An innovative electrochemical sensor combining a carbon paper (CP) transducer with an iron-trimesic acid metal-organic framework (Fe-BTC) was developed for the detection of gemfibrozil (GEM) in environmental samples. GEM is a pharmaceutical compound used in the management and treatment of dyslipidaemias, that was recently designed by the European Union as a candidate substance for inclusion in the 5th Watch List for monitoring in surface waters due its potential toxicity to aquatic organisms. The Fe-BTC was synthesized and electrodeposited onto the CP through a simple, fast and environmentally friendly approach, and the resulting CP/Fe-BTC sensor was characterized morphologically and structurally by electrochemical, spectroscopic, microscopic, and diffraction techniques. A well-defined and irreversible oxidation peak was observed at +1.2 V. Optimal performance was obtained at pH 7 under square-wave voltammetry (10 Hz frequency, 100 mV amplitude, 10 mV step potential). The sensor exhibited two linear ranges 0.0500 to 0.400 μM and 0.400 to 4.00 μM, with sensitivity of 0.164 ± 0.008 and 0.227 ± 0.011 mA μM−1 cm−2 respectively, and a low limit of detection of 0.04 μM. Good repeatability, reproducibility and selectivity were achieved, together with excellent recoveries (94.6–104.9%) in river water and fish, validating the sensor for the analysis of these matrices. Greenness assessment using GAPI and AGREE metrics confirmed that the sensor is more environmentally sustainable than reference chromatographic methods. These results point up the potential of the CP/Fe-BTC sensor as a practical alternative for the determination of this contaminant of emerging concern in environmental samples.
