[daseiner1]

I was under the impression that it's impossible to reliably test, e.g., cocaine for fentanyl, without destroying the drug and it doesn't take much of the latter narcotic to kill you.

[jampekka]

The amount that has to be destroyed is miniscule.

[daseiner1]

my point is that powders don't mix evenly. part of a baggie testing negative for fentanyl doesn't mean the remainder is clean.

[sitkack]

Then thoroughly mix the whole amount before taking a sample.

[cstrahan]

Given that a lethal dose of fentanyl is about two milligrams (similar to 5-7 grains of table salt in volume), that still feels pretty risky.