The way you mitigate this is by using negative samples. Basically blank swabs/tubes/whatever that don't have the substance you're testing in it, but that is han

The way you mitigate this is by using negative samples. Basically blank swabs/tubes/whatever that don't have the substance you're testing in it, but that is handled the same way. Then the tested result is Actual Sample Result - Negative Sample Result. So you'd expect a microplastic sample to have 2,000 plus N per mm^2, and N is the result of your test.