Ultra-sensitive electrochemical determination of malathion based on phytic acid-polyaniline doped bimetallic zeolitic imidazolate frameworks

The widespread use of malathion (MA) poses significant risks to environmental safety and human health, necessitating the development of highly sensitive detection platforms. Herein, a novel composite was first synthesized by integrating phytic acid (PA) doped polyaniline (PANI) with a bimetallic Cu and Zn zeolitic imidazolate framework (CZ-ZIF), denoted as PCZ-ZIF. Subsequently, the PCZ-ZIF composite was immobilized onto a fluorine-doped tin oxide (FTO) electrode to construct an ultra-sensitive electrochemical sensor (designated as PCZ-ZIF/FTO) for the precise detection of MA. PA bridges PANI and CZ-ZIF via hydrogen bonding and P–O–M coordination. The incorporation of Cu 2+ into the ZIF framework provides a strong affinity toward the P S bond in MA, while the doping of PANI significantly accelerates the interfacial electron transfer. Consequently, the PCZ-ZIF/FTO sensor exhibits exceptional electrocatalytic activity through a specific two-electron reduction process. Under optimal conditions, the sensor achieves a broad linear detection range from 1 ppt to 10 ppb and an ultra-low limit of detection (LOD) of 0.210 ppt. Furthermore, the device demonstrates outstanding reproducibility, excellent storage stability, and robust anti-interference capabilities against non-target species. Practical applicability was successfully validated in surface water and groundwater samples, yielding recoveries in agreement with standard high-performance liquid chromatography (HPLC) methods. Our work presents a highly reliable and promising strategy for the trace-level monitoring of organophosphorus pesticides in real environments.