In Atmospheric Samples

For the determination of iodine-127 in the atmosphere, samples are generally collected on activated charcoal. The charcoal must have an extremely low Iodine content so that the activity of Irradiated blanks Is minimal. Two procedures for the chemical treatment of airborne samples collected on charcoal are described below. 

In one Instance (246), the sample on charcoal was transferred after Irradiation to a hot solution of sodium hydroxide, lodate carrier was added, and the radioiodine oxidized to lodate by means of hypochlorite. Following reduction of lodate to Iodide with bisulfite in acidic medium, an I -I i edox cycle was carried out In an acetate buffered solution (pH 4). Iodide was finally precipitated as the silver salt. Appropriate Iodide standards were prepared and analyzed. 

In the other case (238), I solution (for chemical yield determination) was added to the sample on charcoal prior to Irradiation. The irradiated sample was simply leached with concentrated aqueous aimionia and palladium(II) iodide was precipitated. The error In the procedure was estimated as 20%. Although it was demonstrated that the aqueous anmnla leached iodine present in the iodide, molecular iodine, and iodate forms, no attempt was made to convert the Iodine leached completely to Iodide. 

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The concentration of SO2 in atmospheric samples can be determined by bubbling a sample of air through a trap containing H2O2. Oxidation of SO2 by H2O2 results in the... 

The data in Table 31.1 represent the concentrations of the trace elements Na, Cl and Si (columns) in atmospheric samples that have been collected at the prevailing wind directions of 0, 90, 180 and 270 degrees (rows). 

Concentrations of trace elements in atmospheric samples at prevailing wind directions... 

The SVD of the table of concentrations of trace elements in atmospheric samples yields (in accordance with Section 17.6) ... 

Preprocessing is the operation which precedes the extraction of latent vectors from the data. It is an operation which is carried out on all the elements of an original data table X and which produces a transformed data table Z. We will discuss six common methods of preprocessing, including the trivial case in which the original data are left unchanged. The effects of each of these six types of preprocessing will be illustrated numerically by means of the small 4x3 data table from the study of trace elements in atmospheric samples which has been used in previous sections (Table 31.1). The various effects of the transformations can be observed from the two summary statistics (mean and norm). These statistics include the vector of column-means m and the vector of column-norms of the transformed data table Z ... 

Air samples collected in one acrylonitrile-fiber plant ranged from 3 to 20 mg/m3 (EPA 1980a). Mean 24-hour acrylonitrile concentrations in atmospheric samples collected within 5 km of 11 factories producing or using acrylonitrile ranged from less than 0.1 to 325 pg/m (Suta 1979). The occurrence of acrylonitrile was correlated to wind patterns the highest concentrations were downwind of and in close proximity to the plant. The median concentration of acrylonitrile for 43 measurements in "source-dominated areas" (i.e., near chemical plants) was 2.1 pg/m (Brodzinsky and Sing 1983). There were no data available on the concentration of acrylonitrile in air near chemical waste sites, but because acrylonitrile is easily volatilized, this is an exposure pathway of concern. 

Jiang FS, Lee SC, Bakhtiar SN, et al. 1986. Determination of thorium, uranium and plutonium isotopes in atmospheric samples. J Radioanal NucI chem 100 65-72. 

HPLC methods with fluorescence detection have also been developed for the determination of nitro-policyclic aromatic hydrocarbons (PAHs) (among which 9-nitroanthracene and 1-nitronaph-thalene) [238] in atmosphere. Samples have been collected in a standard high-volume sampler with a Teflon-coated glass fiber filter, and the Soxhlet extraction was performed with dichloromethane as the solvent. RP HPLC/UV techniques are used for the determination of aldehydes, ketones, and carbonylic compounds after derivatization with DNPH [239],... 

Brzezinska-Paudyn A, VanLoon JC, Balicki MR. 1986. Multielement analysis and mercury speciation in atmospheric samples from the Toronto area. Water Air Soil Pollut 27 45-56. 

Given the very small amounts of material found in atmospheric samples, improvements in the Ames assay... 

Lamb, J. D., Eatough, D. J., and Smith, R. G. (1993) Determination of Fluoride in Atmospheric Samples Using Macrocycle-based Ion Chromatography, Int. J. Ertvir. Analyt. Chem. 56, 317-325. 

Smith RM, O Keefe PW, Aldous KM, et al. 1990b. Chlorinated dibenzofurans and dioxins in atmospheric samples from cities in New York. Environ Sci Technol 24 1502-1506. 

Air pollutants, transport, 4 Air sampling—See Interstitial air sampling Aldehydes, determination in atmospheric samples, 299 Allegheny Mountain acid deposition and atmospheric chemistry, 28-36 deposition budgets for sulfate and nitrate, 33... 

A Technique for Measuring Photochemical Reactions in Atmospheric Samples, Environ. Sci. Technol. (1970) 4 (6), 503-506. 

In instrument neutron activation analysis (INAA) a small fraction of the stable atomic nuclei present in the sample are made radioactive by irradiation with neutrons or other particles. By measuring the resulting radioactivity, the original elements present can be determined. Reactor or thermal neutrons are usually used. The method does not work well for certain key elements of environmental interest including silicon, sulfur, and lead. Table 6.2 shows INAA detection limits for various elements and typical concentrations of these elemenis in urban air. In atmospheric samples, the fiiiiii of detectability for a particular clement depends on the quantities of the other elements in the filter matrix. The table is based on a total air sample of 17 actually used in the measurements. The tabulated results show that all elements listed could be detected in this air volume with the exception... 

In addition, the alkoxy radical C13C.CH20 produces highly reactive phosgene (COCl2) (Platz et al. 1995 Nelson et al. 1990) that has been identified in atmospheric samples and was attributed to the transformation of gem-dichloro aliphatic compounds (Grosjean 1991). 

PAHs are measured directly from emission sources or indirectly as deposition from the atmosphere. Because of the comphcated nature of particulate and aerosol analysis, and the sheer number of PAH, OP AH, and NPAH compounds present in atmospheric samples, sample analysis is commonly... 

A summary of the retention indices of more than 80 alkyl nitrates has been reported. In general, the separation of the alkyl nitrates follows the order of boiling points in Table 19.8. The 1-n-alkyl nitrate is always the last member of each group to elute. Thus, it can be used as a window marker or retention index marker compound. The most abundant alkyl nitrates found in atmospheric samples are typically the secondary nitrates. For this reason, the 2-Cs and 2-Cio alkyl nitrates have also been suggested as marker compounds. ... 

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