Specifically the gas chamber. I have an idea for a story (it might have been inspired by an existing story, so please post if it sounds familiar) were people are allowed to commit suicide voluntarily via gas chamber so their organs can be donated.

Conventional gas chambers produce cyanide gas. Does this leave the organs contaminated and therefore unusable? What about lethal injection? It seems the overdose of barbiturates would leave a residue in the organs that might be harmful to the recipient of the donated organ.

Any knowledge about this, anyone?