What microplastics are, and what µFTIR, Raman, and Py-GC-MS actually measure.
The term is 20 years old and still doesn't have one universal size cutoff — here's the definition this Standard actually uses.
None of the three methods used in the MPFREE Standard measures the same thing. Here's the actual difference.
A lab can report "non-detect" on a sample that still contains nanoplastics — because most methods were never designed to see them.