An Electrochemical Sensor for Diphenylamine Detection Based on Reduced Graphene Oxide/Fe(3)O(4)-Molecularly Imprinted Polymer with 1,4-Butanediyl-3,3′-bis-l-vinylimidazolium Dihexafluorophosphate Ionic Liquid as Cross-Linker

In this paper, we report a new composite of reduced graphene oxide/Fe(3)O(4)-ionic liquid based molecularly imprinted polymer (RGO/Fe(3)O(4)-IL-MIP) fabricated for diphenylamine (DPA) detection. RGO/Fe(3)O(4)-IL-MIP was prepared with RGO/Fe(3)O(4) as supporter, ionic liquid 1-vinyl-3-butylimidazolium hexafluorophosphate ([VC(4)mim][PF(6)]) as functional monomer, ionic liquid 1,4-butanediyl-3,3’-bis-l-vinylimidazolium dihexafluorophosphate ([V(2)C(4)(mim)(2)][(PF(6))(2)]) as cross-linker, and diphenylamine (DPA) as template molecule. Fourier transform infrared spectroscopy, thermal gravimetric analysis, scanning electron microscopy, and vibrating sample magnetometer were employed to characterize the RGO/Fe(3)O(4)-IL-MIP composite. RGO/Fe(3)O(4)-IL-MIP was then drop-cast onto a glassy carbon electrode to construct an electrochemical sensor for DPA. The differential pulse voltammetry (DPV) peak current response for 20 μM DPA of RGO/Fe(3)O(4)-IL-MIP modified glassy carbon electrode (GCE) was 3.24 and 1.68 times that of RGO/Fe(3)O(4)-IL-NIP and RGO/Fe(3)O(4)-EGDMA-MIP modified GCEs, respectively, indicating the advantage of RGO/Fe(3)O(4)-IL-MIP based on ionic liquid (IL) as a cross-linker. The RGO/Fe(3)O(4)-IL-MIP sensor demonstrated good recognition for DPA. Under the optimized conditions, the RGO/Fe(3)O(4)-IL-MIP sensor exhibited a DPA detection limit of 0.05 μM (S/N = 3) with a linear range of 0.1–30 μM. Moreover, the new RGO/Fe(3)O(4)-IL-MIP based sensor detected DPA in real samples with satisfactory results.