Surface plasmon resonance based fiber–optic nanosensor for the pesticide fenitrothion utilizing Ta₂O₅ nanostructures sequestered onto a reduced graphene oxide matrix

A surface plasmon resonance study was carried out for the identification and determination of the organophosphate pesticide fenitrothion via an optical fiber sensor. A thin layer of silver was deposited on the unclad core of silica optical fiber for plasmon generation. This was followed by the deposition of a sensing surface comprising a layer of tantalum(V) oxide nanoparticles sequestered in a nano–scaled matrix of reduced graphene oxide. The sensing mechanism is due to the interaction of fenitrothion with the silver film which leads to a change in refractive index.. Characterized by a wavelength interrogation scheme, the fiber–optic sensor exhibited a red shift equalling 56 nm corresponding to fenitrothion concentration in the range 0.25–4 μM including the blank solution. The spectral sensitivity is 24 nm μM⁻¹, the limit of detection is 38 nM, and the response time is as short as 23 s. The sensor is selective, repeatable and works at ambient temperature.