Good Cascade Impactor Practices - Good Cascade Impactor Practices, AIM and EDA for Orally Inhaled Products - page 98

Fig. 4.4 A CI method failure investigation tree ( Adapted from [ 3 ]— used by permission )

developed thus far meet the needs of regulatory agencies to provide data that are
unambiguous in terms of both recovered API mass and aerodynamic diameter [ 77 ].
This situation, however, may change, as API-specific measurement techniques,
such as Raman spectroscopy, are combined with microscopy-image analysis, as a
means of quantifying particle size distributions for systems comprising compact,
near-to-spherical particles. In such circumstances, the dynamic shape factors ( ) are

close to unity, making it possible to approximate to the aerodynamic diameter scale
from microscopy-measured circle/volume-equivalent diameter ( d v ), provided that
the particle density is close to unity (see Chap. 2 ) .

χ

4.3.2 The Potential in CI Methodology Simplification

The advantages of CI method simplification become obvious when the number of
operations associated with a typical eight-stage full-resolution CI measurement
(Fig. 4.5 shows the situation for the ACI as an example system) is compared with