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Solute Focusing Techniques for Bioseparations

Abstract

The growth of industrial biotechnology has had a major impact on the research and development of both analytical and preparative focusing techniques. Pioneering methods such as isoelectric focusing are being modified to overcome the limitations of batch mode Operation, scale up difficulties, high power requirement, and excessive heat generation. Present advances in focusing techniques have been made by either overcoming the limitations of standard techniques or by investigating new focusing systems. Here we review the background and history of isoelectric focusing and discuss several new focusing techniques including recycle isoelectric focusing (RIEF), counteracting chromatographic electrophoresis (CACE), and countercurrent gradient chromatography (CGC).

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References

  1. Dechow, F.J. 1989. Separation and Purification Technology in Biotechnology. Noyes Publications, Park Ridge, New Jersey.

  2. Lightfoot, E.N. and Cockrem, M.C.M. 1987. What are dilute solutions. Separation Science and Technology 22: 165–189.

    CAS  Google Scholar 

  3. Heftman, E. 1975. Chromatography, a Laboratory of Chromatographic and Electrophoretic Methods. Van Nostrand Reinhold Co., New York.

    Google Scholar 

  4. Righetti, P.G. 1983. Isoelectric Focusing: Theory, Methodology, and Applications. Elsevier Biomedical Press, Amsterdam.

  5. Schumacher, E. 1957. Uber Fokussierenden lonenaustausch IV. Zur Theorie des Fokussierungseffektes. Helvetica Chimica Ada, No. 240: 2322–2340.

    Google Scholar 

  6. Kauman, W.G. 1957. Classe des Sciences de L'Academie Royale de Belgique 43: 854–868.

  7. Svensson, H. 1961. Isoelectric fractionation, analysis, and characterization of ampholytes in natural pH gradients. I. The differential equation of solute concentration at steady state and its solution for simple cases. Acta Chemica Scandinavica 15: 325–341.

    CAS  Google Scholar 

  8. Vesterburg, O. and Svensson, H. 1996. Isoelectric fractionation, analysis, and characterization of ampholytes in natural pH gradients IV. Further studies on the resolving power in connection with separation of myoglobins. Acta Chemica Scandinavica 20: 820–834.

    Google Scholar 

  9. Caspers, M.L. and Chrambach, A. 1977. Natural pH gradients formed by amino acids: Ampholyte distribution, time course, use in electrofocusing of protein, relation to pH gradients in isotachophoresis, and separator effects. Anal. Biochem. 81: 28–39.

    CAS  Google Scholar 

  10. Vesterburg, O. 1969 Synthesis and isoelectric fractionation of carrier ampholytes. Acta Chemica Scandinavica. 23: 2653–2666.

    Google Scholar 

  11. Bier, M., Ostream, J. and Marquez, R.B. 1933 A new buffering system and its use in electrophoresis and isoelectric focusing. Electrophoresis 14(10): 1011–1018.

    Google Scholar 

  12. Hausfeld, A.D. 1993. Isoelectric focusing: pH gradients established with simple buffers and a cation-selective membrane. Analytical Biochemistry 212: 237–246.

    CAS  PubMed  Google Scholar 

  13. Carrier ampholytes are available from a number of suppliers including BIO-RAD Laboratories (Richmond, CA) and Pharmacia Biotech Inc. (Piscataway, NI).

  14. Isoelectric focusing units are available from a number of suppliers including BIO-RAD Laboratories (Richmond, CA) and RAININ (Woburn, MA).

  15. Bjellqvist B., Ek K. Righetti, P.G., Gianazza E. Gorg A., Westermeir, R. and Postel, W.J. 1982. Biophy. Methods. Isoelectric focusing in immobilized pH gradients: Principle, methodology, and some appilications. J. Biochem. 6: 317–339.

    CAS  Google Scholar 

  16. Righetti, P.G., Barzachi, B., Luzanna, M., Manfredi, G. and Faupel, M. 1987. A horizontal apparatus for isoelectric protein purification in a segmented immobilized pH gradient. Biochemical and Biophysical Methods 15: 189–198.

