Application of through vial impedance spectroscopy (TVIS) for the determination of ice nucleation, solidification endpoint, and mannitol crystallization and melt-back temperature during freezing and annealing.Poster presentation at ISL-FD 9th International Conference 2-6th September, 2019, Ghent, Belgium
Longinus Ogugua
Geoff Smith
Ahmet Orun
10.21253/DMU.9759497.v2
https://figshare.dmu.ac.uk/articles/conference_contribution/Application_of_through_vial_impedance_spectroscopy_TVIS_for_the_determination_of_ice_nucleation_solidification_endpoint_and_mannitol_crystallization_and_melt-back_temperature_during_freezing_and_annealing/9759497
<p>Studies of the
freezing behavior of aqueous solutions of mannitol are highly relevant to
lyophilization process development given the prevalent use of this excipient.
Here, through-vial impedance spectroscopy (TVIS) was used to study the
behaviour of an aqueous solution of 5%w/v mannitol during a freezing and
re-heating cycle. Temperature calibration of the TVIS parameter F<sub>PEAK</sub>
enabled the determination of the ice nucleation temperature T<sub>n</sub> at
−13 <sup>o</sup>C while the ice solidification end point was observed based on
the time profile of C' (0.2MHz), i.e. the real part capacitance at 0.2 MHz. A
time difference of 20 min between the onset and end point then defines the ice
solidification time t<sub>i</sub>. A later step in C^' (0.2MHz) indicated that
mannitol crystallized at -32 <sup>o</sup>C and 20 minutes from end of ice
solidification. Upon reheating at 0.2 <sup>o</sup>C/min, a large increase in C'
(0.2MHz) was seen at −32 <sup>o</sup>C indicating the onset of melting of
mannitol crystals which then lasted 20 min.</p>
2019-09-25 11:57:34
freeze-drying method
TVIS
Lyophilization,
nucleation site
Pharmaceutical technology
Pharmaceutical Sciences