[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.