Nitrates atmospheric sampling

Determination of several atmospheric oxidant species is critical to understanding gaseous and aqueous processes leading to acidic deposition. Hydrogen peroxide has a high Henry s Law solubility and must be measured in gaseous and aqueous atmospheric samples to better understand wet deposition processes. In contrast, measurements of ozone and peroxyacyl nitrates (PANs) (and probably alkyl hydroperoxides and peracids) usually need to be made only in the gas phase due to their low aqueous solubility (14). 

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... 

Alexander et al. (2002a,b,c) have measured the and 5 0 of both sulfate and nitrate from samples at Greenland ice core site A (70° 45 N, 35° 51.5, elevation 3,145 m). These samples were particularly interesting because, temporally, they surround the Industrial Revolution. The years spanned by these measurements are from around 1692 to 1976. The details of ice decontamination and chemistry are presented in Alexander et al. (2002a,b,c). These measurements have distinctly shown that biomass-buming events prior to the Industrial Revolution altered the atmospheric oxidative mechanisms in the northern hemisphere. This work is signrhcant in that (i) it further demonstrates how 5 0 measurements of... 

A series of hydroxy-, nitrooxy-, and dinitrooxyalkanes that are produced by reactions between alkenes and hydroxy and nitrate radicals were synthesized to develop procedures both for their collection from atmospheric samples and to facilitate their identification and analysis (Muthuramu et al. 1993). 

Spicer, C. W. and Schumacher, P. M., 1977 Interferences in sampling atmospheric particulate nitrate. Atmospheric Environment IL 873-876. 

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. ... 

Carbon Dioxide Adsorption on Dried Polymer. Other unexpected interactions of these hydrolytic polymers have been noted previously during the measurement of infrared spectra of dried Pu(IV) polymers (like those used for diffraction studies). Vibrational bands first attributed to nitrate ion were observed in samples exposed to room air however, these bands were not present in samples prepared under nitrogen atmospheres (see Fig. 4) (6). Chemical analyses established enough carbon in the exposed samples to confirm the assignment of the extraneous bands to the carbonate functional group... 

A different picture was obtained in the case of the reference Pt—BaAy-A Oj (1/20/100 w/w) sample (Figure 6.12). In the case of the TPD experiment performed after NO, adsorption at 350°C, the decomposition of stored NO, species was observed only above 350°C. Evolution of NO and 02 was observed in this case, along with minor quantities of N02 [25,28,33,35], Complete desorption of NO, was attained already slightly below 600°C. As in the case of the binary Ba/y-Al203 sample, the data hence indicate that nitrates formed upon N0/02 adsorption at 350°C followed by He purge at the same temperature, did not appreciably decompose below the adsorption temperature during the TPD run under inert atmosphere. 

Sometimes substances to be determined in gaseous samples are adsorbed on solid adsorbents and then transferred to solution. Thus nitrogen oxides present in the atmosphere are chemisorbed on lead dioxide heated to a temperature of 190 °C. The lead nitrate formed is extracted into hot water and the NO3 anion is then determined [29]. 

Hisham, M. W. M., and D. Grosjean, Sampling of Atmospheric Nitrogen Dioxide Using Triethanolamine Interference from Per-oxyacetyl Nitrate, Atmos. Environ., 24, 2523-2525 (1990). 

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