Quenching-based electrochemiluminescence detection of chlorpyrifos using a portable sensor platform

Background/aim: Chlorpyrifos (CPF) is an organophosphate pesticide extensively used in agriculture, posing significant threats to human health due to its neurotoxic effects. Its presence in food products has raised considerable public health concerns, necessitating the development of rapid, sensitive, and reliable detection methods. This study aims to design and validate an electrochemiluminescence (ECL) sensor platform operating via a quenching-based mechanism to enable ultrasensitive detection of CPF in food matrices. Materials and methods: The sensing strategy exploits the coreactant mechanism between 2-(dibutylamino)ethanol (DBAE) and [Ru(bpy)₃]²+ (tris(2,2′-bipyridyl)ruthenium(II)), wherein CPF suppresses the ECL emission by interfering with the excited-state electron transfer pathway. The sensing interface was fabricated by integrating carboxyl-functionalized multiwalled carbon nanotubes (MWCNTs) with [Ru(bpy)₃]²+ complexes, which were immobilized on a screen-printed carbon electrode using a Nafion polymer film to enhance stability and conductivity. Analytical parameters, including the limit of detection (LoD), linear range, and reproducibility, were systematically optimized. Real sample applicability was assessed using honey matrices to simulate complex food environments. Results: The developed sensor achieved a LoD of 0.24 ± 0.05 pM (2.4 × 10-¹³ M) and a linear dynamic range between 0.73 ± 0.13 pM and 100 ± 1.49 pM. In honey samples, recovery rates ranged from 96.26 ± 3.78% to 101.45 ± 4.16%, demonstrating excellent accuracy and minimal interference. The sensor showed good repeatability, with the ECL signal remaining above 80% of its initial value over eight consecutive measurements. Additionally, the relative standard deviation increased slightly from 1.81% to 2.90% over 30 days, indicating high stability of the sensor during the storage period. Conclusion: This ECL sensor provides an efficient analytical tool for detecting CPF residues in food products. The combination of MWCNT-based signal amplification and the DBAE/[Ru(bpy)₃]²+ quenching-based mechanism enables ultrasensitive performance, rendering the system promising for real-time food safety monitoring and regulatory compliance testing.