Design and fabrication of Punica granatum peel-derived NSCQD/iron hexacyanoferrate ternary composite for simultaneous detection of ascorbic acid, uric acid, and resorcinol

This work reports the synthesis of a novel paraffin-impregnated graphite electrode (PIGE) modified by N- and S-doped carbon quantum dot (NSCQD)/iron hexacyanoferrate composite for the electrochemical detection of resorcinol (RS), uric acid (UA), and ascorbic acid (AA). Using pomegranate (Punica granatum) peel as the carbon source, the NSCQDs were synthesized in an environmentally friendly manner. When combined with FeHCF, the NSCQDs formed a high-performance composite with enhanced electrochemical properties. The morphology, crystallinity, and chemical composition of the composite were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS) analysis, respectively, which revealed a structure that was clearly defined and contained active spots that were suitable for redox reactions. Electrochemical tests revealed the sensor’s high sensitivity, measuring 523.4 mA/mol/L for AA, 451.22 mA/mol/L for UA, and 372.1 mA/mol/L for RS. The sensor has low limits of detection of 2 × 10−6 mol/L, 3 × 10−6 mol/L, and 5 × 10−6 mol/L for AA, UA, and RS, respectively, with a linear detection range of 10 × 10−6 mol/L to 8000 × 10−6 mol/L for all analytes. Superior conductivity was brought about by the addition of graphene, redox activity was increased by FeHCF, and enhanced adsorption and catalysis were achieved by the introduction of electron-rich sites by NSCQDs. The identification of AA in Limcee tablets, UA in Allopurinol tablets, and RS in hair color solutions served as examples of real-world applicability. The electrode outperformed traditional electrodes in terms of sensitivity and decreased oxidation potential, and it demonstrated outstanding stability, maintaining 95% of its performance after 50 cycles. This study demonstrates the NSC/FeHCF-modified PIGE’s potential for real-world uses in environmental monitoring, pharmaceutical quality assurance, and clinical diagnostics.