[refurb]

This doesn't sound like a solution at all.

It went from "pointing a gun at an item" to "concentrating a sample".

I've done analytical chemistry before and sampling accurately is not a trivial thing.

[kragen]

It probably isn't important whether the lead content is 10 ppm or 20 ppm in most cases, since neither is acceptable, so the standard of sampling involved here is far less demanding than the standard of sampling needed for analytical chemistry. You just need to avoid contaminating your sample with lead from some other source.