Targeted screening and quantification of synthetic cathinones and metabolites in hair by UHPLC-HRMS

Synthetic cathinones (SCs) are new psychoactive substances with sympathomimetic effects, which emerged into the illegal drug market to replace controlled stimulants. Since every year more powerful and toxic substances enter the illicit market, there is the need for analytical methodologies able to detect these new compounds in conventional and non-conventional biological matrices. We sought to develop and validate a targeted screening and quantification method for thirty-two parent SCs and two metabolites in hair samples by ultra-high-performance liquid chromatography coupled to high resolution mass spectrometry (UHPLC-HRMS).

20 mg hair samples were soaked in 250 µL of 2 mM ammonium formate, methanol and acetonitrile mixture (50/25/25, v/v/v) and incubated overnight at 40°C. After incubation, the samples were evaporated to dryness under nitrogen stream and reconstituted with 100 µL of mobile phase mix (A:B, 80:20) and 10 µL were injected into UHPLC-HRMS. A Q ExactiveTM Focus Orbitrap Mass spectrometer with full scan and targeted data-dependent MS/MS scan acquisition was used for the screening and quantitation analysis.

The assay was linear from 5 to 500 pg/mg hair for all the analytes under investigation. Intra-day and inter-day precision were always < 15% and matrix effect and analytical recovery were always within acceptable criteria (±25% and >50%, respectively). The developed method was applied to authentic hair samples from SCs consumers. The most prevalent found SCs were 3,4-Methylenedioxy-α-Pyrrolidinohexanophenone with a concentration range of 6.0-1,000.0 pg/mg along with α-Pyrrolidinohexiophenone (54.0 and 554.0 pg/mg, respectively), 3-Methylmetcathinone (556.0 and 5,000.0 pg/mg) and 4-Methylethcathinone (11.5 and 448.0 pg/mg) CONCLUSIONS: The developed method showed good selectivity, specificity, an easy and low-cost sample preparation and an analysis time compatible with a high throughput laboratory.