Multilayer graphene–gold nanoparticle hybrid substrate for the SERS determination of metronidazole

• SERS substrate based on multilayer graphene and AuNPs.
• Simple, rapid and reproducible synthesis of substrate.
• SERS hybrid substrate applied to the determination of metronidazole.

In this paper, a simple, quick and reproducible SERS substrate combining the properties of multilayer graphene (≈ 4 layers) and gold nanoparticles has been developed. The Raman signal of metronidazole is enhanced at a factor of 124 when deposited on the hybrid substrate enabling its determination at low concentrations. The five most relevant added values of the paper as regards other similar proposed procedures are: i) better sensibility, ii) good reproducibility, iii) rapidity, iv) reusability and v) instrumental simplicity. The procedure presented is capable of detecting and quantifying small quantities of metronidazole without implying any preconcentration step, just using an affordable and portable Raman spectrometer. The LOD and LOQ achieved with this hybrid substrate were 1.1 and 3.68 mg L− 1 of the analyte. The use of graphene provides high reproducibility to the SERS active hybrid substrate. The RSD was 7.76% within a substrate and 10.92% between substrates. The developed SERS active hybrid substrate can be reused without loss in sensitivity.