Cargando…

Observations on the Changing Shape of the Ice Mass and the Determination of the Sublimation End Point in Freeze-Drying: An Application for Through-Vial Impedance Spectroscopy (TVIS)

Models for ice sublimation from a freeze-drying vial rely on the assumption of a planar ice interface up to ~25% loss of ice mass (which is difficult to qualify) whereas single-vial determinations of the sublimation endpoint (by temperature sensors) are based on the point when the observed temperatu...

Descripción completa

Detalles Bibliográficos
Autores principales: Pandya, Bhaskar, Smith, Geoff, Ermolina, Irina, Polygalov, Evgeny
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8624880/
https://www.ncbi.nlm.nih.gov/pubmed/34834255
http://dx.doi.org/10.3390/pharmaceutics13111835
_version_ 1784606281853566976
author Pandya, Bhaskar
Smith, Geoff
Ermolina, Irina
Polygalov, Evgeny
author_facet Pandya, Bhaskar
Smith, Geoff
Ermolina, Irina
Polygalov, Evgeny
author_sort Pandya, Bhaskar
collection PubMed
description Models for ice sublimation from a freeze-drying vial rely on the assumption of a planar ice interface up to ~25% loss of ice mass (which is difficult to qualify) whereas single-vial determinations of the sublimation endpoint (by temperature sensors) are based on the point when the observed temperature reaches a plateau, which cannot differentiate between sublimation and desorption-drying. In this work, the real part capacitance of TVIS vial(s) containing frozen water (during sublimation drying) was measured at 100 kHz. This parameter [Formula: see text] was shown to be highly sensitive to the shape and volume of the ice mass and is therefore a useful parameter for monitoring ice sublimation. By placing a digital camera in front of an isolated TVIS vial containing ice, it was possible to relate the changes in the shape of the ice mass with the changes in the trajectory of the time profile of [Formula: see text] and determine the point of deviation from a planar ice interface and ultimately determine the point when the last vestiges of ice disappear. Thereafter, the same characteristics of the [Formula: see text] time-profile were identified for those TVIS vials located out of sight of the camera in a separate full-shelf lyo study, thereby obviating the need for photographic examination.
format Online
Article
Text
id pubmed-8624880
institution National Center for Biotechnology Information
language English
publishDate 2021
publisher MDPI
record_format MEDLINE/PubMed
spelling pubmed-86248802021-11-27 Observations on the Changing Shape of the Ice Mass and the Determination of the Sublimation End Point in Freeze-Drying: An Application for Through-Vial Impedance Spectroscopy (TVIS) Pandya, Bhaskar Smith, Geoff Ermolina, Irina Polygalov, Evgeny Pharmaceutics Article Models for ice sublimation from a freeze-drying vial rely on the assumption of a planar ice interface up to ~25% loss of ice mass (which is difficult to qualify) whereas single-vial determinations of the sublimation endpoint (by temperature sensors) are based on the point when the observed temperature reaches a plateau, which cannot differentiate between sublimation and desorption-drying. In this work, the real part capacitance of TVIS vial(s) containing frozen water (during sublimation drying) was measured at 100 kHz. This parameter [Formula: see text] was shown to be highly sensitive to the shape and volume of the ice mass and is therefore a useful parameter for monitoring ice sublimation. By placing a digital camera in front of an isolated TVIS vial containing ice, it was possible to relate the changes in the shape of the ice mass with the changes in the trajectory of the time profile of [Formula: see text] and determine the point of deviation from a planar ice interface and ultimately determine the point when the last vestiges of ice disappear. Thereafter, the same characteristics of the [Formula: see text] time-profile were identified for those TVIS vials located out of sight of the camera in a separate full-shelf lyo study, thereby obviating the need for photographic examination. MDPI 2021-11-02 /pmc/articles/PMC8624880/ /pubmed/34834255 http://dx.doi.org/10.3390/pharmaceutics13111835 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Pandya, Bhaskar
Smith, Geoff
Ermolina, Irina
Polygalov, Evgeny
Observations on the Changing Shape of the Ice Mass and the Determination of the Sublimation End Point in Freeze-Drying: An Application for Through-Vial Impedance Spectroscopy (TVIS)
title Observations on the Changing Shape of the Ice Mass and the Determination of the Sublimation End Point in Freeze-Drying: An Application for Through-Vial Impedance Spectroscopy (TVIS)
title_full Observations on the Changing Shape of the Ice Mass and the Determination of the Sublimation End Point in Freeze-Drying: An Application for Through-Vial Impedance Spectroscopy (TVIS)
title_fullStr Observations on the Changing Shape of the Ice Mass and the Determination of the Sublimation End Point in Freeze-Drying: An Application for Through-Vial Impedance Spectroscopy (TVIS)
title_full_unstemmed Observations on the Changing Shape of the Ice Mass and the Determination of the Sublimation End Point in Freeze-Drying: An Application for Through-Vial Impedance Spectroscopy (TVIS)
title_short Observations on the Changing Shape of the Ice Mass and the Determination of the Sublimation End Point in Freeze-Drying: An Application for Through-Vial Impedance Spectroscopy (TVIS)
title_sort observations on the changing shape of the ice mass and the determination of the sublimation end point in freeze-drying: an application for through-vial impedance spectroscopy (tvis)
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8624880/
https://www.ncbi.nlm.nih.gov/pubmed/34834255
http://dx.doi.org/10.3390/pharmaceutics13111835
work_keys_str_mv AT pandyabhaskar observationsonthechangingshapeoftheicemassandthedeterminationofthesublimationendpointinfreezedryinganapplicationforthroughvialimpedancespectroscopytvis
AT smithgeoff observationsonthechangingshapeoftheicemassandthedeterminationofthesublimationendpointinfreezedryinganapplicationforthroughvialimpedancespectroscopytvis
AT ermolinairina observationsonthechangingshapeoftheicemassandthedeterminationofthesublimationendpointinfreezedryinganapplicationforthroughvialimpedancespectroscopytvis
AT polygalovevgeny observationsonthechangingshapeoftheicemassandthedeterminationofthesublimationendpointinfreezedryinganapplicationforthroughvialimpedancespectroscopytvis