Cascade impactors characterization

Cascade Impactors in the Chemical and Physical Characterization of Coal-Combustion Aerosol Particles... 

Sampling. Sampling practices play an important role in particle size characterization using cascade impactors. Short-duration sampling may result in unrepresentative size estimates [74]. This is also the case for anisokinetic sampling [19]. 

Figure 12 Aerodynamic particle size characterization techniques using (A) Andersen eight-stage nonviable cascade impactor and (B) four-stage liquid impinger.

Cascade impactors are typically characterized based on the nozzle geometry, number of stages, flow rate capacity, and the range of effective cut-off diameters of the impaction stages. Characteristics of some most commonly used cascade impactors are exemplified in Table 2.1. 

Denyer J. Breathing patterns in adult patients. J Aerosol Med 1997 10(1) 99. Stapleton KW, Finlay WH. Errors in characterizing nebulized particle size Distributions with cascade impactors. J Aerosol Med 1998 ll(Suppl l) 80-83. 

A comparative study of the spray-dried nanoparticulate budesonide versus micronized budesonide was performed Each powder was blended with lactose and then filled into a Clickhaler (ML Laboratories) DPL and the aerodynamic diameters of the dehvered powders were characterized on an Andersen eight-stage cascade impactor. The results, which are summarized grcq)hically in the following section, show that the MMAD of the nanoparticulate aggregate aerosol was much smaller than the MMAD of the micronized drug aerosol. A substantial fraction of... 

---