Mist chambers

Stratton WJ, Lindberg SE, Perry C J. 2001. Atmospheric mercury speciation critical evaluation of a mist chamber method for measuring reactive gaseous mercury. Environ Sci Technol 35 170-177. 

Filters, Denuders, Transition Flow Reactors, Mist Chambers, and Scrubbers... 

Scrubbers. Mist chamber scrubbers have also been used for HN03. The airstream passes through a Teflon filter to remove particles and then encounters a mist of water that scrubs the HN03 out of the air. The nitrate concentration is measured in the aqueous scrubbing solution using ion chromatography (Talbot et al., 1990). 

Other approaches to collection of the carbonyl compounds include the use of impingers containing the DNPH in a solvent such as acetonitrile (e.g., Grosjean and Fung, 1982 Lipari and Swarin, 1982), scrubbers (e.g., Dasgupta et al., 1988, 1990 Lee and Zhou, 1993), mist chambers (e.g., Cofer and Edahl, 1986 Munger et al., 1995 Khare et al., 1997), and condensation collectors (Dawson and Farmer, 1988). 

Several techniques were used to detect reactive chlorine in the MBL. Keene et al. (1993) developed a tandem mist chamber to sample chlorine gases in the MBL. In the inlet both coarse and fine aerosol particles are removed. In the first (acidic mist chamber) the gases HCl, NOCl, CINO2, and CINO3 (=HC1 ) are sampled (HCl goes into solution at a pH greater than 1), whereas in the second (alkaline chamber) CI2 and HOCl (=Cf) are sampled. 

Stratton W. J. and Lindberg S. E. (1995) Use of a refluxing mist chamber for measurement of gas-phase mercury(ll) species in the atmosphere. Water Air Soil Pollut. 80, 1269-1278. 

Mist chambers function in a manner very similar to that of bubblers. In the mist chamber, a fine mist of water or other chemical is generated. The air sample is drawn into the mist chamber and the analyte is scavenged by the mist droplets. 

In these chambers it is not clear to what extent particles are scavenged. If particles are not to be sampled, then particle filters may be placed before the mist chamber. This, however, may result in the volatilization of particle-associated organics, as described previously. If water is used as the scavenging mist, the analytical method must be able to accommodate water. 

Improvements have been made recently for the preconcentration of gaseous methylmercury in air by preconcentration in mist chambers and subsequent determination by aqueous-phase ethylation, precollection on carbotrap columns, separation by GC, and detection by cold vapor atomic fluorescence spectrometry (CV-AFS). In order to understand the behavior and fate of mercury compounds in the atmosphere and their role in environmental mercury cycling, there is an urgent need for further development of analytical methods to afford identification of mercury species in the atmosphere by compound-specific analytical methods (as opposed to operationally defined protocols). 

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