The opioid crises has prompted the interest of many providers in the capabilities of urine drug testing (UDT) to detect fentanyl analogs (FA). However, the most frequently used methods for clinical UDT are not designed to broadly screen for the variety of FAs that may be encountered. Using the knowledge that fentanyl and many FA fragment to common product ions of m/z=105 and m/z=188, we developed and tested a semi-targeted UDT for FA using precursor ion scan (PIS) mode.
The objective of this study was to assess the performance of a liquid chromatography tandem mass spectrometry (LC-MS/MS) PIS method to screen for a variety of FA in an adult urine.
94 residual adult urine specimens were screened for the presence of fentanyl and 6 FA using PIS. A Waters Xevo TQD tandem mass spectrometer was configured to acquire data in positive mode on all precursor ions 200-400 Da triggered by the detection of product ions m/z=188 and m/z=105. Data was post-processed to evaluate extracted ion chromatograms that correspond to known FA masses, including precursor ions of m/z=281 (4-ANPP), m/z = 323 (Acetylfentanyl), m/z=335 (Acrylfentanyl), m/z= 337 (Fentanyl), m/z=351 (Butyrylfentanyl), m/z=369 (4-FIBF), and m/z= 375 (Furanylfentanyl). Presumptive positivity was assigned based on visual assessment of chromatograms and estimated retention time windows for each FA. Performance of the PIS method was assessed by comparison to a targeted LC-MS/MS method for fentanyl and acetylfentanyl (addition of other FAs to the targeted profile is in progress).
Relative to the targeted assay, the sensitivity of the PIS screen was 91% and 100% for fentanyl and acetylfentanyl, respectively. The specificity of the PIS method for fentanyl was 97% while acetylfentanyl specificity was 95%. The accuracy of PIS was 94% for fentanyl and 96% for acetylfentanyl. Although not yet verified, 1 presumptive positive for acrylfentanyl and 7 specimens containing 4-ANPP were also identified by PIS. Interestingly, all specimens tentatively positive for FA were concurrently positive for fentanyl. In addition, all presumptive 4-ANPP identifications were observed in samples confirmed positive for acetylfentanyl. On-going studies include assessment of PIS relative to targeted LC-MS/MS, method optimization to decrease detection limits/reduce isobaric interferences, and expanding data review to screen for additional FA.
Preliminary results suggest that semi-targeted screening for FA by PIS is a viable option for discovering previously undetected compounds in adult urine, however studies to assess the performance characteristics of this method are on-going. This novel approach to UDT has potential implications for public health surveillance and improved patient care in toxicological evaluations. We envision application of the PIS screen as a tool to identify FA present in our community which could be added to our targeted LC-MS/MS UDT.