Cloud point extraction for determination of cadmium in soft drinks by thermospray flame furnace atomic absorption spectrometry |
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Authors: | H len C. Rezende, Cl sia C. Nascentes,Ní via M.M. Coelho |
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Affiliation: | a Instituto de Química, Universidade Federal de Uberlândia, 38400-902, Uberlândia, MG, Brazil;b Departamento de Química, Universidade Federal de Minas Gerais, 31270-901 Belo Horizonte, MG, Brazil |
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Abstract: | Cloud point extraction (CPE) is proposed as a preconcentration procedure for the determination of Cd in soft drinks by thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS). The cadmium reacted with pyridyl-azo-naphthol (PAN) to form hydrophobic chelates, which were extracted into the micelles of Triton X-114 in a solution buffered at pH 9. NaCl was used for the phase separation. The variables which affect the preconcentration were optimized using a 23 factorial design and central composite design (CCD). A response surface maximum point was obtained, and the critical values were a concentration of 0.13 mmol L? 1 PAN, 0.03% m/v Triton X-114 and 2.3% m/v NaCl. Under the optimized conditions, after the extraction and preconcentration steps, a sample volume of 100 μL was introduced into the hot Ni tube using water as the carrier at a flow rate of 0.4 mL min? 1. The values obtained for the detection limit, relative standard deviation and preconcentration factor were 0.0178 μg L? 1, 4.1% (n = 8) and 55.5, respectively. The accuracy of the proposed method was demonstrated by performing addition-recovery experiments. Recoveries varied from 88 to 104%. |
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Keywords: | Cloud point TS-FF-AAS Cadmium Soft drink Factorial design |
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