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Dissolution Discussion Group Bulletin Board > Dissolution Discussion (post in the DDG forum) > Hydrochloric acid PDA
View Full Version : Hydrochloric acid
evj
08-08-2002, 09:25 AM
Can anyone explain to me why the USP description for Hydrochloric acid, 1 N (solutions/volumetric solutions) p. 2349 describes 85 ml of HCl, which do not result in 1 N (36,46 g/1000ml), when using fuming HCl, 37%, density of 1.19 g/ml....85ml gives a solution of 1,027 N. In order to reach 1 N by using 85 ml, the HCl used must be 36%, which is out of the range stated for HCl in USP (36,5-38%).
SPMayock
08-19-2002, 10:08 AM
evj, This is a great point. This is one of the few places in the general sections that give you a preparation for 1.0 N HCl which could be used to scale to 0.1N HCl for dissolution medium. Generally the pharmaceutical companies that I have worked for have not used the volumetric solution preparation method for 0.1 HCl dissolution medium because it is not accurate. I have seen some variations in the preparation method for 0.1N HCl including using the VS method. It would be interesting to poll the DDG on the exact preparation method that they employ for 0.1N HCl and propose that this concensus method be added to the reagent section of the USP for 0.1N HCl dissolution medium so that we all are using the same volumes without the slight variations that exist today. Does anyone else have a thought on this? Steve