Current approaches to APSD measurements of OIPs based on inertial impaction

Abstract

The AIM and EDA concepts are founded on the principles of inertial impaction of aerosol particles under laminar flow conditions. This chapter examines the current CI systems that are recognized by the pharmaceutical compendia, providing a summary of the key parameters that affect the size-resolving capability of each system. The potential for bias introduced through the assumption that individual stage collection efficiency curves are step functions at the calibration size is explored, with attention given to the effect of removing stages in order to achieve an AIM-based configuration. Non-sizing accessories, such as the induction port (IP) entry and preseparator (PS), are discussed and the chapter concludes with consideration of how add-on devices, such as spacers and VHCs that are commonly used in conjunction with MDIs, should be evaluated.