SQUARE-WAVE VOLTAMMETRIC DETERMINATION OF CARBENDAZIM ON A 3D-PRINTED BASED SENSOR MODIFIED WITH BIOCHAR FROM COFEE HUSKS

In this work we propose a novel 3D-printed based sensor modified with biochar for the determination of the fungicide carbendazim in natural waters using square wave voltammetry (SWV). The biochar (BC) was produced from the pyrolysis of coffee husks [1], an agro-industrial waste with significant potential for environmental pollution. The 3D-printed based sensor was prepared through the coating of an insulating 3D-printed substrate (ring shape printed by Acrylonitrile Butadiene Styrene - ABS) with a modified homemade conductive (acetone, BC from coffee husks, graphite-G and ABS). G-ABS or BC-G-ABS, Ag|AgCl|KCl_sat. And Pt (working, reference and counter electrodes, respectively) were assembled in a miniaturized 3D-printed electrochemical cell [2]. The conductive paint with 10 % wt. of biochar (pyrolyzed at 300 ^oC / 50 min) provided the best carbendazim detectability. The geometric and electroactive areas of this BC-G-ABS were 0.1256 and 0.1934 cm², respectively. Using this BC-G-ABS under the optimized conditions of SWV, a linear range of 0.25 to 15 µmol L^-1 (R= 0.998), LOD of 50 nmol L⁻¹ and LOQ of 180 nmol L⁻¹ were obtained. Good inter-electrode reproducibility was obtained (RSD = 6.21%; n=6), showing a good manufacture efficiency. Good precision was obtained for intra and inter-day (RSD = 2.7 and 7.0 %; n = 10). An addition-recovery study was performed in water samples (drinking and river) spiked with known concentrations of carbendazim, in which was obtained good accuracy (between 93 and 96 %). These results show the potentiality of biochar from coffee husks as a green modifier of 3D-printed-based electrodes for the determination of carbendazim and other electroactive contaminants in environmental samples.