An all-solid-state potentiometric sensor for dichlorprop based on molecularly imprinted membranes and rGO-modified screen-printed electrodes

Abstract

A highly selective all-solid-state potentiometric sensor was developed for the determination of the chlorophenoxy herbicide dichlorprop (2,4-DP) by integrating a molecularly imprinted polymer (MIP) recognition element with a reduced graphene oxide (rGO) solid-contact transducer on a screen-printed carbon electrode (SPCE) platform. The MIP was synthesized via free-radical bulk polymerization using methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the crosslinker, generating selective binding sites complementary to dichlorprop. The incorporation of rGO significantly enhanced interfacial capacitance and minimized potential drift, resulting in improved signal stability and reproducibility. Under optimized conditions, the sensor exhibited a near-Nernstian response with a slope of −56 mV per decade over a linear concentration range of 7.0 × 10⁻⁶ to 1.0 × 10⁻³ M, and a detection limit in the order of 3.0 × 10⁻⁶ M. The proposed sensor demonstrated excellent selectivity toward dichlorprop over structurally related phenoxy herbicides (2,4-D, MCPA, and mecoprop) and common inorganic anions, attributed to the high specificity of the imprinted binding sites. Chronopotentiometric measurements confirmed a significant reduction in potential drift and a substantial increase in interfacial capacitance for the rGO-modified electrode compared to the unmodified counterpart. The sensor exhibited rapid response (≤10 s), high repeatability (RSD < 3%), and good operational stability. Its practical applicability was validated through the analysis of spiked environmental water samples and commercial herbicide formulations, yielding recoveries in the range of 95–105%, in excellent agreement with high-performance liquid chromatography (HPLC) results. This work presents a robust, miniaturized, and cost-effective sensing platform for rapid on-site monitoring of dichlorprop, highlighting the synergistic integration of molecular imprinting and nanostructured solid-contact transducers for advanced environmental analysis.