Objective: To provide options for industry to calibrate impactors in an effective manner.
Status: Project initiated. To support this activity it was suggested that impactor group participants should contribute towards a photo library of typical issues observed with failing/defective impactors. The impactor group could then collate a failure log for impactors to help identify common failure modes.
Objective: Support Pharmacopeial development of GCIP and understand sources of variability in the CI measurement process.
Status: Project initiated. Initial work has identified synergies with IPAC/RS and therefore team will ensure there is no duplication and clarity between the two efforts. The EPAG team will concentrate on supportive practical work to demonstrate GCIP/variability in CI testing and recommendations for hands on improvements. This group will also follow pharmacopeial development and updates closely to ensure robust, fit-for-purpose and science based impactor methods in pharmacopoeias. The group are in the process of discussing comments to be provided to IPAC-RS on the Good Cascade Impactor Practice Stimulus article.
Industry Perspective on Pressure Drop Measurement (NM)
NM provided an update at work conducted at Vectura to support Darryl’s investigations, and provided an industry perspective on using ΔP measurements for in-use impactor monitoring.
Vectura are currently gathering data on their in-use NGI’s to determine whether the ΔP measurements are sensitive enough to detect atypical impactor results. They are currently awaiting mensuration of the uncleaned NGI to determine correlation of ΔP with changes in nozzle diameter.
The presentation raised the following observations:
MC/DR commented that the issue of whether impactor manufacturing tolerance limits were appropriate for in-use limits. If these could be widened would ΔP be more useful?
Objective: To provide industry guidance on AIM opportunities
Status: Project team initiated. The previous work in this area has been consolidated and separated from the EDA. A further understanding will be sought on what companies are using as AIM and at which stage of development they see most benefit. This will allow a more focussed approach on assisting industry.
EPAG poster presented at the conference. MH asked whether the poster constitutes the final report for this activity?
The group took an action to gather more information regarding which devices are in use, with a view to designing a more specific questionnaire to gauge wealth of available data, and to consider circulating the questionnaire to users outside of the impactor group (Copley may be able to help with this if we decide to explore this option). The group should also consider whether a new workshop (perhaps at a future DDL?) would be useful to present new data to a wider audience.
Objective: To use CFD on further understanding the mechanism by which inertial impactors work and how throats can affect the subsequent deposition profiles.
Status: Project team initiated. Work consolidated with Henk’s group at Nottingham. Excellent progress to date on CFD modelling which has linked in to explain some of the practical data generated in the air volume studies. Funding needs to be secured in this exciting area to support ongoing work that is very likely to assist in impactor use/design for the future. Publications of work have occurred with a DDL podium presentation.
HV gave an update presentation on current CFD modelling activities to the team, as well as prompting a discussion on possible future activities.
Modelling of particle deposition – HV reported that Steady flow model reveals complex flow distribution in single nozzle impactor and that Collection efficiency curves can be matched to data by adjusting models of turbulence and particle restitution behaviour.
Four options for future work were presented, of these option 3 - Study effect of low, medium and high resistance on transient flow through cascade impactors – was preferred.