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How Good Are the Data? Novel Metric Assesses Probability That an Unknown Drug Sample Matches a Known Sample

NCJ Number
Date Published
March 2022

This web article presents National Institute of Justice-supported research into the identification of seized drugs; specifically, novel psychoactive substances, opioids, and opiates.


There is a silent race happening right now, between those who create novel, potentially harmful substances and those who make the laws regarding the legality of these substances. Legal guidelines are dependent on even the most minor changes in the molecular structure of these types of compounds, including synthetic cannabinoids and drugs designed to mimic the effects of fentanyl. The identification of seized drugs often relies on gas chromatography and mass spectrometry. In light of the proliferation of novel psychoactive substances, as well as opioids and opiates, National Institute of Justice-supported researchers sought to create an objective quantitative metric for the identification of seized drugs. This metric could estimate the amount of variation found within the mass spectra and the likelihood of being a match to a reference library sample’s spectrum. The focus of the research described in this article was to establish a minimum threshold, to determine if a library match can be successfully applied in light of this variability.

Date Published: March 1, 2022