Amazonian tucumã-seed biochar as a high-performance electrochemical modifier for quinoline detection in waste samples

Abstract Amazonian fruit biomass was used to obtain tucumã biochar, an inorganic material and electrochemical modifier that later was used as one of three components to fabricate a novel voltammetric sensor. Aiming for the determination of quinoline in industrial effluents, the modified carbon paste ratio of 40:30:30 (w/w/w) graphite:tucumã biochar:binder was selected due to a significant increase of 94% in I cp when compared with the unmodified CPE. Analytical calibration curves to quantify the analyte and assess matrix effects (ME), demonstrated high linearity across three effluents, with r2 values of 0.994, 0.996, and 0.992, respectively. Detection limits (LODs) for effluents 1, 2, and 3 were 3.28, 2.48 and 8.26 nmol L −1 , respectively, while quantification limits (LOQs) were 5.46, 0.37 and 1.22 nmol L −1 , reflecting the method’s high sensitivity. Characterisation studies (SEM, FTIR, BET, CV and DPV) of the biochar indicate an amorphous material, high volume of functional groups, low specific surface area, and high electroactive surface area. Recoveries ranging from 98 to 100% were achieved for effluents 1 to 3. Repeatability and reproducibility tests yielded relative standard deviation (RSD%) values under 5%, and the MCPE/TB demonstrated good inter-day stability (RSD < 4%). These findings confirm the promising use of highly functionalised tucumã seed biochar as an electrochemical modifier. Graphical abstract