Rapid identification of cyclopropyl fentanyl/crotonyl fentanyl in clinical urine specimens: A case study of clinical laboratory collaboration in Canada

- An LC/MS precursor ion scan strategy was used to detect unknown fentanyl analogues.
- Cyclopropyl fentanyl and a metabolite were tentatively identified by high-resolution MS.
- The drug was identified in up to 5% of fentanyl screen-positive urine samples.
- Levels were often comparable to those of fentanyl.