Hey i'm not sure about the tests you posted but when you make bho it all evaporates when you're heating it. If it didn't your oil would catch fire when you lit it.

Some butane has impurities like RONSON. Don't use this brand. The best brand to use is Colibri. Has no impurites at all.

Also, i use a glass turkey baster for my bho. Stainless steel and glass is pretty much the best thing you can use. I can't see how butane would strip anything from plastic though? Maybe if it was painted plastic.