PMID: 11337159May 5, 2001Paper

On the difficulty of assessing the specific surface area of magnesium stearate

International Journal of Pharmaceutics
C AndrèsY Pourcelot

Abstract

The water content of as-received commercial magnesium stearate batches from animal and vegetable sources have been modified by ageing in humid air at room temperature or by vacuum treatment. The complete adsorption-desorption isotherms of nitrogen and krypton vapours by samples of these as received and modified materials have been measured at liquid nitrogen temperature after standardised vacuum degassing. They are greatly affected by the initial water content of the material. In particular: (a) the BET surface area values computed from the adsorption branch vary widely and is increasing with increasing water content; (b) anomalous hysteresis of varying amplitude is observed in all cases except adsorption of krypton on the material with the lowest water content; (c) the hysteresis loops extend down to very low desorption pressure values and cannot be accounted for by capillary condensation. Lastly, the surface area value of a given material computed from nitrogen and krypton adsorption may differ by a factor as high as six. Accordingly, the very significance of BET surface area values obtained from routine adsorption experiments should be regarded as questionable, at least until the mechanisms of adsorption are fully clarified.

References

Dec 1, 1992·Journal of Pharmaceutical Sciences·U I LeinonenE S Laine
Jul 1, 1988·Journal of Pharmaceutical Sciences·K D Ertel, J T Carstensen

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Citations

Aug 21, 2003·International Journal of Pharmaceutics·Pierre BracconiAugustin Ndiaye
Feb 7, 2012·Drug Development and Industrial Pharmacy·Patrick OkoyeRutesh H Dave
Mar 21, 2008·Journal of Pharmaceutical Sciences·Mazen L HamadMansoor A Khan
Mar 12, 2005·European Journal of Pharmaceutics and Biopharmaceutics : Official Journal of Arbeitsgemeinschaft Für Pharmazeutische Verfahrenstechnik E.V·I Bravo-OsunaM R Jiménez-Castellanos
Dec 5, 2014·Saudi Pharmaceutical Journal : SPJ : the Official Publication of the Saudi Pharmaceutical Society·Janine BoniattiHelvécio Vinícius Antunes Rocha
Jun 3, 2005·Chemical & Pharmaceutical Bulletin·Robert Roskar, Vojko Kmetec

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