An environmentally relevant solid-state sensor for the trace detection of triclopyr herbicide

A novel solid-contact potentiometric sensor was developed for the selective and trace-level detection of triclopyr (Tcpy), an environmentally persistent pyridine-based herbicide. The sensor comprises a poly(vinyl chloride) (PVC) membrane incorporating tetradecylammonium bromide (TDAB) as the ion-exchanger and <i>o</i>-nitrophenyl octyl ether (<i>o</i>-NPOE) as the plasticizer, supported on a glassy carbon electrode modified with reduced graphene oxide (rGO). The introduction of rGO significantly enhanced the sensor's electron transfer kinetics, signal stability, and interfacial capacitance, enabling a near-Nernstian response of -55.7 mV per decade over a linear concentration range of 3.0 × 10^-6 to 1.0 × 10^-3 M, with a detection limit of 7.6 × 10^-7 M. The sensor exhibited a fast response time (<5 s), excellent selectivity against structurally related herbicides and common anions, and outstanding potential stability, with a drift as low as 18.3 μV s^-1. Its analytical performance was validated through the quantification of triclopyr in spiked environmental water samples and a commercial pesticide formulation (Garlon 3A), with recovery rates ranging from 96% to 102% and results statistically comparable to HPLC measurements. This work demonstrates a cost-effective, reliable, and field-deployable platform for monitoring triclopyr contamination, highlighting the promising role of rGO-based solid-contact ion-selective electrodes in environmental sensing.