Use of Diagnostic Ions for the Detection of Fentanyl Analogs in Human Matrices by LC-QTOF.

To combat the ongoing opioid epidemic, our laboratory has developed and evaluated an approach to detect fentanyl analogs in urine and plasma by screening LC-QTOF MS/MS spectra for ions that are diagnostic of the core fentanyl structure. MS/MS data from a training set of 142 fentanyl analogs were used to select the four product ions and six neutral losses that together provided the most complete coverage (97.2%) of the training set compounds. Furthermore, using the diagnostic ion screen against a set of 49 fentanyl analogs not in the training set resulted in 95.9% coverage of those compounds. With this approach, lower reportable limits for fentanyl and a subset of fentanyl-related compounds range from 0.25 to 2.5 ng/mL in urine and 0.5 to 5.0 ng/mL in plasma. This innovative processing method was applied to evaluate simulated exposure samples of remifentanil and carfentanil in water and their metabolites remifentanil acid and norcarfentanil in urine. This flexible approach enables a way to detect emerging fentanyl analogs in clinical samples.