Determination of some metal ions with AAS by enrichment with cloud point extraction and optimization of analysis conditions with experimental design

In this study, a cloud point extraction method for preconcentration of Cu2+, Cd2+, Pb2+, Co2+ and Ni2+ ions has been developed prior to their atomic absorption spectrometric determinations. Tergitol 15-s-7 and Tergitol 15-s-9 which are nonionic surfactants are used as miceller media. Taguchi Method was applied to optimize cloud point extraction (CPE) conditions for Cu2+, Cd2+, Pb2+, Co2+ and Ni2+ ions determination in environmental samples. Six relevant factors, i.e. surfactant concentration, ligand concentration, pH, ionic strength, equilibrium time and sample volume were selected and the effects of each factor were studied at five levels on the extraction efficiency of Cu2+, Cd2+, Pb2+, Co2+ and Ni2+ ions and optimized. The effects of some alkaline, alkaline earth and some metal ions on the recoveries of analytes were also examined. The recoveries of metal ions by using Tergitol 15-s-7 and Tergitol 15-s-9 under the optimum experimental conditions were ranged from 83.0 to 110.0% and 71.0 to 100.0%, respectively. In order to validate the accuracy of the method for determination of metal ions, certified reference material (sewage sludge-BCR 146-R) was used. It was understood that the determined values are in good agreement with the certified values. Proposed seperation and preconcentration method was applied to river water samples. The method was permitted to obtain a detection limit of Cu2+,Cd2+, Pb2+, Co2+ and Ni2+ for Tergitol 15-s-7 and Tergitol 15-s-9 were 9.76, 8.95, 22.50, 18.20, 6.90 ng mL-1 and 14.20, 15.80, 37.50, 21.20, 6.62 ng mL-1, respectively.