British Journal of Anaesthesia, 1982, Vol. 54, No. 5 561-565
© 1982 The Board of Management and Trustees of the British Journal of Anaesthesia
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MECHANISMS OF HALOTHANE ADSORPTION BY DRY SODA-LIME
Department of Anesthesiology, Columbia University New York, New York, U.S.A
Department of Chemical Engineering, University of Connecticut Storrs, Connecticut, U.S.A.
Department of Anesthesiology, University of Connecticut Farmington, Connecticut, U.S.A
*Present address for correspondence: Columbia-Presbyterian Medical Center, New York, New York 10032, U.S.A.
Using fresh soda-lime (15% water by weight) the soda lime/air partition coefficient of halothane was found to decrease as a function of vapour phase halothane concentration from 2 40 at 0.3% halothane by volume to 1.15 at 2.6percnt;, but adsorption generally followed Henry's law. However, soda-lime dried to a constant weight and subsequently exposed to various concentranons of halothane adsorbed approximately 320 µlitre of vaporized liquid halothane per 100 g before a measurable concentration of halothane was detected in the vapour phase. Adding additional halothane then caused a linear increase in vapour concentration. We conclude that dry soda-lime can adsorb large quantities of halothane by a mechanism which is nimilar to that of a molecular sieve. After these "high affinity" sites are satisfied, additional halothane is adsorbed by a mechanism following Henry's law.