Molecularly imprinted electrochemical sensor based on poly(3,4-ethylenedioxythiophene)/carboxylated biochar for ceftiofur estimation in milk

This work presents use of agricultural waste-derived biochar as a functional substrate for MIP-based electrochemical sensing of ceftiofur sodium. Herein, carboxylated biochar derived from rice straw was deposited onto fluorine-doped tin oxide (FTO) electrode, followed by in situ electro-polymerization of a ceftiofur sodium-imprinted PEDOT layer on its surface, forming the MIP/COOH-biochar sensing interface. The optimized MIP sensor displayed a broad linear response range (1 ng mL − 1 − 10 5 ng mL − 1 ), with a detection limit of 0.03 ng mL − 1 . Moreover, the MIP sensor demonstrated selective recognition of ceftiofur sodium, with an imprinting factor of 4.23, excellent reproducibility (RSD < 2.236%), and good sensitivity, as indicated by the slope of the calibration plot ( I pa vs. log C), which was 72.6 µA log − 1 (ng mL − 1 ). Practical applicability was confirmed through spike-recovery studies and analysis of real milk samples. Among six commercial milk samples tested, ceftiofur sodium was detected in two samples, and the results were validated with the LC-MS technique, confirming the suitability of the constructed MIP sensor for real sample analysis.