Ethylenediamine and its derivatives are causing two problems when determining their water content: they can shift the pH of the medium in the titration vessel towards the alkaline range if the amount of sample is large enough, and they can cause a receding end point due to secondary side reaction taking place in media containing methanol.
Based on results of our tests we do not recommend coulometric titration. Suitable are the methanol-free volumetric reagents Hydranal-Composite 5 and Hydranal-Working Medium K. To neutralize the amines, it is very important that the amount of benzoic acid recommended in the Procedure is used.
According to the latest findings, Hydranal-Working Medium K is classified as very toxic. Instead of that Hydranal-Buffer Base can be used.
Download the full Laboratory Report for Ethylenediamine Derivatives (L 026) here
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Honeywell Research Chemicals