Electrochemical quantification of sulfamethoxazole antibiotic in environmental water using zeolitic imidazolate framework (ZIF)-derived single-atom cobalt catalyst in nitrogen-doped carbon nanostructures

Abstract

An electrochemical sensor based on single-atom cobalt-anchored nitrogen-doped carbon catalysts (Co/N–C SACs), synthesized by pyrolyzing zeolitic imidazolate frameworks (Co-ZIF-8), was constructed to quantify sulfamethoxazole (SMX), a member of the sulfonamide family of antibiotics, in environmental water samples. The quantification depends on the electrocatalytic oxidation of the aromatic –NH₂ group in the SMX molecule to the hydroxylamine group (–NHOH). The sensor was fabricated by depositing the Co/N–C SAC suspension (in a mixture of water, ethanol, and Nafion) on a glassy carbon (GC) electrode surface. The response of the sensor showed a linear relationship with SMX in a wide range of concentration (0.08–66.5 μM) with a limit of detection (LOD) of ∼15 nM at a signal-to-noise (S/N) ratio of 3. The sensor also had high repeatability, reproducibility, and stability. Moreover, it exhibited high selectivity and resistance to interference in the presence of other antibiotics (trimethoprim, ciprofloxacin, and norfloxacin selected randomly), endocrine disruptors (17β-estradiol), pesticides (carbaryl), common aqueous ions (Na⁺, K⁺, Fe³⁺, Cu²⁺, Ca²⁺, Cl⁻, Br⁻, CO₃²⁻, SO₄²⁻, and NO₃⁻), and common surfactants (sodium dodecyl sulfate and Triton X-100). Furthermore, the sensor was used to quantify the SMX in environmental water samples (lake water, groundwater, and secondary wastewater) with high accuracy. This electrochemical method can be used for quantifying SMX in environmental water samples for various applications, including biomedical analysis, environmental pollutant detection, and water safety evaluation.