Validating AIM-Based Instrumentation and Associated Measurement Techniques - Good Cascade Impactor Practices, AIM and EDA for Orally Inhaled Products - page 321

Large particle mass (LPM) and Small Particle Mass (SPM) as characterised by
rNGI, NGI and FSI

60.0

LPM
SPM

50.0

40.0

30.0

20.0

10.0

0.0

NGI FSI

rNGI NGI rNGI FSI

Compon ent B

Component A

Fig. 10.46 SPM (equivalent to FPM <5.0μm ) and LPM (equivalent to FPM >5.0μm ) determined for a
DPI simultaneously delivering two components with different MMAD values evaluated by Daniels
and Hamilton at a nominal flow rate of 60 L/min ( From [ 46 ]— used with permission )

Pressure profiles, Impactor set-ups

− 3

− 2.5

− 2

NGI
FSI

rNGI

− 1.5

− 1

− 0.5

0

0 1 2 3 4 5

Time (s)

Fig. 10.47 Pressure drop-elapsed time profiles for a DPI simultaneously delivering two compo-
nents with different MMAD values evaluated by Daniels and Hamilton at a nominal flow rate of
60 L/min ( From [ 46 ]— used with permission )

Hamilton made the important observation that these differences are likely to be
significant in determining the efficiency of the size-fractionation process; and there-
fore, the ratio of small (fine) to large (coarse) particle mass, because they occur
during the critical period of the flow-time profile when powder aerosolization, is