    CAS  Google Scholar 

  17. Altland, K. and Altland, A. 1990. Pouring wide renge immobilized pH gradients with a window of extremely flattened slope. Electrophoresis 11: 337–342.

    CAS  PubMed  Google Scholar 

  18. Mosher, R.A., Thormann, W. and Bier, M. 1988. Experimental and theoretical dynamics of isoelectric focusing, II. Elucidation of the impact of the electrode assembly. J. of Chromatogr. 436: 191–204.

    CAS  Google Scholar 

  19. Coronel, E.C., Little, B.W. and Alhadeff, J. A. 1993. Immobilized pH gradient focusing of alkaline proteins: Analysis of the isoform composition of purified human non-secretory ribonucleases from kidney, liver and spleen. Biochemical Journal 296: 553–556.

    CAS  PubMed  PubMed Central  Google Scholar 

  20. Righetti, P.G. and Chiari, M. 1993. Conventional isoelectric focusing and immobilized pH gradients: An overview. Chromatogr. Science Series (Capillary Electrophoresis Technology) 64: 89–116.

    CAS  Google Scholar 

  21. Sinha, P., Galacteros, F., Righetti, P.G., Kohlmeier, M. and Koettgen, E. 1993. Analysis of hemoglobin variants using immobilized pH gradients. Eur. J. Clin. Chem. Clin. Biochem. 31: 91–96.

    CAS  PubMed  Google Scholar 

  22. Altland, K. 1990. IPGMAKER: A program for IBM-compatible personal computers to create and test recipes for immobilized pH gradients. Electrophoresis 11: 140–147.

    CAS  PubMed  Google Scholar 

  23. Tonani, C. and Righetti, P.G. G 1991. Immobilized pH gradients (IPG) simulator—an additional step in pH gradient engineering: I. Linear pH gradients. Electrophoresis 12: 1011–1021.

    CAS  PubMed  Google Scholar 

  24. Celentano F.C., Gianazza, E. and Righetti, P.G. 1991. On the computational approach to immobilized pH gradients. Electrophoresis 12: 693–703.

    CAS  PubMed  Google Scholar 

  25. Giaffreda, E., Tonani, C. and Righetti, P.G. 1992. pH Gradient simulator for electrophoretic techniques in a Windows environment. J. of Chromatography 630: 313–327.

    CAS  Google Scholar 

  26. Bjellqvist, B., Hughes, G.J., Pasquali, C., Paquet, N., Ravier, F., Sanchez, J.C., Frutiger, S. and Hochstrasser, D. 1993. The focusing positions of polypeptides in immobilized pH gradients can be predicted from their amino acid sequences. Electrophoresis 14: 1023–1031.

    CAS  PubMed  Google Scholar 

  27. Righetti, P.G., Gianazza, E., Bianchi-Bosisio, A., Wajeman, H. and Cossu, G. 1989. ElectrophoreticaUy silent hemoglobin mutants as revealed by isoelectric focusing in immobilized pH gradients. Electrophoresis 10: 595–599.

    CAS  PubMed  Google Scholar 

  28. The automatic Phast Gel System is available from Pharmacia Biotech Inc (Piscataway, NJ).

  29. Fawcett, J.S. and Chrambach, A. 1986. The voltage across wide pH range immobilized pH gradient gels and its modulation through the addition of carrier ampholytes. Electrophoresis 7: 266–272.

    CAS  Google Scholar 

  30. Altland, K., Hackler, R. and Rossman, U. 1986. Avoiding liquid exudation on the surface of rehydrated gels for hybrid isoelectric focusing in carrier ampholyte supplemented immobilized pH gradients. Electrophoresis 7: 251–259.

    CAS  Google Scholar 

  31. Astrua-Testori, S. and Righetti, P.G. 1987. Mechanism of water exudation from mixed-bed ampholine-immobiline gels for isoelectric focusing. J. of Chromatogr. 387: 121–126.

    CAS  Google Scholar 

  32. Altland, K., Becher, P. and Banzhoff A., 1987. Paraffin oil protected high resolution hybrid isoelectric focusing for the demonstration of substitutions of neutral amino acids in denatured proteins: The case of four human transthyretin (prealbumin) variants associated with famillial amyloidotic polyneuropathy. Electrophoresis 8: 293–297.

