Ionic Liquid-based Aqueous Two-phase System Coupled With Flame Atomic Absorption Spectrometry for the Preconcentration and Determination of Copper in Water Samples

An ionic liquid/aqueous two-phase system (IL/ATPS) prior to flame atomic absorption spectrometry analysis was developed for the selective extraction of copper at trace levels in aqueous solution. The IL/ATPS was formed with ionic liquid consisting of three different cationic groups (phosphonium, ammonium, and imidazolium) having bromide as the anion group, Triton (R) X-100, and K2HPO4 in the presence of 8-hydroxyquinoline (8-HQ). The amount of ionic liquid, type and amount of salt, amount of 8-HQ, complexation of pH, and amount of Triton X-100 were optimized to achieve high extraction efficiency. Linearity for copper was in the range of 20-500 mu g L-1. The volume of the ionic liquid-rich upper phase varied from 250 to 700 mu L. The limit of detection was 11, 12, and 17 mu g L-1 for MOIM-Br, TOA-Br, and TOP-Br, respectively. The developed method was successfully applied to tap water, well water, and seawater samples.