Novel electrical impedance methods in formulation and process development. Podium presentation at Freeze-Drying Technology Summit, Vienna 13-14 Feb 2020

This presentation provides a brief introduction to electrical impedance and dielectric relaxation processes in liquid and frozen aqueous solutions, before discussing the use of micro-scale measurements in a freeze-drying microscope (highlighting potential applications for formulation screening).

These microscale studies are based on a single analytical instrument (Z-FDM) which combines impedance (Z) spectroscopy with freeze-drying microscopy (FDM) with an interdigitated micro-electrode array placed on a freeze-drying microscope stage.

Critical process parameters of ice growth, sublimation drying rate and end-point were demonstrated using the Z-FDM technique.

A brief overview of in-vial measurements in a freeze-dryer (using through-vial impedance spectroscopy) is also given, along with the statements on potential applications for process development.