Optimization of the Nonaqueous Capillary Electrophoresis Separation of Metal Ions Using Mixture Design and Response Surface Methods

Mixture experimental design was used to enhance the separation selectivity of metal ions in nonaqueous capillary electrophoresis. The separation of cations (Ag, Fe, Cr, Mn, Cd, Co, Pb, Ni, Zn and Cu) was achieved using imidazole as UV co-ion for indirect detection. Acetic acid was chosen as an electrolyte because its cathodic electroosmotic flow permits faster separation. The composition of organic solvents is important to achieve the best separation of all metal ions. Simplex lattice design and response surface methods have proved to be an effective tool to optimize the composition of organic solvents in nonaqueous capillary electrophoresis. Full and reduced experimental design models were compared to obtain the optimum composition of solvents. Contour plots were presented to visualize the effect of the selected solvents on electrophoretic mobility. The highest electrophoretic mobilities were obtained with higher percentages of acetonitrile for all metal ions. Root mean square error (RMSE) and F-test were used to evaluate the models.

Optimization of the Nonaqueous Capillary Electrophoresis Separation of Metal Ions Using Mixture Design and Response Surface Methods

Mixture experimental design was used to enhance the separation selectivity of metal ions in nonaqueous capillary electrophoresis. The separation of cations (Ag, Fe, Cr, Mn, Cd, Co, Pb, Ni, Zn and Cu) was achieved using imidazole as UV co-ion for indirect detection. Acetic acid was chosen as an electrolyte because its cathodic electroosmotic flow permits faster separation. The composition of organic solvents is important to achieve the best separation of all metal ions. Simplex lattice design and response surface methods have proved to be an effective tool to optimize the composition of organic solvents in nonaqueous capillary electrophoresis. Full and reduced experimental design models were compared to obtain the optimum composition of solvents. Contour plots were presented to visualize the effect of the selected solvents on electrophoretic mobility. The highest electrophoretic mobilities were obtained with higher percentages of acetonitrile for all metal ions. Root mean square error (RMSE) and F-test were used to evaluate the models.

___

  • L.W. Vicki and M.G. Khaledi, J. Chromatogr. A, 859, 203 (1999).
  • K.D. Altria and M.Wallberg, J. Chromatogr. B, 714, 99 (1998).
  • H. Salimi-Mosavi and R.M. Cassidy, Anaytical Chemistry 68, 293 (1996).
  • F. Qu, L.M.Lin and Z. Chen, J. Chromatogr. A, 1022, 217 (2004).
  • M.L.Riekkola, M. Jussila, S.P.Porras and I.E. Valko, J. Chromatogr. A, 892, 155 (2000).
  • S.P. Porras and M.L. Riekkola, J. Chromatogr. A, 924, 31 (2001).
  • J.L. Glajch and J.J. Kirkland, J. Chromatogr. A, 485, 51 (1989).
  • P.M.J. Coenegracht, N. Van Tuyen, H.J. Metting and P.J.M. Coenegracht-Lamers, J. Chromatogr. A, 389, (1987).
  • A. Apichartsrangkoon and D.A. Ledward, Food Chem. 77, 317 (2002).
  • P.J. Brandvik and P.S. Daling, Chemometr. Intell. Lab. Syst. 42, 63 (1998).
  • A. Gupta, J. Appl. Stat. 28, 199 (2001).
  • T.C. Wen and W.C. Chen, J. Appl. Pol. Sci. 77, 680 (2000).
  • A.C.B.Ribeiro and I.R. De Almeida, Mater and Struct. 33, 398 (2000).
  • G. Piepel and T. Redgate, J. Am. Ceram. Society 80, 3038 (1997).
  • J.V. Nardi, W. Acchar and D. Hotza, J. Eur. Ceram. Soc. 24, 375 (2004).
  • Y. Y¨ucel and C. Demir, Talanta 63, 451 (2004).
  • T. Naes, F. Bjerke and E.M. Faergestad, Food Qual. Prefer 10, 209 (1999).
  • A. Kamoun M. Chaabouni, M. Sergent and R. Phan-Tan-Luu, Chemometr. Intell. Lab. Syst. 61, 69 (2002).
  • G. Dingstad, B. Egelandsdal and T. Naes, Chemometr. Intell. Lab. Syst. 66, 175 (2003).
  • V.C. Morris, C. Hargreaves, K. Overall, P.J. Marriott and J.G. Hughes, J. Chromatogr. A, 766, 245 (1997).