which buffer need to autoclave, which can not - (Apr/08/2005 )

this question is basic, but i had never got cleared.
Which kind of buffer usually need to be autoclaved. what buffer can not or if which reagent in the buffer, the buffer can not be autoclaved, otherwise the reagent will be damaged?

Thanks

off the top of my head I have been told MgSO4 can not be autoclaved.

most other solutions can I would say.

Nick