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14. Implementation of a Process Analytical Technology system in a freeze-drying process using Raman spectroscopy for in-line process monitoring

Author

De Beer, T.R.M., Alleso, M., Goethals, F., Coppens, A., Vander Heyden, Y., De Diego, H. Lopez, Rantanen, J., Verpoort, F., Vervaet, C., Remon, J.P., and Baeyens, W.R.G.

Subjects
Raman spectroscopy -- Usage, Freeze-drying -- Methods, Chemistry
Abstract

The aim of the present study was to propose a strategy for the implementation of a Process Analytical Technology system in freeze-drying processes. Mannitol solutions, some of them supplied with NaCl, were used as models to freeze-dry. Noninvasive and in-line Raman measurements were continuously performed during lyophilization of the solutions to monitor real time the mannitol solid state, the end points of the different process steps (freezing, primary drying, secondary drying), and physical phenomena occurring during the process. At-line near-infrared (NIR) and X-ray powder diffractometry (XRPD) measurements were done to confirm the Raman conclusions and to find out additional information. The collected spectra during the processes were analyzed using principal component analysis and multivariate curve resolution. A two-level full factorial design was used to study the significant influence of process (freezing rate) and formulation variables (concentration of mannitol, concentration of NaCl, volume of freeze-dried sample) upon freeze-drying. Raman spectroscopy was able to monitor (i) the mannitol solid state (amorphous, [alpha], [beta], [delta], and hemihydrate), (ii) several process step end points (end of mannitol crystallization during freezing, primary drying), and (iii) physical phenomena occurring during freeze-drying (onset of ice nucleation, onset of mannitol crystallization during the freezing step, onset of ice sublimation). NIR proved to be a more sensitive tool to monitor sublimation than Raman spectroscopy, while XRPD helped to unravel the mannitol hemihydrate in the samples. The experimental design results showed that several process and formulation variables significantly influence different aspects of lyophilization and that both are interrelated. Raman spectroscopy (in-line) and NIR spectroscopy and XRPD (at-line) not only allowed the real-time monitoring of mannitol freeze-drying processes but also helped (in combination with experimental design) us to understand the process.

Published
2007

27. Ethenylene-bridged periodic mesoporous organosilicas with ultra-large mesopores

Author

Vercaemst, C., de Jongh, P.E., Meeldijk, J.D., Goderis, B., Verpoort, F., van der Voort, P., Heterogene katalyse en oppervlakteonderzoek, Inorganic Chemistry and Catalysis, Sub Inorganic Chemistry and Catalysis, and Dep Scheikunde

Abstract

E-configured ethenylene-bridged periodic mesoporous organosilicas with ultra-large mesopores and unprecedented pore volumes have been developed for the first time.

Published
2009

28. Periodic mesoporous organosilicas consisting of 3d hexagonally ordered interconnected globular pores

Author

Vercaemst, C., Friedrich, H., de Jongh, P.E., Neimark, A.V., Goderis, B., Verpoort, F., van der Voort, P., Heterogene katalyse en oppervlakteonderzoek, Inorganic Chemistry and Catalysis, and Sub Inorganic Chemistry and Catalysis

Abstract

A new family of periodic mesoporous organosilicas with 100% E-configured ethenylene-bridges and controllable pore systems is presented. 2D hexagonally ordered hybrid nanocomposites consisting of cylindrical pores are obtained, of which some are filled with solid material. The architectural composition of these hybrid materials can be accurately controlled by fine-tuning the reaction conditions; that is, there is a unique correlation between the reaction mixture acidity and the amount of confined mesopores. This correlation is related to the filling of the pores with solid material whereby the length of the pore channels can be tailored. Hereby the mesophase either shifts toward long-ranged 2D hexagonally ordered open cylinders or toward 3D hexagonally ordered interconnected spheres. The synthesis of these organic−inorganic hybrid composites is straightforward via the direct condensation of E-1,2-bis(triethoxysilyl)ethene, in the presence of pluronic P123. The true nature of these periodic mesoporous organosilicas is disclosed by means of nitrogen gas physisorption, nonlocal density functional theory, SAXS, TEM, and electron-tomography.

