Carbon paper as a promising sensing material: Characterization and electroanalysis of ketoprofen in wastewater and fish.

In the present work, the exceptional electrochemical properties of carbon paper were characterized and explored in the development of a sensor for the anti-inflammatory drug, ketoprofen. An initial electrochemical characterization of the carbon paper with a redox indicator revealed much higher voltammetric peaks in comparison with other carbon-based electrodes, namely, screen-printed carbon electrode, boron-doped diamond electrode, glassy carbon electrode, pyrolytic graphite electrode, and pencil graphite electrode, predicting a good sensing performance. Ketoprofen showed a pronounced cathodic peak around -1.1 V vs Ag/AgCl (KCl, 3 M) at pH 5 in Britton-Robinson buffer, presenting a diffusion-controlled process. An optimized differential pulse voltammetry procedure was employed for ketoprofen determination achieving a limit of detection of 0.11 ± 0.01 μM, a linearity up to 6.02 μM, and a high sensitivity of 24 ± 4 or 35 ± 3 μA μM-1 cm-2 (depending on the calibration range: 0.088-1.96 μM or 1.96-6.02 μM, respectively) with acceptable (6-15% relative standard deviation) reproducibility and repeatability considering the challenging conditions of its detection in aqueous solutions. The sensor revealed to be highly selective in the presence of common interferents and other widely consumed anti-inflammatory drugs. Moreover, the developed sensor reached good accuracy in wastewater and fish samples with recoveries varying from 82.3 ± 4.4 to 88.6 ± 4.5%.