Point-Of-Care Drug-Checking: Assessing the Rhode Island Drug Supply Using FTIR Spectroscopy to Detect Fentanyl, Xylazine and Other Substances

Abstract

Introduction: The illicit drug supply constantly fluctuates, with new adulterants and unexpected mixtures creating uncertainty. Point-of-care drug-checking services are vital in reducing overdose risk and other harms by providing real-time analysis, harm reduction education and links to care. This study aimed to characterise the local drug supply using Fourier transform infrared (FTIR) spectroscopy, complemented by Liquid Chromatography-Quadrupole time-of-flight Mass Spectrometry (LC-QToF-MS) for additional context, from drug residues collected through a drug-checking program within a Rhode Island harm reduction site. Methods: From January to May 2023, 100 samples were analysed using FTIR and sent for additional qualitative and semi-quantitative testing via LC-QToF-MS. Substances detected by both methods were summarised by prevalence, mixture composition and alignment with self-reported drug categories. Results: Fentanyl (53%) and cocaine (48%) were the most prevalent substances detected by FTIR, followed by xylazine (10%) and methamphetamine (8%). Cross-category analysis revealed cocaine in 36% of opioid-reported samples and fentanyl in 3% of self-reported cocaine samples, underscoring the mixed nature of the supply. We found the local fentanyl supply (n = 57) showed high variability, with 15 additional components detected by FTIR, including xylazine (19.3%). Discussion and Conclusions: These findings provide a snapshot of the unpredictable and highly mixed nature of the Rhode Island drug supply defined by stimulant-opioid overlaps, xylazine adulteration and the presence of cocaine across drug categories. By pairing real-time FTIR with laboratory-based analysis, we provided actionable information back to service users while also uncovering deeper patterns in local drug trends.