Sensitive voltammetric determination of matrine using a nitrogen-doped graphene/zinc oxide nanocomposite modified electrode

A facile one-pot hydrothermal strategy was established to engineer a high-activity sensing interface for quantifying matrine with minimal sample pretreatment. In situ reduction/functionalization of graphene oxide together with ZnO nucleation produced a hybrid film in which nanoparticles were uniformly anchored (20–30 nm) and exhibited distinct (002) lattice fringes (d = 0.26 nm); elemental analysis indicated C 75.6%, N 4.5%, O 12.1% and Zn 7.8%. Electrochemical probing with [Fe(CN) 6 ] 3−/4− showed accelerated interfacial kinetics, decreasing ΔEp from 215 mV (bare) to 62 mV and reducing Rct from ~880 Ω to 68 Ω. The film enabled a well-defined anodic response for matrine at +0.95 V, delivering a peak current ~4.5× higher than the nitrogen-doped graphene control. Signal optimization identified pH 7.5 as optimal, with Ep shifting linearly with pH (Ep = 1.345 − 0.0582 pH, R² = 0.998), and adsorptive enrichment at open circuit saturating at 240 s. Under these conditions, pulse electroanalysis provided two linear ranges (0.05–10 μM and 10–200 μM) with Ipa = 1.85c + 0.42 (R² = 0.998) and Ipa = 0.64c + 12.61 (R² = 0.997), respectively, and a detection limit of 15 nM (3σ/S, n = 11). Precision was high (18.91 μA at 10 μM, RSD 2.1%; inter-electrode RSD 3.8%), with 94.5% signal retained after 4 weeks at 4 °C and