Response of a new multi-walled carbon nanotubes modified carbon paste electrode to 1-hexyl-3-methylimidazolium cation in aqueous solution

1-Hexyl-3-methylimidazolium tetraphenylborate ([C 6 mim]-TPB) was synthesized and explored as ion exchanger in carbon paste electrode (CPE) as an ion-selective electrode (ISE). The electrode was found to be optimal with the composition of 42 % graphite powder, 20 % paraffin oil, 30 % ion exchanger, 5 % MWCNTs, and 3 % nano-silica. The as-prepared electrode exhibits a Nernstian response (59.2 mV per decade) to 1-hexyl-3-methylimidazolium cation in the concentration range from 1.0 × 10 −5 to 1.0 × 10 −2  mol kg −1 . The novel as-prepared MWCNTs/nano-silica/CPE was successfully applied in the detection of [C 6 mim] + in distilled water, tap water, and river water with satisfactory results.