Room-temperature ionic liquids as electrolytes in electroanalytical determination of traces of 2-furaldehyde from oil and related wastewaters from refining processes

Three different ionic liquids, 1-ethyl-3-methylimidazolium tetrafluoroborate, [EMIM][BF4]; 1-butyl-3-methylimidazolium trifluoromethanesulfonate, [BMIM][OTf]; and 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide [bmpyrr][NTf2] were studied as electrolytes in the electroanalytical quantification of 2-furaldehyde using square wave and differential pulse voltammetries. On applying a cathodic scan, a well-defined 2-electron wave was observed corresponding to the reduction of 2-furaldehyde to furfuryl alcohol. The electrochemical stability of the ionic liquids as electrolytes for analytical aspects and electrokinetic studies was investigated using a glassy carbon electrode (GCE). The measurements were carried out in a designed double-wall three-electrode cell, using two platinum wires as the quasi-reference and counter electrodes. Differential pulse voltammetry was found to be the most sensitive method at GCE. The detection limits of 1.4, 19.0 and 2.5 μg g−1 were obtained for the determination of 2-furaldehyde in [EMIM][BF4], [BMIM][OTf] and [BMPyrr][NTf2], respectively. At a concentration of 50 μg g−1, the maximum relative standard deviation (n = 3) was 4.9%. The effect of water content of the ionic liquids on their potential windows and waveforms was also investigated. The proposed method was successfully applied to the determination of 2-furaldehyde in real samples, especially in oil matrices.