Ionic liquid-porphyrin concentrator for effective detection of Cu²⁺ ions

A facile method to determine the concentration of Cu²⁺ ions in aqueous solution was developed by using ionic liquids (ILs) as a concentrating reagent. Four hydrophobic ILs with the bis(tri uoromethanesulfonyl)imide counter anion were tested for their abilities to measure Cu²⁺ ion concentration. Results showed that 1-allyl-3-butylimidazolium bis(tri uoromethanesulfonyl)imide (ABIM) was good at concentrating Cu²⁺ ions in the form of [(TMPyP)Cu]⁴⁺, and thus the ABIM ILs only extracted [(TMPyP)Cu]⁴⁺ species from aqueous solution, whereas others showed no selectivity. In UV-vis absorption spectra, the Soret band absorbance of [(TMPyP)Cu]⁴⁺ in ABIM ILs was 17 times higher than that in water. Moreover, the band intensity increased linearly with increasing Cu²⁺ ion concentration. These results indicated that ABIM IL-TMPyPH₂ (TMPyPH₂:meso-tetrakis(N-methyl-pyridinium-4-yl)porphyrin) was an e ective concentrator for Cu²⁺ ions.Interference studies showed that other metals (Cd²⁺, Zn²⁺, Fe³⁺, Mn²⁺ determination of Cu²⁺ ion concentration using this method.