Thanks for suggestions, but I can't use it directly, firstly because it's quite old, and secondly it is unlikely I will buy some as I do not have a permission from the supervisor (I'm using it to try a single completely new procedure in order to bypass one other known procedure which is not working).
I found a notice on purification in Chai, Armarego "Purification of Laboratory Chemicals" which is more of a Reference guide for experts, and it just gives a brief note without any examples of exact quantities, and this gives quite a headache to a novice. It's even more confusing when they say it should be "redistilled from calcium hydride", and they give no indications about the quantities.