Thats a good idea you can send samples to independant testing labs that will run them through a mass spectronomer and gas chromatograph, it can be expencive or sometimes as cheap as about $35 per test, the equipment can detect very very small quantittys and I wouldnt suggest sending them very much as they may report it to law enforcement, in most cases though they dont unless it turns out to be Plutonium, I dont know of any in the UK but I'm sure an online search may turn up a few.
I have some lab reports on a few brand name gear I'd be happy to send ya, mostly on British Dragon gear.