2019-02-13/14 Lyophilization Summit Prague. Geoff Smith. Podium Presentation
2019-03-17T23:13:42Z (GMT) by
Podium presentation by Geoff Smith at the Lyophilization Summit in Prague, February 13-14th 2019, describing the application of through vial impedance spectroscopy in the determination of nucleation temperatures and solidification end points.
TVIS dielectric loss parameters Fpeak and Cpeak appear to offer the opportunity for the registration of the primary nucleation whereas the dielectric storage at low frequency (eg 10 or 100 Hz) allow for the registration of secondary ice nucleation (ie ice growth). In addition the dielectric storage at high frequency (eg 200 kHz) shows little temperature sensitivity and so is an ideal measurement frequency for assessing the end point of ice solidification. Post solidification, the parameter log Fpeak can then be redeployed to determine the point at which all excess latent heat has left the sample and the product temperature then equilibrates with the shelf. This work paves the way for the determination of a new critical process parameter based on the time interval between ice growth onset and ice solidification end point (alongside the ice nucleation temperature).