    CAS  Google Scholar 

  33. Altland, K., Becher, P., Rossmann, U. and Bjellqvist, B. 1988. Isoelectric focusing of basic proteins: The problem of oxidation of cysteins. Electrophoresis 9: 474–485.

    CAS  PubMed  Google Scholar 

  34. Chrambach, A. 1985. The Practice of Quantitative Gel Electrophoresis, VCH Publishers, Weinheim, Germany.

  35. Hanash, S.M., Strahler, J.R., Somerlot, L., Postel, W. and Gorg, A. 1987. Two-dimensional electrophoresis with immobilized pH gradients in the first dimension: Protein focusing as a function of time. Electrophoresis 8: 229–234.

    CAS  Google Scholar 

  36. Vocanson, C., Honnorat,J. Aguera,M. Antoinne,J.C. and Caudie,C. 1994. High resolution two dimensional polyacrylamide gel electrophoresis using immobilines. Application to the study of brain proteins. Cell. Mol. Biol. 40 9–16.

    CAS  PubMed  Google Scholar 

  37. Tissot, J.D., Hohfeld, P., Forestier, F., Tolsa, J.F., Hochstrasser, D.F., Calame, A., Plouvier, E., Bossart, H. and Schneider, P. 1993. Plasma/serum protein patterns in human fetuses and infants: A study by high resolution two dimensional polyacrylamide gel electrophoresis. Applied Theoretical Electrophoresis 3: 183–190.

    CAS  PubMed  Google Scholar 

  38. Fenton, B. 1993. Two-dimensional polyacrylamide gel electrophoresis. Methods Mol. Biol 21: 349–59.

    CAS  PubMed  Google Scholar 

  39. Gorg, A. 1993. Two-dimensional electrophoresis with immobilized pH gradients: Current state. Biochem. Soc. Trans. 21: 130–2.

    CAS  PubMed  Google Scholar 

  40. Gianazza, E., Caccia, P., Quaglia, L. and Righetti, P.G. 1986. Two-dimensional analysis of membrane proteins with isoelectric focusing in immobilized pH gradients in the first dimension. Electrophoresis 7: 537–543.

    CAS  Google Scholar 

  41. Vesterburg, O. 1993. A short history of electrophoretic methods. Electrophoresis 14: 1243–1249.

    Google Scholar 

  42. Hannig, K. 1961. Die Tragerfrie Kontinuierliche Elektrophorese Und Due Anwendung. Z. Anal. Chem. 181: 244–254.

    CAS  Google Scholar 

  43. Bier, M. and Egen, N.B. 1979. In: Developments in Biochemistry. Hagland, H., Westerfield, D. G. and Ball, J. T., (Eds. ). Vol. 7, Elsevier-North Holland, Amsterdam.

    Google Scholar 

  44. Egen, N.B., Twitty, O.E. and Bier, M. 1979. 17th Aerospace Sciences Meeting, New Orleans, LA, Jan. 15–17, document 79-0405.

  45. Hannig, K. and Heidrich, H.G. 1974. The use of continuous preparative freeflow electrophoresis for dissociating cell fractions and isolation of membranous components. Methods in Enzymology 31: 746–761.

    CAS  PubMed  Google Scholar 

  46. Mattock, P. 1980 Velocity gradient stabilized continuous, free flow electrophoresis. A review. Separation and Purification Methods 9: 1–68.

    CAS  Google Scholar 

  47. Naumann, R.J. and Rhodes, P.H. 1984. Thermal considerations in continuous flow electrophoresis. Separation Science and Technology 19: 51–75.

    CAS  Google Scholar 

  48. Bier, M., Egen, N.B., Allgyer, T.T., Twitty, G.E. and Mosher, R. A. 1979 p. 79–89. In: Peptides: Structure and Biological Function, Gross, E. and Meienhofer, J. (Eds. ), Pierce, Rockford, II.

    Google Scholar 

  49. Poux, M. and Bertrand, J. 1990. Preparative free-flow isoelectric focusing: Modeling and experiments. Electrophoresis 11: 907–912.

