Indicator-catalyst displacement assay for tandem detection and signal amplification of dimethoate organophosphate pesticide

Cheuk Fai Stephen CHOW, Qian TANG, Cheng-Bin GONG, Wai Yin Steve MUNG

Research output: Contribution to journalArticlespeer-review

Abstract

This paper describes the chemosensing and catalytic amplification properties of [MnIII(TPP)(NCS)]–[PdII(DMSO)Cl2] (1, TPP = 5,10,15,20-tetraphenyl-21H,23H-porphine) for detecting the organophosphate pesticide dimethoate. Complex 1 selectively detects dimethoate, resulting in a visual color change from yellowish-brown to green with a UV–vis spectroscopic method detection limit (MDL) of 22.7 μM. This selectivity is attributed to the formation of a more stable PdII(dimethoate)2Cl2 adduct, resulting in the release of the colored MnIII(TPP)(NCS) unit from complex 1. Interestingly, the free PdII(dimethoate)2Cl2 released acts as a catalyst for the Heck coupling reaction of 5-diethylamino-2-iodo-phenyl ester (2), producing the highly fluorescent 7-diethylaminocoumarin (3). This catalytic process results in significant signal amplification, enhancing the original sensitivity by 25 times, with a spectrofluorimetric MDL of 0.9 μM. The proposed indicator-catalyst displacement assay successfully quantifies dimethoate concentrations in natural water samples, exhibiting good recoveries (92.5–108.1%) and low relative standard deviations (1.2–6.2%). Copyright © 2024 Elsevier B.V. All rights reserved.

Original languageEnglish
Article number135335
JournalSensors and Actuators B: Chemical
Volume405
Early online dateJan 2024
DOIs
Publication statusE-pub ahead of print - Jan 2024

Citation

Chow, C.-F., Tang, Q., Gong, C.-B., & Mung, S. W.-Y. (2024). Indicator-catalyst displacement assay for tandem detection and signal amplification of dimethoate organophosphate pesticide. Sensors and Actuators B: Chemical, 405, Article 135335. https://doi.org/10.1016/j.snb.2024.135335

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