Yes for samples that contain binder/filler (hopefully) some purification is done to raise that 10%. But FTIR is speculative? do you have a source? It doesn't seem that way, there are low certainty matches and higher certainty matches. If you have ever looked at an FTIR screen you will see that some matches are so perfect in matching the reference spectrum that it doesn't make sense to pass it off as some sort of coincidence.
The second thing they do, reagent test strips, aim to address the problem of the lack of accuracy below 10%... although we really shouldn't send it to gydt for samples such as LSD and instead use multiple reagents at home and post pictures to come up with a rough verdict.
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