Preconcentration Procedure Using Cloud Point Extraction In The Presence Of Electrolyte For Cadmium Determination By Flame Atomic Absorption Spectrometry

This paper describes a micelle-mediated phase separation in the presence of electrolyte as a preconcentration method for cadmium determination by flame atomic absorption spectrometry (FAAS). Cadmium was complexed with ammonium O,O-diethyldithiophosphate (DDTP) in an acidic medium (0.32 mol l- 1 HCl) using Triton X-114 as surfactant and quantitatively extracted into a small volume (about 20 μl) of the surfactant-rich phase after centrifugation. The chemical variables that affect the cloud point extraction, such as complexing time (0-20 min), Triton X114 concentration (0.043-0.87% w/v) and complexing agent concentration (0.01-0.1 mol l- 1), were investigated. The cloud point is formed in the presence of NaCl at room temperature (25 °C), and the electrolyte concentration (0.5-5% w/v) was also investigated. Under optimized conditions, only 8 ml of sample was used in the presence of 0.043% w/v Triton X-114 and 1% (w/v) NaCl. This method permitted limits of detection and quantification of 0.9 μg l- 1 and 2.9 μg l- 1 Cd, respectively, and a linear calibration range from 3 to 400 μg l- 1 Cd. The proposed method was applied to Cd determination in physiological solutions (containing 0.9% (w/v) of NaCl), mineral water, lake water and cigarette samples (tobacco). © 2005 Elsevier B.V. All rights reserved.605743748Carabias-Martínez, R., Rodríguez-Gonzalo, E., Moreno-Cordero, B., Pérez-Pavón, J.L., Garcia-Pinto, C., Laespada, E.F., Surfactant cloud point extraction and preconcentration of organic compounds prior to chromatography and capillary electrophoresis (2000) J. Chromatogr. a, 902, pp. 251-265Alfassi, Z.B., Wai, C.M., (2000) Preconcentration Techniques for Trace Elements, , CRC Press Boca RatonCave, M.R., Butler, O., Cook, J.M., Cresser, M.S., Garden, L.M., Holden, A.J., Miles, D.L., Environmental analysis-atomic spectrometry update (1999) J. Anal. At. Spectrom., 14, pp. 279-352Stalikas, C.D., Micelle-mediated extraction as a tool for separation and preconcentration in metal analysis (2002) Trends Anal. Chem., 21, pp. 343-355Manzoori, J.L., Bavili-Tabrizi, A., The application of cloud point preconcentration for the determination of Cu in real samples by flame atomic absorption spectrometry (2002) Microchem. J., 72, pp. 1-7McIntire, G.L., Micelles in analytical chemistry (1990) Crit. Rev. Anal. Chem., 21, pp. 257-278Cline Love, L.J., Habarta, J.G., Dorsey, J.G., The micelle-analytical chemistry interface (1984) Anal. Chem., 56, pp. 1132A-1148AKumar, S., Sharma, D., Din, K., Effect of additives on the clouding behaviour of sodium dodecyl sulfate plus tetra-n-butylammonium bromide system (2004) J. Surfactants Deterg., 7, pp. 271-275Nascentes, C.C., Arruda, M.A.Z., Cloud point formation based on mixed micelles in the presence of electroytes for cobalt extraction and preconcentration (2003) Talanta, 61, pp. 759-768(1995) The THGA Graphite Furnace: Techniques and Recommended Conditions, Technical Documentation, Release 1.2, , Bodenseewerk Perkin-Elmer GmbH, Überlingen, GermanyBorges, D.L.G., Veiga, M.A.M.S., Frescura, V.L.A., Welz, B., Curtius, A.J., Cloud-point extraction for the determination of Cd, Pb and Pd in blood by electrothermal atomic absorption spectrometry, using Ir or Ru as permanent modifiers (2003) J. Anal. At. Spectrom., 18, pp. 501-507Silva, M.A.M., Frescura, V.L.A., Aguilera, F.J.N., Curtius, A.J., Determination of Ag and Au in geological samples by flame atomic absorption spectrometry after cloud point extraction (1998) J. Anal. At. Spectrom., 13, pp. 1369-1373Bode, H., Arnswald, W., Substituted dithiophosphates: II. Formation of metal diethyldithiophophates and extraction from mineral acid solutions (1962) Fresenius Z. Anal. Chem., 185, pp. 179-201Silva, M.A.M., Frescura, V.L.A., Curtius, A.J., Determination of trace elements in water samples by ultrasonic nebulization inductively coupled plasma mass spectrometry after cloud point extraction (2000) Spectrochim. Acta, Part B: Atom. Spectrosc., 55, pp. 803-813Chen, J., Teo, K.C., Determination of cadmium, copper, lead and zinc in water samples by flame atomic absorption spectrometry after cloud point extraction (2001) Anal. Chim. Acta, 450, pp. 215-222Pinto, C.G., Pavón, J.L.P., Cordero, B.M., Cloud point preconcentration and flame atomic absorption spectrometry: Application to the determination of cadmium (1996) J. Anal. At. Spectrom., 11, pp. 37-41Tani, H., Kamidate, T., Watanabe, T., Micelle-mediated extraction (1997) J. Chromatogr. a, 780, pp. 229-241Gu, T., Galera-Gómez, P.A., Clouding of Triton X-114: The effect of added electrolytes on the cloud point of Triton X-114 in the presence of ionic surfactants (1995) Colloids Surf., a Physicochem. Eng. Asp., 104, pp. 307-312Komaromy-Hiller, G., Calkins, N., Wandruszka, R., Changes in polarity and aggregation number upon clouding of a nonionic detergent: Effect of ionic surfactants and sodium chloride (1996) Langmuir, 12, pp. 916-920Armstrong, J.K., Chowdhry, B.Z., Snowden, M.J., Leharne, S.A., Effect of sodium chloride upon micellization and phase separation transitions in aqueous solutions of triblock copolymers: A high-sensitivity differential scanning calorimetry study (1998) Langmuir, 14, pp. 2004-2010Methods Committee, A., Recomendations for the definition, estimation and use of detection limit (1987) Analyst, 112, pp. 199-204Manzoori, J.L., Bavili-Tabrizi, A., Cloud point preconcentration and flame atomic absorption spectrometric determination of Cd and Pb in human hair (2002) Anal. Chim. Acta, 470, pp. 215-221Tarley, C.R.T., Arruda, M.A.Z., A sensitive method for cadmium determination using an on-line polyurethane foam preconcentration system and thermospray flame furnace atomic absorption spectrometry (2004) Anal. Sci., 20, pp. 961-96