Electrospun poly(vinylbenzyl chloride) nanofibres functionalised with tris-(2,2′-pyridylimidazole)iron(III): A test strip for detection of ascorbic acid and dopamine

A test strip for the detection of ascorbic acid as well as dopamine employing the reduction of tris-(2,2′-pyridylimidazole)iron(III) immobilised on poly(vinylbenzyl chloride) nanofibres is reported. The strip is based on the standard spectrophotometric procedure for the detection of ascorbic acid in solution using the tris-(2,2′-pyridylimidazole)iron(III) complex, generated in situ, as the indicator. Poly(vinylbenzyl chloride) nanofibres were fabricated through electrospinning followed by post functionalization with a 2-(2′-pyridyl)-imidazole ligand and complexation with iron(III) to form a yellow fibre strip. On addition of ascorbic acid, the fibre strip turned red as a result of the reduction of the complexed iron(III) to iron(II). Similarly, dopamine is believed to form a high spin Fe(II) complex that yields a blue fibre strip. The nanofibre-based approach is much better and simpler as it eliminates the sample preparation step as well as the use of instrumentation because all the required reagents are incorporated within the nanofibre platform. The eyeball detection limit of the fibre test strip was 17.6 mg L−1 for ascorbic acid and 18.4 mg L−1 for dopamine, respectively. The LOD and LOQ values of ascorbic acid were 2.1 and 6.4 mg L−1, respectively, and 1.7 and 5.1 mg L−1 for dopamine, respectively.