10.21253/DMU.9759497.v2
Longinus Ogugua
Longinus
Ogugua
Geoff Smith
Geoffrey
Smith
Ahmet Orun
Ahmet
Orun
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
De Montfort University
2019
freeze-drying method
TVIS
Lyophilization,
nucleation site
Pharmaceutical technology
Pharmaceutical Sciences
2019-09-25 11:57:34
Conference contribution
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>