Lab Drug Checking and Positional Isomers: 2-, 3-, or 4-MEC

This last week, a sample was submitted and analyzed through EcstasyData that we clearly established was one of the three main ring-positional isomers of Methylethylcathinone (aka MEC). However, we didn’t have the lab standards on hand for this chemical, because it is the first time we’ve run into it since the supplier of lab standards we order from has stocked the three positional isomers.

Based on library matches* alone, it was impossible to be certain whether the sample contained 2-MEC, 3-MEC, or 4-MEC. We’ve run into this issue of positional isomers a bunch of times before over the last sixteen years of operating our street drug analysis project.

Luckily, Cayman Chemicals is a really great source of lab standards for NPS (“new psychoactive substances” aka psychoactive research chemicals). So we ordered reference standards for 2-MEC, 3-MEC, and 4-MEC, to find out if our equipment and lab procedures could make use of having the actual verified isomers on hand, for the purpose of confirming whether sample #5682 contained one or more of these slightly different versions of the same parent compound.

We ordered the standards on September 5th and they arrived at Drug Detection Laboratories (the lab that EcstasyData contracts with) on the 7th. The amazing DDL lab team, working on Saturday, ran the standards through their GC/MS and were able to confirm that sample #5682 contains only 4-Methylethylcathinone and none of the other two positional isomers. Yay!

There are many psychoactive chemicals with positional isomers that are difficult to reliably differentiate using GC/MS or UV absorption, even with the proper standards on hand. We’ve spent a lot of time over the last few years seeking clarity in our analysis of fluorinated amphetamines (2-, 3-, or 4-Fluoroamphetamine aka 4-FA) and the *-APB chemicals. And we’ve not been entirely successful. In most cases, one of the positional isomers is easy to tell apart from the others, but the other versions overlap in complex ways by retention time or fragmentation patterns. For MEC, the differences in column retention times for each of the positional isomers make them easy to differentiate using DDL’s Agilent GC/MS.

On another note, we also ordered a lab standard for Benzyl fentanyl this week, and were able to confirm that sample #5667 contains only Benzyl fentanyl. Less impressive, since we were pretty certain that’s what it was to begin with, but the initial match was based on comparing against other published spectra and not our own lab’s confirmation using a known standard of the same substance.

by Earth & Sylvia



*Identifying “by library match” refers to the process of comparing images of GC/MS output for a given sample to images of GC/MS output for a verified reference standard. Because equipment and lab procedures vary, to double-check identification by library match, a lab can acquire its own sample of a reference standard (if one is available), run it through the lab’s equipment, and compare the resulting images to those of the submitted sample being analyzed.

Leave a Reply

Your email address will not be published. Required fields are marked *