Extraction of Heavy Metal Ions from Aqueous Solutions into In Situ Formed Ionic Liquids Followed by Determination by Microwave Plasma Atomic Emission Spectrometry

Ionic liquids based on quaternary ammonium cations—tetrahexylammonium dioctyl sulfosuccinate (THADOSS) and tetrabutylammonium dioctyl sulfosuccinate—were synthesized in situ by mixing aqueous solutions of salts yielding the cation and anion components of the ionic liquid. The ionic liquids were tested for the extraction of heavy metal ions from aqueous solutions. The Cd(II), Co(II), Cu(II), Ni(II), Pb(II), and Zn(II) ions were quantitatively extracted into the in situ formed THADOSS in the presence of 4-(2-pyridylazo)resorcinol (1 × 10^–3 M) at pH 4.9 within 1 min. The study demonstrated the feasibility of determining metals by microwave plasma atomic emission spectrometry after extraction into ionic liquids. The limits of detection ranged from 2 to 25 µg/L.