An imidazole derivative, 2-(2'-pyridyl) imidazole (PIMH), was developed as a colorimetric probe for the qualitative analysis of Fe2+ in aqueous solution. PIMH was then used to post-functionalize poly(vinylbenzyl chloride) (PVBC) nanofibers after electrospinning so as to afford a solid state colorimetric probe. Upon treatment with Fe2+ the probe displayed a distinctive color change both in liquid and solid platforms. The linear dynamic range for the colorimetric determination of Fe2+ was 0.0988-3.5 mu g mL(-1). The ligand showed a high chromogenic selectivity for Fe2+ over other cations with a detection limit of 0.102 mu g mL(-1) in solution (lower than the WHO drinking water guideline limit of 2 mg L-1), and 2 mu g mL(-1) in the solid state. The concentration of Fe2+ in a certified reference material (Iron, Ferrous, 1072) was found to be 2.39 +/- 0.01 mg L-1, which was comparable with the certified value of 2.44 +/- 0.12 mg L-1. Application of the probe to real samples spiked with Fe2+ achieved recoveries of over 97% confirming accuracy of the method and its potential for on-site monitoring. (C) 2013 Elsevier B.V. All rights reserved.