3D-PRINTED MINI SENSORS FOR SULFANILAMIDE DETECTION UTILIZING COMMERCIAL HYDROGEL AS AN ELECTROCHEMICAL CELL

The development of new electrochemical devices is crucial for monitoring residues of synthetic antibiotics like sulfonamides, which possess a broad antibacterial spectrum. Initially used exclusively in human medicine, sulfonamides have since been adopted in veterinary medicine and as herbicides, raising concerns about their potential to contaminate the environment. This study aims to utilize low-cost commercial hydrogels, originally intended for decorative use, as electrochemical cells for analyzing sulfanilamide (SFA) in water and pharmaceutical formulation samples. Miniature sensors were fabricated using 3D pens and conductive filaments composed of PLA and graphite (3D/PLA/Gr-ME). The sensors were characterized using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) with the [Fe(CN)₆]³⁻^/⁴⁻ redox probe (5 mmol L⁻¹).  For the analysis, the hydrogel is first immersed in the solution for at least 8 hours. After this period, it is removed, and the electrodes are inserted into the hydrogel for measurement. The influence of pH on the SFA oxidation process was assessed using a BR buffer solution (0.1 mol L⁻¹) with pH values ranging from 2.0 to 10.0, ultimately selecting pH 10.0. A square wave voltammetry (SWV) method was optimized, resulting in a linear working range of 10 to 50 µmol L⁻¹, demonstrating excellent analytical performance (LOD = 2.15 µmol L⁻¹) and high accuracy, with recovery rates between 99% and 108% when applied to shellfish water and pharmaceutical formulations.