Cloud point extraction and simultaneous determination of zirconium and hafnium using ICP-OES

Abstract

In the present study a simple versatile separation method using cloud point procedure for extraction of trace levels of zirconium and hafnium is proposed. The extraction of analytes from aqueous samples was performed in the presence of quinalizarine as chelating agent and Triton X-114 as a non-ionic surfactant. After phase separation, the surfactant-rich phase was diluted with 30% (v/v) propanol solution containing 1 mol l−1 HNO3. Then, the enriched analytes in the surfactant-rich phase were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The different variables affecting the complexation and extraction conditions were optimized. Under the optimum conditions (i.e. 3.4×10−5 moll−1 quinalizarine, 0.1% (w/v) Triton X-114, 55 °C equilibrium temperature) the calibration graphs were linear in the range of 0.5–1000 μg l−1 with detection limits (DLs) of 0.26 and 0.31 μg l−1 for Zr and Hf, respectively. Under the presence of foreign ions no significant interference was observed. The precision (%RSD) for 8 replicate determinations at 200 μg l−1 of Zr and Hf was better than 2.9% and the enrichment factors were obtained as 38.9 and 35.8 for Zr and Hf, respectively. Finally, the proposed method was successfully utilized for the determination of these cations in water and alloy samples.