Evaluating the Impact of Operating Temperature and Humidity on Bipolar Charge Measurements using the Dekati BOLAR
Cheng Pang1, Melanie Hamilton1, Justyna Nalepa-Grajcar1, David Prime1, Ed Taylor1
1Drug Product Design & Development, GlaxoSmithKline R&D, Park Road, Ware, Hertfordshire, SG12 0DP, United Kingdom
This study investigated measurement robustness of the Dekati bipolar charge analyser or BOLARTM, specifically the influence of operating temperature and humidity on bipolar charge measurements using a range of aerosolised inhalation powders.
The Dekati BOLAR is the first commercially available unit capable of measuring the bipolar charge of aerosolised material as a function of particle size. To enhance understanding of the subtle relationships between bipolar electrostatic charge and temperature/humidity, one must first understand the capabilities and optimal operating conditions of the BOLAR in order to make accurate and scientifically sound interpretation of the charge data generated.
The data from this study demonstrated that bipolar charge measurements were generally consistent and reproducible across a temperature and humidity range encompassing typical laboratory conditions; temperature ranging from 19 to 27°C with a relative humidity (RH) range of 10 to 54%.
The experiment provided confidence that bipolar charge measurements were insensitive to variations in operating conditions, therefore any observed differences between aerosols may be attributed to the material under test. Furthermore, each formulation tested exhibited unique bipolar charge characteristics with differing overall net charge and bipolar charge magnitude which remained consistent throughout the study.