Separation and preconcentration of ultra trace amounts of beryllium in water samples using mixed micelle-mediated extraction and determination by inductively coupled plasma-atomic emission spectrometry

In the present study a cloud point extraction process using mixed micelle of the cationic surfactant cetyl-pyridinium chloride (CPC) and non-ionic surfactant Triton X-114 for extraction of beryllium from aqueous solutions is developed. The extraction of analyte from aqueous samples was performed in the presence of 1,8-dihydroxyanthrone as chelating agent in buffer media of pH 9.5. After phase separation, the surfactant-rich phase was diluted with 0.4 mL of a 60:40 methanol-water mixture containing 0.03 mL HNO3. Then, the enriched analyte in the surfactant-rich phase was determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The different variables affecting the complexation and extraction conditions were optimized. Under the optimum conditions (i.e. 1.6 x 10(-4) mol L-1 1,8-dihydroxyanthrone, 1.2 x 10(-4) mol L-1 CPC, 0.15% (v/v) Triton X-114, 50 degrees C equilibrium temperature) the calibration graph was linear in the range of 0.006-80 ng mL(-1) with detection limit of 0.001 ng mL(-1) and the precision (R.S.D.%) for five replicate determinations at 18 ng mL(-1) of Be(II) was better than 2.9%. In this manner the preconcentration and enrichment factors were 16.7 and 24.8, respectively. Under the presence of foreign ions no significant interference was observed. Finally, the proposed method was successfully utilized for the determination of this cation in water samples. (C) 2007 Published by Elsevier B.V.