1-Butyl-3-methylimidazolium based ionic liquid as solvent for determination of hydrophobic naphthol with the electrogenerated chemiluminescence of tris(2,2′-bipyridine) ruthenium(ii)

Abstract

In this paper, we described the electrogenerated chemiluminescence (ECL) processes of tris(2,2′-bipyridine) ruthenium(II) (Ru(bpy)₃²⁺) in room-temperature ionic liquid (RTIL). The results showed that ECL signals in RTIL, 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF₄), were stronger than those obtained in aqueous solutions, which means that the RTIL could be used as a good solvent for ECL. The effect of tri-n-propylamine (TPrA) on the ECL process in [Bmim]BF₄ was also investigated and the results showed that the ECL peak occurred at 1.9 V, which is more positive than the previous reports in aqueous solutions, and the ECL intensity reached the maximum when the scan rate of CV is 200 mV s⁻¹. Moreover, the ECL signal can be quenched by oxygen due to the reaction of oxygen with TPrA˙ and Ru(bpy)₃⁺. Finally, the inhibition of Ru(bpy)₃²⁺ ECL by water-insoluble analyte, naphthol, was carried out and the results showed that the ECL signal can be quenched completely by naphthol at a very low concentration (1.0 × 10⁻⁶ M).