Post #2357443
2026-04-26 15:30 UTC
@timmc@better.boston 2/2 Plus, deriving an acutal concentration from the XRF return, instead of just a yes/no would require careful technique. I guess you could take a sample, put it in a plastic cup in some reproducible geometry, mix+measure 3 times, add 1 shot of a known concentration of lead nitrate, mix+measure 3 more times, add a second shot, mix+measure 3 times, fit a line on the lead peak heights vs. lead shot, then use that to estimate how much was in there originally. (standard addition method)
Replies (1)
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@timmc@better.boston 2026-04-26 15:35
@Methylzero@mast.hpc.social Ah, that makes sense! One thing I'd been wondering is how you would get a concentration without knowing the denominator. Soil is largely going to be light elements that the detector can't even see. :-/ So the addition method would allow per-sample mass calibration. That's pretty cool, but slow, and produces lead-contaminated waste. Though I wonder if I could use a less toxic addition? It wouldn't calibrate on lead specifically, but might help with concentration overall.