Analysis of aerosols

Zinsmeister, A. R. and Redman, T. C. (1980). A time series analysis of aerosol composition measurements, Atmos. Environ. 14,201-215. 

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. 

Schulten. H.-R., and U. Schurath. Analysis of aerosols from the ozonolysis of... 

A considerable effort has gone into the application of statistical techniques to the analysis of aerosol data for the extraction of source contributions. The use of novel statistical methods has been stimulated by uncertainties in the data collected in field measurements and in source characterization in some cases not all of the sources are known. 

Zinmeister, A.R. and Redman. T.C. (198Q). "A Time Series Analysis of Aerosol Composition Measurements," Atmospheric Environment, 14, 201. 

Schulten, H.-R., and U. Schurath, Analysis of Aerosols from the Ozonolysis of 1-Butene by High-Resolution Field Desorption Mass Spectrometry, . /. Phys. Chem., 79, 51-57 (1975). 

Carson, P. G K. R. Neubauer, M. V. Johnston, and A. S. Wexler, On-Line Chemical Analysis of Aerosols by Rapid Single-Particle Mass Spectrometry, J. Aerosol Sci., 26, 535-545 (1995). 

Faude, F., and J. Goschnick, XPS, SIMS, and SNMS Applied to a Combined Analysis of Aerosol Particles from a Region of Considerable Air Pollution in the Upper Rhine Valley, Fresenius J. Anal. Chem., 358, 67-72 (1997). 

Fung, K. H., and I. N. Tang, Analysis of Aerosol Particles by Resonance Raman Scattering Technique, Appl. Spectrosc., 46, 159-162 (1992a). 

Yang, M., P. T. A. Reilly, K. B. Boraas, W. B. Whitten, and J. M. Ramsey, Real-Time Chemical Analysis of Aerosol Particles Using an Ion Trap Mass Spectrometer, Rapid Commun. Mass Spectrom., 10, 347-351 (1996). 

Durkee, P. A., F. Pfeil, E. Frost, and R. Shema, Global Analysis of Aerosol Particle Characteristics, Atmos. Environ., 25A, 2457-2471 (1991). 

The argument can be made that some lack of precision and accuracy is only to be expected, given the formidable difficulties in accurate collection and compositional analysis of aerosols by size. Thus, while efforts are being... 

Optical Methods. Optical methods, based on the scattering of light by dispersed droplets, provide a relatively simple and rapid measure of particle size. However, optical techniques give data concerning the average drop size or the predominant size only, and size-distribution data cannot be obtained. Optical methods are more suited to the size analysis of aerosols and extremely fine mists than to the analysis of typical fuel sprays. 

One of the most successful applications of PIXE has been in the analysis of air pollution particulate matter. Atmospheric particulate matter is typically collected by impaction on a filter paper, which provides an ideal thin sample for PIXE analysis. Another aspect of PIXE that is very important for the analysis of aerosol samples is the ability to analyze a large number of samples in a short time. PIXE analyses typically take less than a minute, and the entire irradiation, counting, sample changing, and analysis procedure can be automated. 

Dhand, R., Malik, S. K., Balakrishnan, M., Verma, S. R. High speed photographic analysis of aerosols produced by metered dose inhalers. J Pharm Pharmacol 40 429-430 (1988). 

A schematic representation of the EGA apparatus used in our analysis of aerosol particles is shown in Figure 1. The sample, collected on a prefired quartz filter, is placed in the quartz combustion tube so that its surface is perpendicular to the tube axis. The tube is supplied with purified oxygen, with excess oxygen excaping through an axial opening at the end of the tube. 

Analysis of aerosol samples obtained at several locations in Western Europe has shown that about 60% of the content of organic carbon in tropospheric aerosol is the share of water-soluble organic compounds. According to observational data, at a rural location in Austria, mono- and dicarboxylic acids constitute about 11 % (with respect to the total content of organic carbon in cloud water). While insoluble organic compounds hamper the assimilation of water by aerosol, soluble organic matter, as a rule, favors water assimilation. 

Yu, C.P., Diu, C.K. Soong, T.T. (1981) Statistical analysis of aerosol deposition in the nose and mouth. American Industrial Hygiene Association Journal, 42,726-33. 

TABLE XXI. Comparison of results of three different analysts applying the ruggedized method to the analysis of aerosol generated filters. All data are expressed as yg/m % Std. Dev. 

A number of studies have speculated on diazotroph response to mineral dust Fe fertilization in the Atlantic (Mahaffey et al, 2003), and Pacific Oceans (Johnson et al, 2003). Circumstantial evidence for dust stimulation of marine diazotrophic biomass has recently been reported. A 1999 Saharan dust event coincided with increases in dissolved Fe concentrations on the west Florida shelf and a 100-fold increase in Trichodesmium biomass. N2 fixation rates were not measured, but DON concentrations doubled, presumably due to exudation by N2 fixers (Lenes et al, 2001). A recent Saharan dust addition experiment to surface water samples collected along a west African cruise transect (35°W-17°W), found a minimal increase in CO2 fixation and a large stimulation in N2 fixation, suggesting that diazotrophs were co-limited by both P and Fe (Mills et al, 2004). Note however, analysis of aerosol dust shows that while providing Fe, it also supplies P and combined N (Baker et al, 2003 Mills et al, 2004 Ridame and Guieu, 2002). 

