Electrochemical Nicotine Sensing in Industrial and Handmade Cigarettes Mediated by a Reduced Graphene Oxide/Silver–Copper–Hexacyanoferrate Optimized Composite

In Brazil, grocery stores and local markets commonly sell handmade cigarettes crafted from cornhusk and treated tobacco. Once a regional tradition, these artisanal cigarettes are now the second most consumed type in the country. Tobacco products contain nicotine (NIC), a highly addictive substance linked to cardiovascular diseases. This study presents an electrochemical synthesis method for a reduced graphene oxide/silver–copper–hexacyanoferrate (rGO/AgCuHCF) composite, optimized for sensitive NIC detection. The optimized material is prepared using a 3:1 Ag:Cu ratio in an initial cyclic voltammetry step, followed by treatment with a pH = 7.0 ferricyanide solution, achieving a sensitivity of 13.0 nA L mol⁻¹ via a 2² factorial design experiment. Microscopic analysis reveals uniformly distributed PBA particles over the wrinkled carbon support, while spectroscopic and diffraction techniques confirm distinct bimetallic PB analogue structural features from monometallic variants. Batch injection analysis-assisted amperometry with the rGO/AgCuHCF-modified electrode exhibits a linear current response for NIC between 5.0 and 2000.0 μmol L⁻¹, achieving a superior sensitivity of 32.9 nA L mol⁻¹ and a low detection limit of 0.9 μmol L⁻¹. This sensor demonstrates viability and reliability for NIC detection in industrial and artisanal cigarettes tobacco samples.