Voltammetric sensor for determination of kojic acid in real samples using carbon paste electrode modified by [Fe(HL)2Cl2] nano-complex and ionic liquid

A new mononuclear Fe(II) complex with the formula [Fe(HL)2Cl2] (1) (HL= N-(2-hydroxy-1-naphthylidene)-2-methyl aniline) was synthesized and characterized by Fourier transform infrared spectroscopy (FT-IR), UV–Vis and elemental analysis. The spectroscopy analyses revealed the two Schiff base ligands via oxygen and nitrogen atoms and two chloride atoms create an octahedral geometry. The nano-size of [Fe(HL)2Cl2] complex (2) was synthesized by the sonochemical process. Characterization of nano-complex (2) was carried out via X-ray powder diffraction (XRD), scanning electron microscopy (SEM), UV-Vis, FT-IR spectroscopy. The nano-complex (2) average size synthesized via the sonochemical method was approximately 52 nm. In this work, a simple sensor based on a carbon paste electrode modified with [Fe(HL)2Cl2] nano-complex and the ionic liquid - IL (1-Butyl-3-methylimidazolium hexafluorophosphate) was developed ([Fe(HL)2Cl2] nano-complex-IL/CPE) for convenient and fast electrochemical detection of kojic acid. The modified electrode considerably improves voltammetric sensitivity toward kojic acid compared to the bare electrode. Experimental conditions influencing the analytical performance of the modified electrode were optimized. Under optimal conditions, the oxidation peak current was proportional to kojic acid concentration in the range from 0.3 to 237.0 μM with a detection limit of 0.09±0.001 μM. The [Fe(HL)2Cl2] nano-complex-IL/CPE sensor was successfully applied for the highly sensitive determination of kojic acid in real samples with satisfactory results.