Fabrication of a new electrochemical sensor based on screen-printed carbon electrode/amine-functionalized graphene oxide-Cu nanoparticles for Rohypnol direct determination in drink sample

Rohypnol or Flunitrazepam belongs to benzodiazepines (Schedule IV) with much higher and long-lasting effects on the central nervous system. Unfortunately, it is used in suicide and aggression. Since it can eventually be detected in the urine within 72 h, it is essential to measure it quickly and accurately. In this work, a new electrochemical sensor for the Rohypnol measurement was fabricated based on a modified screen-printed carbon electrode (SPCE). The SPCE surface was modified with amine-functionalized graphene oxide sheets reinforced through Cu nanoparticles)SPCE/AGO-Cu(with an average size of 30 nm. At the SPCE surface, an oxidation peak was observed for Rohypnol at a potential of 0.30 V. However, an oxidation peak at a potential of 0.25 V with two reduction peaks were appeared for Rohypnol at the SPCE surface modified with AGO-Cu in the potential range of 0 to 1 V. The ability of the SPCE/AGO-Cu to measure Rohypnol was studied. A linear dependency was resulted between Rohypnol concentration and SPCE/AGO-Cu response in the range of 0.4–140 μM and a limit of detection (LOD) of 0.13 μM in aqueous solution. According to the results, the SPCE/AGO-Cu provides an accurate and precise assay pathway of Rohypnol in the fruit juice.