Fine particle fraction

K, Ca, Ti, Fe and Sr. The second factor has high values for bromine and lead. This factor can be identified as motor vehicle exhaust. It does not have a large loading for mass. It would be expected that most of the motor vehicle mass would be found in the fine particle fraction. 

As lead in automotive emissions has been found largely in the fine particle fraction (22, 23), it is reasonable to expect a similar size distribution pattern for manganese from automotive sources. This would explain the strong association between MN and PB in the factor analyses reported here. This probably also explains the association of MN (TSP samples) with several factors at low loadings, rather than with a single factor as the TSP samples would include the mass of respirable as well as coarse manganese. When the concentration of the tracers in coarse particles (calculated as the differences in concentration between the TSP and RSP samples) were included with the RSP data for factor analysis, a factor on which 20% of the total variance (No. 5, Table I) was loaded was obtained. 

Figure 9.38, for example, shows the application of the chemical mass balance approach to the fine particle fraction of particles collected at a location in Philadelphia (Dzubay et at., 1988 Olmez et al., 1988 Gordon, 1988). If the set of equations (II) fitted the data perfectly, the sum of the contributions of the various sources would be 100% for each element. Clearly, from the top frame, this is not the case for a number of elements, and both positive and negative deviations from 100% can be seen. However, the contributions of several sources are clear Si and Fe from soil, Ni, V, and Ca from oil-fired power plants, Ti from a paint pigment plant, La, Ce, and Sm from a catalytic cracker, K, Zn, and Sn from an incinerator, Sb from an antimony roaster, and Pb and Br from motor vehicles. 

FIGURE 9.38 Example of chemical mass balance approach applied to fine particle fraction in Philadelphia in 1982 (adapted from Gordon, 1988). 

Ammonium nitrate, found primarily in the fine-particle fraction, results principally from the atmospheric reaction of HN03 with NH3 according to the equilibrium... 

Size-resolved analyses show that these compounds, being products of gas-to-particle conversion processes, are predominantly found in the fine particle fraction. This makes them highly susceptible to long-range transport. 

The fine particle fraction of MSA did not significantly exceed 50% of the total MSA, except at the highest flight level. A remarkably parallel behavior of the DMS and MSA profiles was observed in the mixed layer and the lower free troposphere. It is likely that both DMS and MSA concentrations were predominantly of local origin at these altitudes. The relatively strong correlation between both profiles, as compared to the nss-SC>42 profile, suggests that DMS was mainly oxidized to MSA and/or that it was converted much more rapidly to MSA than to nss-SC 2 at lower flight levels. 

Because of the nature of the enrichment process during combustion, potential tracer elements such as As, Se, and I are more enriched on fine than on coarse particles. Therefore, analyzing the fine particle fraction of source emissions and ambient aerosols increases the source-discriminating power of receptor models. 

Aqueous and ethanolic formulations have been employed with the Respimat and the in vitro aerosol performance determined. Zierenberg (1999) reported fine-particle fractions of 66% for an aqueous fenoterol formulation and 81% for an ethanolic flunisolide formulation. The respective MMADs were 2.0 0.4 pm for the aqueous formulation and 1.0 0.3 pm for the ethanolic formulation [284],... 

Another reason for using excipient carrier is to improve the availability of fine drug particles in the aerosol cloud. Surface texture of excipients appears to play a prominent role. The fine particle fraction of... 

Besides surface texture, excipient particle size also plays an important role in the fine particle generation as shown by budesonide, where the highest fine particle fraction was obtained with small-sized (<32pm) lactose as the carrier. Additionally, fine particle excipients such as fine lactose or polyethylene glycol were reported to improve the performance of carrier-based protein dry powder aerosols.However, there are some cases where carriers improved total powder emission but reduced the percent of active powders in the aerosol. To be useful carriers, the excipients must be physically stable. The important physicochemical characteristics for drug carrier selection are discussed in Ref.t f... 

In vitro experimental data show that the fine particle fraction (<5.0pm) ranged from 70% to 80%i of the device output, and the coefficient of variation for the dose output was 6% at a preset dose of 63 mg of 1% NaF solution.f The device was also evaluated in vivo using healthy volunteers and asthmatics, and the coefficient of variations were 11% for the healthy volunteers and 21%i for the asthmatics. 

Fig. 15 shows the drug mass recovered from the various stages of the impactor and device at a nominal drug dose of 75 pg per actuation. The amount of drug deposited on each stage was used to calculate the MMAD and GSD. The calculated MMAD was 2.85 pm with a GSD of 1.6. The fine particle fraction (FPF) of the aerosol was 90% (<5.8 pm) of the emitted dose, and 95% (<5.8 pm) of the dose distal to the USP throat. 

Total concentrations of silica and alumina in the fuel were 1.4 wt.% and O.S wt.% respectively (both values imply substantial soil contamination of the fuel, predominantly the wood fuel). Recoveries are good given the high silica and alumina concentrations of the bed media. Titanium, phosphorus and iron were mostly found in the coarse ash fraction and in the particle fraction of the stack flow. Alkaline-earth and alkali metals in the bed are primarily indicative of the fuel ash remaining in the bed. Substantial fractions of these elements were captured in the coarse ash fractions removed in the horizontal pass and by the cyclone, although about 10% is associated with the fine particle fraction passing the cyclone. Yields for all elements on the deposit probes are low due to the low deposit masses. 

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