Paper-based electrochemical sensors with reduced graphene nanoribbons for simultaneous detection of sulfamethoxazole and trimethoprim in water samples

Failure to control the levels of emerging pollutants in water supply can affect the quality of human life, and this may be mitigated with a low-cost, real-time monitoring system. Herein, we describe a paper-based fully printed electrochemical sensor with reduced graphene nanoribbons (rGNR) capable of detecting sulfamethoxazole (SMX) and trimethoprim (TMP) antibiotics simultaneously in real water samples. The electrodes were printed on parchment paper, which is environmentally friendly and has an efficient printing capacity. Deposition of rGNRs in the matrix was confirmed with Raman spectroscopy, transmission electron microscopy (TEM), and X-ray photoemission spectroscopy (XPS). Optimized sensing performance was obtained using an electrochemical treatment of the electrodes at neutral pH. The paper-based sensor displayed a linear response from 1 μmol l−1 to 10 μmol l−1 for both antibiotics, with detection limits of 0.09 μmol l−1 and 0.04 μmol l−1 for SMX and TMP, respectively. The sensor was reproducible, with an RSD below 5%, and selective for the antibiotics including in real samples, in a demonstration of its potential for real-time monitoring of water supply systems.