Assessment of two brands of fentanyl test strips with 251 synthetic opioids reveals “blind spots” in detection capabilities

Abstract

Background Fentanyl test strips (FTS) are a commonly deployed tool in drug checking, used to test for the presence of fentanyl in street drug samples prior to consumption. Previous reports indicate that in addition to fentanyl, FTS can also detect potent fentanyl analogs like acetyl fentanyl and butyryl fentanyl, with conflicting reports on their ability to detect prominent fentanyl analogs like carfentanil and furanyl fentanyl. Yet with hundreds of known fentanyl analogs, there has been no large-scale study rationalizing FTS reactivity to different fentanyl analogs. Methods In this study, 251 synthetic opioids- including 214 fentanyl analogs- were screened on two brands of fentanyl test strips to 1) assess the differences in the ability of two brands of fentanyl test strips to detect fentanyl-related compounds and 2) determine which moieties in fentanyl analog chemical structures are most crucial for FTS detection. Two FTS brands were assessed in this study: BTNX Rapid Response and WHPM DanceSafe. Results Of 251 screened compounds assessed, 121 compounds were detectable at or below 20,000 ng/mL by both BTNX and DanceSafe FTS, 50 were not detectable by either brand, and 80 were detectable by one brand but not the other (n = 52 BTNX, n = 28 DanceSafe). A structural analysis of fentanyl analogs screened revealed that in general bulky modifications to the phenethyl moiety inhibit detection by BTNX FTS while bulky modifications to the carbonyl moiety inhibit detection by DanceSafe FTS; we hypothesize that the different “blind spots” may be caused by different haptens used to elicit the antibodies for these different strips. Conclusions By utilizing both brands of FTS in routine drug checking, users could increase the chances of detecting fentanyl analogs in the “blind spot” of one brand.

Elucidating the Gas-Phase Behavior of Nitazene Analog Protomers Using Structures for Lossless Ion Manipulations Ion Mobility-Orbitrap Mass Spectrometry

“…(1) relatively simple technologies like test strips 9,10 and (2) advanced technologies that employ sophisticated analytical instrumentation like Raman spectroscopy, 8,11 mass spectrometry (MS) and/or tandem mass spectrometry (MS/MS), 12−18 and ion mobility spectrometry (IMS). 19−22 Test strips (colorimetric and immunoassay-based) are fast, cheap, and easy to use, but they are chemically specific.…”

“…Test strips may also yield false positives when testing mixtures in which other compounds are present with NSOs 10 or false negatives as they may not detect all the possible analogs of a class of NSOs. 9 Alternatively, the advanced technologies are nonspecific and can be used to analyze many different NSOs simultaneously. MS is one of the most widely used advanced techniques for detecting NSOs due to its low limits of detection, fast analysis speed, and readiness for coupling with orthogonal separation techniques like liquid chromatography (LC).…”