¹H, ¹³C, ¹⁵N HMBC, and ¹⁹F NMR spectroscopic characterisation of seized flephedrone, cut with benzocaine.

Flephedrone (4-fluoromethcathinone, 4-FMC) was analysed using (1)H, (13)C, (15)N HMBC, and (19)F observe spectroscopy, gas chromatography-flame ionisation detection (GC-FID), and electrospray ionisation-mass spectrometry (ESI-MS). Analysis of four 4-FMC samples (from a Bristol nightclub in 2013) showed that they all contained benzocaine as the cutting agent present in different amounts from 5 to 12%. Using these methods, we successfully differentiated between flephedrone regioisomers and mephedrone in an analytical method validated for flephedrone as a substituted cathinone. The data show that these now illegal cathinone-derived stimulants (highs) are now being cut; users cannot be certain of the purity of the drug they are taking. Furthermore, there are risks from the pharmaceutically active cutting agents themselves.