Noble C. A. and Prather K. A. (2000) Real-time single particle mass spectrometry a historical review of a quarter century of the chemical analysis of aerosols. Mass. Spectrom. Rev. 19, 248-274. 

Colbeck, I. Eractal analysis of aerosol particles. Anal. Proc. 1995, 32, 383-386. 

Hotham, G.A. Particle size analysis of aerosols in medicine. In Respiratory Aerosols Gale, A.E., Ed. Gordon Harris St. Agnes, South Australia, 1981 47-71. 

Goetz, A. Application of the molecular filter membrane to the analysis of aerosols. Am. J. Publ. Health. 1953, 43, 150-159. 

Broekaert J. A. C., Wopenka B. and Puxbaum H. (1982) Inductively coupled plasma optical emission spectrometry for the analysis of aerosol samples collected by cascade impactors, Anal Chem 54 2174-2179. 

Mitchell JP, Nagel MW, Wiersema KJ, et al. Aerodynamic particle size analysis of aerosols from pressurized metered-dose inhalers comparison of Andersen 8-stage cascade impactor, next generation pharmaceutical impactor, and model 3321 aerodynamic particle sizer aerosol spectrometer. AAPS PharmSciTech 2003 4 E54. 

In addition, the cumulative size distribution obtained for pure micron-ized and supercritically produced powders, combined with computation of the aerodynamic diameter according to Eqs. (2) and (3), shows that FPF of supercritically produced particles is about 50%, twice as much as FPF for micronized powder and close to the dispersion efficiency found with lactose (76). The correct values for the total emitted dose of drug particles also were confirmed. In all cases, the state of dispersion for the different formulations was correctly predicted and the results obtained showed good agreement with the cascade impactor measurements made on the same samples. Therefore laser diffraction has distinct advantages over impactor techniques with respect to the speed and reproducibility of measurements and can be used as a complementary method for analysis of aerosol behaviour of different formulations. 

There are few methods suitable for on-line chemical analysis of aerosol particles. Raman spectroscopy offers the possibility of identifying the chemical species in aerosol particles because the spectrum is specific to the molecular. structure of the material, especially to the vibrational and rotational modes of the molecules. Raman spectra have been obtained for individual micron-sized particles placed on surfaces, levitated optically or by an eiectrodynamic balance, or by monodisperse aerosols suspended in a flowing gas. A few measurements have also been made for chemically mixed and poly disperse aerosols. The Raman spectrum of a spherical particle differs from that of the bulk material because of morphology-dependent resonances that re.su It when the Raman scattered photons undergo Mie scattering in the particle. Methods have been developed for calculating the modified spectra (McNulty el al., 1980). 

Gas-phase molecules in the atmosphere can be converted to the aero.sol phase by homogeneous (gas phase) or heterogeneous aerojtol phase) reactions. Both mechanisms may be operative over different particle size ranges. Information on the dominant growth mechanisms can be inferred by an analysis of aerosol dynamics in power plant plumes (McMurry et al., 1981 Wilson and McMurry. 1981). When homogeneous gas-phase reactions are controlling, there are two possible pathways for the reaction products to enter the size distribution function ... 

The quantitative analysis of aerosol extinction spectra is based on the Lambert Beer equation (1). The measured optical depth at a specific wavenumber Vj may be expressed as... 

The FTIR spectra showed that the aerosols formed contained hydrates, polymeric forms, acetals and hemiacetals. Several peaks in these spectra closely corresponded to peaks in FTIR spectra of aerosols collected in the Smoky Mountains (Jang et al. 2002). Czoschke et al. (2003) concluded, that in their experiments, isoprene had been oxidised to aldehydes by ozone in the gas phase, and the aldehydes had been converted to the observed products in heterogeneous, acid-catalysed reactions. However, the presented analysis of aerosol yields was very approximate, and did not exclude the possibility of heterogeneous reactions of isoprene in the discussed experiments. All the differences in reactors and techniques given, in the experiments by Limbeck et al. (2003) ozone reacted with isoprene in the gas phase, but decreased the amount of polymers formed. 

Filtration is used to collect all particles and is the most commonly used method when collection is done periodically (for example, over hours or days). Analysis of aerosols collected on filters requires rinsing or other methods to remove the particles from the filter. Although filtration can be very effective in collecting particles, the collected particles are not suitable for all types of analysis. For example, vegetative cells often dry out on filters, so viable organisms cannot be cultured from the filter. In addition, it takes time and different reagents... 

Wexler, A. S., and Seinfeld, J. H. (1992) Analysis of aerosol ammonium nitrate Departures from equilibrium during SCAQS, Atmos. Environ. 26A, 579-591. 

An excellent review on the use of INAA in the analysis of aerosols can be found in (Allan and Sansoni, 1985, 1990). Over 25 elements are easily and reliably determined in different aerosol filters. The use of epithermal and thermal irradiations increases the analytical parameters of the analysis for some of the elements (Allan et al., 1984, 1985). Forty-one elements have been successfully determined in combustion effluents from power plants (James and Acevedo, 1993). 

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