AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Bipolar Charge Measurement for DPI (Dry Powder Inhaler) Particles
JONNA KANNOSTO, Ville Niemelä, Henna Isherwood, Jaakko Yli-Ojanperä, Jorma Keskinen, Risto Hillamo, Anna Frey, Steve Layzell, David Prime, Ari Ukkonen, Dekati Ltd., Tampere, Finland
Abstract Number: 628 Working Group: Instrumentation and Methods
Abstract Recently, delivery of various drugs to lungs has been of increased scientific interest and it has become a more and more common way to treat different diseases, not only respiratory diseases like asthma. According to computer simulations, electrostatic deposition of inhaler drug particles dominates in the lower lung regions (Balachandran et al. 1997), particularly in the alveoli where the most efficient systemic absorption exists. Earlier charge studies have focused on particle net charge measurements (Telko et al. 2007) since a method for measuring bipolar charge has not been available.
The Dekati® Bipolar Charge Analyzer (BOLAR™) is the first commercial instrument available for measuring aerosol particles’ bipolar electrical charge as a function of particle size. The instrument separates negatively and positively charged particles in 5 size fractions in electrical collection tubes. After the measurement, the electrical collection tubes can be uncoupled and positive and negative particles can be recovered and analyzed separately. Thus, the bipolar charge in respect of mass can be assigned as well as the particles’ composition in different size ranges.
In this presentation, the detailed operating principle and calibration results including impactor stage collection efficiencies, the tube collection efficiencies and the flow divider penetration are shown. The quality of flow dividing has been studied by net charges and analyzing the amount of particles in each branch. The particle deposition (losses) in different parts of the instrument has also been studied in detail.
The BOLAR™ was used together with ELPI™ (Electrical Low Pressure Impactor) to determine size distribution and net charge of lactose particles. The results from the two instruments show good correlation for both size and net charge data. Furthermore, the BOLAR™ results show high bipolar charge levels of lactose particles indicating inadequacy of net charge measurements when studying charging behavior of DPI particles.
Balachandran et al.(1998), J. Electrostat, 579, 40-41
Telko et al.(2007),International journal of pharmaceutics, 336, 352-360