Graphene-based gel electromembrane extraction coupled with modified screen-printed carbon electrode for detecting...

This paper presents a greener methodology for the first time to determine streptomycin in honey based on the modification of gel in the gel electromembrane extraction (G-EME) technique using exfoliated graphene (EG). Differential pulse voltammetry (DPV) with a modified screen-printed carbon electrode was used as a detection technique. The EG was prepared by applying an electrochemical exfoliation of pencil graphite as an environmentally friendly and simple method. EG has conductivity properties, large specific surface areas, and the possibility of noncovalent π-π stacking. The addition of EG to G-EME could enhance the extraction efficiency by increasing the transfer rate of streptomycin, resulting in better LOQ. Out of several materials tested (AuNPs, AgNPs, graphene oxide, graphite, EG of pencil graphite 6B), EG powder of 6B was the best nanomaterial for carrying out G-EME. Furthermore, the problem associated with increasing electric current and electroendosmosis due to addition of graphene-based nanomaterial has been totally solved by tuning the acceptor phase's volume. Under the optimal conditions to perform EG@G-EME and DPV in the honey matrix, a good linearity was obtained between 20 and 580 μg kg^-1 (R² > 0.9964) with LOD and LOQ equal to 4.9 and 16.4 μg kg^-1, respectively, in the honey matrix. Inter- and intra-assay results showed relative standard deviations of about 5 %. Compare to the conventional G-EME, our developed method showed better sensitivity.