Electrochemical detection of oxytetracycline employing sugarcane carbon modified graphite electrode

The present study used CeO₂-Co₃O₄ quantum dots@porous carbon/multiwalled carbon nanotube (CeO₂-Co₃O₄ QDs@PC/MWCNT/GE) composites to modify graphite electrodes to fabricate high-sensitivity electrochemical sensors to detect the presence of oxytetracycline (OTC). The quantum dots were made from waste sugarcane bagasse. The electrochemical analysis demonstrated the superior electrochemical performance of CeO₂-Co₃O₄ QDs@PC/MWCNT/GE, with a peak current density of 1.276 mA/cm². Electrochemical impedance spectroscopy (EIS) revealed lower impedance values for CeO₂-Co₃O₄ QDs@PC/MWCNT/GE compared to other electrodes, indicating enhanced conductivity. The modified electrode exhibited an enlarged electrochemically active area, with values of 0.602 cm², almost seven times that of the bare graphite electrode (0.079 cm²). The results showed that the CeO₂-Co₃O₄ QDs@PC/MWCNT/GE had excellent performance for OTC detection, and its linear calibration range was 1.007 × 10^-8 to 2.04 × 10^-7 M (i.e., 0.005-0.1 ppm) and 1.007 × 10^-6 to 1.209 × 10^-4 M (i.e., 0.5-60 ppm). The limit of detection and limit of quantification were 1.23 nM (0.61 ppb) and 4.09 nM (2.03 ppb) (S/N = 3), respectively. The electrode demonstrated long-term stability for up to 7 weeks. This method provides a new way to prepare electrochemical sensors for OTC detection.