Selective Detection of Chloramphenicol Using Electroactive Azo-Bridged Porous Organic Polymers

The sensitive detection of chloramphenicol (CAP), a widely regulated antibiotic associated with severe toxicity and antimicrobial resistance, is crucial for food safety and environmental monitoring. Herein, we report electroactive nanoporous azo-linked porous organic polymers (POP), azo-POP-1–3 as electrochemical sensors for selective detection of CAP. They possess a nanometer pore size (1.4–1.5 nm) and a surface area of 139.1 m2 g–1. Due to the low charge-transfer resistance (Rct = 113.51 Ω cm2), the azo-POP-1-modified glassy carbon (GC) electrode exhibited superior electrochemical response to CAP at −0.845 V compared to bare GC and other POPs. Differential pulse voltammetry (DPV) revealed a limit of detection (LoD) of 0.310 μM in the 0.5–5 μM concentration range. Similarly, the sensitivity in the low-concentration region was calculated to be 2.405 μA μM–1 cm–2. Kinetic studies revealed an adsorption-controlled, quasi-reversible four-electron transfer reduction process (Γ = 2.65 × 10–8 mol cm–2) at the azo-POP-1@GC. Notably, the sensor showed excellent reproducibility (RSD = 3.34%), repeatability (RSD = 1.45%), and long-term stability with ∼92% signal retention over 15 days. Also, azo-POP-1@GC was highly selective to CAP in the presence of interfering species. Further, the applicability of azo-POP-1@GC sensor was demonstrated by CAP detection in milk, honey, and eye-drop samples, with recoveries of 98–103%.