Sensitive quantification of 5F-NNEI and characterization of its several metabolites in authentic urine and/or serum specimens obtained from three individuals by LC–QTRAP-MS/MS and high-resolution LC–Orbitrap-MS/MS

Abstract

A synthetic cannabinoid 5F-NNEI and its metabolites in authentic human specimens have not been reported yet. The aim of this study is, firstly, to establish a sensitive quantification method of 5F-NNEI in human serum and urine specimens, and, secondly, the characterization of its metabolites in authentic urine specimens obtained from three individuals. These compounds were extracted from β-glucuronide-hydrolyzed and unhydrolyzed urine and/or serum specimens via liquid-liquid extraction. The identification and quantification were performed using liquid chromatography (LC)–QTRAP tandem mass spectrometry (MS/MS), and the characterization of the metabolites was done using LC–high-resolution-MS/MS. The limits of detection for unchanged 5F-NNEI were 6 pg/mL with the quantification range of 10–2000 pg/mL in serum, and 3 pg/mL with the quantification range of 5–1000 pg/mL in urine. The devised method was applied to quantify 5F-NNEI in authentic serum and/or urine specimens from three individuals. The levels of 5F-NNEI were 11.6 and 3680 pg/mL in serum specimens of cases 1 and 2, respectively, and were 5.07 and 7.90 pg/mL in urine specimens of cases 2 and 3, respectively. Several metabolites of 5F-NNEI produced by amide hydrolysis, defluorination, hydroxylation, carboxylation and/or glucuronization were tentatively identified in the urine specimens by the LC–high-resolution-MS/MS. A synthetic cannabinoid, 5F-NNEI, was identified and quantified in its unchanged form, and its several metabolites were tentatively identified in authentic specimens obtained from three individuals, for the first time to our knowledge.