Fentanyl detection and quantification using portable infrared absorption spectroscopy




Ramsay, Margo

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Community drug checking is a harm reduction strategy that is currently being employed in response to the ongoing overdose crisis in North America. The Vancouver Island Drug Checking Project uses a variety of methods to analyze drug samples including fentanyl and benzodiazepine immunoassay test strips, attenuated total reflection Fourier transform infrared spectroscopy, Raman spectroscopy and gas chromatography–mass spectrometry. A study was designed to examine the combined ability of infrared spectroscopy and partial least squares regression to quantify the fentanyl content of illicit opioids. Binary and ternary mixtures of powdered fentanyl HCl, anhydrous caffeine and sugar alcohols were prepared as standards representative of the opioids samples presented for drug checking. The infrared spectra of each set of standards was used to train and test individual partial least squares regression models. A grid search was employed to optimize the number of latent variables and data pre-processing strategy for each model. A robust partial least squares regression model, trained on all four sets of standards, was shown to accurately quantify fentanyl content. This model was then used to evaluate the fentanyl concentration of samples brought in for drug checking. In the period October 2018 to December 2020, the detected level of fentanyl in opioid samples had a mean concentration of 10% with a standard deviation of 7%. Illicit opioids which contained caffeine hydrate were discovered upon examination of the anomalous service samples that were identified by local outlier factor. The infrared spectrum of caffeine shows subtle changes upon its hydration, which are due to differences in the hydrogen bonding pattern of the two forms of caffeine. Standards containing semi-hydrated caffeine and fentanyl HCl were prepared and analyzed to explore the effect of caffeine hydration on fentanyl quantification.



fentanyl, harm reduction, infrared absorption spectroscopy