Voltammetric Determination of Carbendazim Using a Biochar Modified 3D-Printed Based Sensor

3D printing has been benefiting electroanalysis due to the quick and low-cost manufacture of cells and sensors. For this production, the choice of eco-friendly materials is welcome due to the agreement to the principles of sustainability, green chemistry, and circular economy. In this work a novel 3D-printed sensor modified with biochar (BC) from coffee husk residues is proposed for the determination of the fungicide carbendazim in natural waters using square wave voltammetry (SWV). The sensor was prepared through the coating of an insulating ring-shaped 3D-printed substrate (Acrylonitrile Butadiene Styrene/ABS) with a BC-modified conductive ink (acetone, ABS, graphite, and BC). Using the optimized sensor (10% wt. of BC) in 0.1 mol L⁻¹ phosphate buffer (pH 2.0) and optimized SWV parameters (E_s = 2 mV, f = 15 Hz and A = 120 mV), the detectability of carbendazim was 50% higher than unmodified, and a linear range (LR) from 0.25 to 15.00 µmol L⁻¹ (R² = 0.998) and a limit of detection (LOD) (S/N = 3) of 50 nmol L⁻¹ were obtained. Good inter-electrode (RSD = 6.21%; n = 6) and inter-day (RSD = 6.96%; n = 10) reproducibility and accuracy (recovery between 92.71% and 96.43% in water samples) were obtained. This alternative sensor is simpler than those fabricated using BC-modified filaments, being promising for the trace level analysis of environmental pollutants.