TG/MS capillary interface

May, Joan C.; Grosso, Alfred V. Del; Wheeler, R.M.; Etz, Nora M.

doi:10.1007/bf01996778

Cited by 5 publications

(2 citation statements)

References 5 publications

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“…These values are consistent with the typical water contents of spray-dried protein powders that are in the 2-5% range and those of lyophilized cakes that are in the 0.1-0.3% range. 3,4,16 For both rhG-CSF and rConIFN powders the water content increases to 5-8% after exposure to 33% RH and to 9 -19% after exposure to 75% RH (Table I), respectively. This is also relatively independent of the trehalose content.…”

Section: Influence Of Moisture On Protein Conformationmentioning

confidence: 95%

Fourier transform infared spectroscopy investigation of protein conformation in spray‐dried protein/trehalose powders

French

Arakawa

2004

Biopolymers

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Spray drying is a way to generate protein solids (powders), which is also true for lyophilization. Sugars are used to protect proteins from conformational changes and chemical degradations arising from drying processes and storage conditions such as the humidity. The influence of trehalose and humidity on the conformation and hydration of spray-dried recombinant human granolucyte colony stimulating factor (rhG-CSF) and recombinant consensus interferon-alpha (rConIFN) was investigated using Fourier transform IR spectroscopy. The spectral analysis of spray-dried powders in the amide I region demonstrated that trehalose stabilized the alpha-helical conformation of both rhG-CSF and rConIFN proteins. Exposure of the pure protein powders to 33% relative humidity (RH) resulted in the formation of beta sheets and loss of turns but no change in alpha-helical structure. Trehalose reduced the magnitude of the changes in beta sheets and turns. Exposure of the pure protein powders to 75% RH resulted in the loss of alpha-helical conformation with a corresponding increase in beta structures (beta sheets and turns). Trehalose did not protect proteins from the loss of alpha-helical structures, but it reduced the formation of antiparallel beta sheets. Hydrogen-deuterium exchange (H-D exchange) was used to further characterize these hydration-induced conformational changes. At 33% RH the percent exchange of the protein decreased with increasing trehalose content, indicating a greater protection of the protein from H-D exchange by a higher concentration of trehalose. Such protection correlates with decreased conformational changes of the protein by trehalose at this humidity. At 75% RH the degree of H-D exchange of the protein was insensitive to the powder composition in all powders. Surprisingly, the H-D exchange of trehalose was low at about 20-25%, which was nearly independent of the protein/trehalose ratio and humidity, indicating that the exchangeable protons on trehalose molecules are highly protected in protein-containing powders. The observed protein hydration is related to the effect of trehalose on the conformational changes of the protein under humidity.

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Section: Influence Of Moisture On Protein Conformationmentioning

confidence: 95%

Fourier transform infared spectroscopy investigation of protein conformation in spray‐dried protein/trehalose powders

French

Arakawa

2004

Biopolymers

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“…The technique is routinely used to characterise materials that exhibit mass gain or loss caused by decomposition, oxidation or dehydration. It is particularly useful in the measurement of water contents [104], especially where only small amounts of sample are available or if it is not compatible with the Karl-Fischer medium [167,168]. The disadvantage of TGA is that it determines mass changes but it cannot identify the nature of the evolved species.…”

Section: Thermogravimetric Analysismentioning

confidence: 99%

Thermoanalytical Techniques for the Investigation of the Freeze Drying Process and Freeze-Dried Products

Kett¹,

Mcmahon²,

Ward³

2005

CPB

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A key challenge facing the pharmaceutical industry is the production of biotechnological drug products such as proteins in a stable form. Freeze-drying is preferred for manufacturing such products because of the low temperatures used. However, the protein may still degrade during the process necessitating the inclusion of a protectant. This review describes the range of thermal analysis techniques that have been used to investigate the properties of formulations to be freeze dried and the resultant products. This approach has allowed insight into the key parameters required for design of formulations and processes that will generate the best possible products.

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