Effect of Water on Degradation of Propantheline Bromide mixed with Dried Aluminum Hydroxide Gel

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Effect of humidity and water content on the degradation of propantheline bromide mixed with dried aluminum hydroxide gel was examined. Degradation of propantheline bromide in this system is accelerated with increasingly higher humidity until under 75% RH and decreased under more high humidity, and was the most marked when 0.2 ml of water was added per 5 g of the mixture. Degradation became slower as the amount of water added became greater or smaller than that. Addition of 0.2 ml/5 g of water means that water molecule forms a monolayer on the surface of dried aluminum hydroxide gel. Since the gel used orginally contained 4% of water, addition of 0.2 ml/5 g means that two layers of water molecule were formed on the surface of the gel. Degradation of propantheline bromide is most marked when water molecule forms a monolayer to several layers on the surface of the gel. This degradation was assumed to be initiated through the layer on the surface of dried aluminum hydroxide gel.