, photolysis with a chemiluminescence detector, and matrix isolation-ESR. Agreement between the three methods was good, with plots of data from one technique against the others having slopes within experimental error of unity. For example, TDLS and the photolysis technique plotted against the matrix isolation measurements had slopes of 0.90 + 0.47 and 1.04 + 0.34, respectively, over a range of NOz concentrations from 100 to 600 ppt. 

The formation and fate of peroxyacyl nitrates, RC(0)00N02, were discussed in Chapter 6.1. These compounds are almost universally measured using gas chromatography with electron capture detection (GC-ECD), although a luminol chemiluminescence detector has also been used in which PAN is thermally decomposed to N02 at the end of the column and the N02 measured (Burkhardt et al., 1988 Blanchard et al., 1990 Gaffney et al., 1998). In polluted atmospheres where the concentrations are higher, FTIR has also been used (Table 11.2). For a summary of methods, see reviews by Gaffney et al. (1989) and Kleindienst (1994). 

Maeda, Y., and N. Takenaka, Chemiluminescence Determination of Trace Amounts of Ammonia and Halogen Species in the Environment, in Optical Methods in Atmospheric Chemistry, SPIE, Vol. 1715, pp. 185-193, Bellingham, WA, 1992. 

Since chemiluminescence is a very sensitive method of studying oxidative degradation, it has been used to measure the effect of stress on oxidation of polymers, i.e. stress-induced chemiluminescence (SCL). SCL is by definition a type of triboluminescence, and it is likely that SCL and other forms of tri-boluminescence can occur at the same time. SCL is, however, the only type of tribo-induced luminescence that is oxygen dependent and can therefore be sorted out by measurements in inert and oxidative atmospheres. 

In the process of developing PRMs, it is necessary to study and establish measurement methods which are used to analyzed the purity of raw gases and verify the stability of the gas mixture kept in the cylinder. Up to now, NRCCRM has been equipped with several series of analytical techniques including atmospheric pressure ionization mass spectrometer, gas chromatograph, infra-red spectrophotometer with long-path gas cell, chemiluminescent, non-dispersive infra-red, minor 02 and H20 analyzer and so on. 

The reactor tube was brought to the required temperature under an atmosphere of argon. A mixture of nitric oxide and carbon monoxide or hydrogen, diluted by argon was then introduced into the reacting part of the quartz tube. The gaseous reaction products were intermittently withdrawn from the reactor and analyzed by a chemiluminescent NOx analyzer and a gaschromatograph. Ammonia was measured by detector tube method. The scope of the experiment is shown in Table II. 

The thermally degraded PECT samples (free additive and with stabilizers Irganox 3114 and Alkanox 28) were analyzed by chemiluminescence under nitrogen atmosphere, at 150°C. Under this condition, only one emission was observed as it was described for UV degraded samples. In general, a correlation can be established between the chemiluminescence intensity and the hydroperoxide content determined by the iodometric method at different aging times, in agreement with the results obtained by other authors [36]. 

Another method for the detection of the PANs involves thermal decomposition to NO2 and direct measurement with an NO chemiluminescence monitor. This instrument relies on the reaction of NO with O3 to produce excited NO2. The NO2 emission is a broadband chemiluminescence starting at about 600 run and peaking at A = 1.27 /rm (1270 nm). A red-sensitive photomultiplier is required to monitor the emission. To monitor NO2, the sample is first passed over a hot catalyst which converts the NO2 to NO. A number of atmospheric nitrates, including HNO3 and the PANs, are also decomposed by the hot catalyst to NO. The main drawback of this method for PAN detection is its sensitivity, which is limited to 1 to 2 ppbv because of the lack of sensitivity of commercial phototubes at the emission wavelength. This method is useful for calibration of other detectors with high purity standards under controlled laboratory conditions. 

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