Comment by zephen

> One path is certainly examining the sample, which is largely discussed in the article by looking at ratios of isomers.

The trend is for the unwanted L-isomer to be mostly eliminated. That doesn't really let you know the process. Other chemical markers are used for this:

"Reductive amination remains the preferred synthetic manufacturing route for methamphetamine with 98.4% of the MPP samples analyzed profiled as originating from a P2P precursor. Approximately 9% (n=62) of these P2P-based samples showed evidence of being synthesized to methamphetamine under Leuckart conditions. This process uses methylamine and formic acid or N-methylformamide as supporting chemicals. This percentage is a slight increase compared to CY 2022 seizures (~6%). In addition, the MPP has been monitoring the Mercury Amalgam sub-classification with approximately 2% of seizures (n=14) observed to have been synthesized under these conditions and an additional 1% (n=7) of sample profiles showing markers for both Leuckart and Mercury Amalgam reactions, indicating the mixing of finished products at some point during the postproduction process."

(from https://www.dea.gov/sites/default/files/2025-09/CY%202023%20...)

> Another path to "knowing how it was made" is examining the manufacturing facilities.

That's obviously not always possible. But the entire point of the discussion above is that law enforcement has a lot of samples and tests a lot of samples, so they are in a good position to understand what has changed.

Markers they found include formic acid and mercury. Neither of those would be particularly good for you to inhale.