Published
2009

29. Isomeric periodic mesoporous organosilicas with controllable properties

Author

Vercaemst, C., Ide, I., Friedrich, H., de Jong, K.P., Verpoort, F., van der Voort, P., Inorganic Chemistry and Catalysis, Dep Scheikunde, and Sub Inorganic Chemistry and Catalysis

Abstract

The synthesis procedure for isomeric periodic mesoporous organosilicas with E-configured ethenylene bridges was investigated using the homemade pure E-isomer of 1,2-bis(triethoxysilyl)ethene. The pH, aging temperature and the presence of cosolvents played a key role in obtaining well-ordered mesoporous materials with controllable properties and morphologies. By fine-tuning the reaction mixture acidity, PMOs with high surface areas and pore volumes could be attained. By selecting various alcohols as cosolvents and optimizing the alcohol concentration, PMOs with crystal-like disc shaped, fibrous and spherical particle morphologies were obtained. The synthesis temperature of these ethenylene-bridged PMOs influences the pore size, structure, connectivity and volume.

Published
2009

30. Periodic mesoporous organosilicas consisting of 3d hexagonally ordered interconnected globular pores

Author

Heterogene katalyse en oppervlakteonderzoek, Inorganic Chemistry and Catalysis, Sub Inorganic Chemistry and Catalysis, Vercaemst, C., Friedrich, H., de Jongh, P.E., Neimark, A.V., Goderis, B., Verpoort, F., van der Voort, P., Heterogene katalyse en oppervlakteonderzoek, Inorganic Chemistry and Catalysis, Sub Inorganic Chemistry and Catalysis, Vercaemst, C., Friedrich, H., de Jongh, P.E., Neimark, A.V., Goderis, B., Verpoort, F., and van der Voort, P.

Published
2009

31. Isomeric periodic mesoporous organosilicas with controllable properties

Author

Inorganic Chemistry and Catalysis, Dep Scheikunde, Sub Inorganic Chemistry and Catalysis, Vercaemst, C., Ide, I., Friedrich, H., de Jong, K.P., Verpoort, F., van der Voort, P., Inorganic Chemistry and Catalysis, Dep Scheikunde, Sub Inorganic Chemistry and Catalysis, Vercaemst, C., Ide, I., Friedrich, H., de Jong, K.P., Verpoort, F., and van der Voort, P.

Published
2009

32. Ethenylene-bridged periodic mesoporous organosilicas with ultra-large mesopores

Author

Heterogene katalyse en oppervlakteonderzoek, Inorganic Chemistry and Catalysis, Sub Inorganic Chemistry and Catalysis, Dep Scheikunde, Vercaemst, C., de Jongh, P.E., Meeldijk, J.D., Goderis, B., Verpoort, F., van der Voort, P., Heterogene katalyse en oppervlakteonderzoek, Inorganic Chemistry and Catalysis, Sub Inorganic Chemistry and Catalysis, Dep Scheikunde, Vercaemst, C., de Jongh, P.E., Meeldijk, J.D., Goderis, B., Verpoort, F., and van der Voort, P.

Published
2009

33. Implementation of a process analytical technology system in a freeze-drying process using raman spectroscopy for in-line process monitoring

Author

De Beer, T. R. M., Allesø, Morten, Goethals, F., Coppens, A., Vander Heyden, Y., Diego, H. Lopez De, Rantanen, Jukka Tapio, Verpoort, F., Vervaet, C., Remon, J. P., Baeyens, W. R. G., De Beer, T. R. M., Allesø, Morten, Goethals, F., Coppens, A., Vander Heyden, Y., Diego, H. Lopez De, Rantanen, Jukka Tapio, Verpoort, F., Vervaet, C., Remon, J. P., and Baeyens, W. R. G.

Published
2007

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