Analysis of 13 fentanils, including sufentanil and carfentanil, in human urine by liquid chromatography-atmospheric-pressure ionization-tandem mass spectrometry.

A sensitive, semiautomated method for the analysis of several fentanils and fentanil metabolites in human urine is described. This method uses solid-phase extraction of urine samples followed by liquid chromatography-atmospheric pressure ionization-tandem mass spectrometry. Isotopically labeled internal standards were included for 6 of the 13 analytes in this study. Estimated detection limits ranged from 3 to 27 pg/mL, and good accuracy and long-term precision were observed in most cases. This method should be useful for the rapid and sensitive screening of human urine samples for a number of fentanils and their metabolites as indicators of exposure.