Novel reductive-reductive mode electrochemical detection of Rohypnol following liquid chromatography and its determination in coffee

Honeychurch, Kevin C.; Davidson, Gwen M.; Brown, Emma; Hart, John P.

Abstract

© 2014 Elsevier B.V. Rohypnol (flunitrazepam) has been successfully determined in coffee by high performance liquid chromatography dual electrode detection (LC-DED) in the dual reductive mode. Initial studies were performed to optimise the chromatographic conditions and these were found to be 50% acetonitrile, 50% 50mM pH 2.0 phosphate buffer at a flow rate of 0.75mLmin-1, employing a Hypersil C18, 5μm, 250mm×4.6mm column. Cyclic voltammetric studies were made to ascertain the redox behaviour of Rohypnol at a glassy carbon electrode over the pH range 2-12. Hydrodynamic voltammetry was used to optimise the applied potential at the generator and detector cells; these were identified to be -2.4V and +0.8V for the redox mode and -2.4V and -0.1V for the dual reductive mode respectively. A linear range of 0.5-100μgmL-1, with a detection limit of 20ngmL-1 was obtained for the dual reductive mode. Further studies were then performed to identify the optimum conditions required for the LC-DED determination of Rohypnol in beverage samples. A convenient and rapid method for the determination of Rohypnol in beverage samples was developed using a simple sample pre-treatment procedure. A recovery of 95.5% was achieved for a sample of white coffee fortified at 9.6μgmL-1 Rohypnol.

• Journal Article Type: Article
• Acceptance Date: Sep 19, 2014
• Online Publication Date: Sep 22, 2014
• Publication Date: Jan 1, 2015
• Deposit Date: Dec 8, 2014
• Publicly Available Date: Mar 2, 2016
• Journal: Analytica Chimica Acta
• Print ISSN: 0003-2670
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 853
• Pages: 222-227
• DOI: https://doi.org/10.1016/j.aca.2014.09.033
• Keywords: liquid chromatography dual electrode detection, drug facilitated assault, cyclic voltammetry, beverages, Rohypnol
• Public URL: https://uwe-repository.worktribe.com/output/839714
• Publisher URL: http://dx.doi.org/10.1016/j.aca.2014.09.033
• Additional Information: Additional Information : Published in the journal Analytica Chimica Acta: http://www.sciencedirect.com/science/journal/00032670
• Contract Date: Mar 2, 2016