    CAS  PubMed  Google Scholar 

  50. Bier, M. and Long, T. 1992. Recycling isoelectric focusing: Use of simple buffers. J. of Chromatogr. 604: 73–83.

    CAS  Google Scholar 

  51. Kuhn, R., Hoffstetter-Kuhn, S. and Wagner, H. 1990. Free-flow electrophoresis for the purification of proteins. 2. Isoelectric focusing and field step electrophoresis. Electrophoresis 11: 942–947.

    CAS  PubMed  Google Scholar 

  52. Zheng, S.N., Hanai, T., Yonemoto, T. and Tadaki, T. 1992. Separation of amino acids by recycling free flow electrophoresis. J. Chem. Eng. Japan 25: 686–691.

    CAS  Google Scholar 

  53. Burgand C., Clifton, M.J. and Sanchez, V. 1992. The relative importance of transport phenomena in recycling isoelectric focusing. Electrophoresis 13: 128–135.

    Google Scholar 

  54. Kinsley, K.A. and Rodkey, L.S. 1990. Comparative studies of recycling isoelectric focusing and continuous flow electrophoresis: Separation of proteins with minor charge differences. Electrophoresis 11: 927–931.

    Google Scholar 

  55. Poux, M. and Biscans, J. 1990. Simulation of the isoelectric focusing process in a recycling free-flow cell. Chemical Engineering Research and Design 68: 278–286.

    CAS  Google Scholar 

  56. Ni, J. and Karpas, A. 1983. Isolation of a novel cytotoxic lymphokine (Factor 2) from a human B-cell line (Karpas 160B) by preparative isoelectric focusing in the rotofor cell and chromatofocusing. Cytokine 5: 31–37.

    Google Scholar 

  57. Kirn, H.H.Y. and Jimenez-Ftores, R. 1993. Two-dimensional analysis of skim milk proteins using preparative isoelectric focusing followed by polyacry-lamide gel electrophoresis. J. Food Biochemistry 16: 307–321.

    Google Scholar 

  58. Hjerten, S. and Zhu, M. 1985. Adaptation of the equipment for high-performance electrophoresis to isoelectric focusing. J. of Chromatogr. 346: 265–270.

    CAS  Google Scholar 

  59. Mazzeo, J.R. and Knill, I.S. 1994. Capillary isoelectric focusing of peptides, proteins, and antibodies. Chromatogr. Science Series (Capillary Electrophoresis Technology) 64: 795–818.

    Google Scholar 

  60. Chen, S.M. and Wiktorowicz, J.E. 1992. Isoelectric focusing by free solution capillary electrophoresis. Anal. Biochem, 266: 84–90.

    Google Scholar 

  61. Wu, J. and Pawliszyn, J. 1994. Dual detection for capillary isoelectric focusing with refractive index gradient and absorption. Anal. Chem. 66: 867–873.

    CAS  Google Scholar 

  62. Molteni, S., Frischknecht, H. and Thormann, W. 1994. Application of dynamic capillary isoelectric focusing to the analysis of human hemoglobin variants. Electrophoresis 15: 22–30.

    CAS  PubMed  Google Scholar 

  63. Wu, J. and Pawliszyn, J. 1993. Sensitivity enhancement methods for capillary isoelectric focusing/concentration gradient imaging system. J. of Liquid Chromatogr. 16: 3675–3687.

    CAS  Google Scholar 

  64. Wu, J. and Pawliszyn, J. 1992. Application of capillary isoelectric focusing with universal concentration gradient detector to the analysis of protein samples. J. of Chromatogr. 608: 121–130.

    CAS  Google Scholar 

  65. Yowell, G.G., Fazio, S.D. and Vivilecchia, R.V. 1993. Analysis of a recombinant granulocyte macrophage colony stimulating factor dosage form by capillary electrophoresis, capillary isoelectric focusing and high performance liquid chromatography. J. of Chromatogr. 652: 215–224.

    CAS  Google Scholar 

  66. O'Farrell, P.H. 1985. Separation techniques based on the opposition of two counteracting forces to produce a dynamic equilibrium. Science 227: 1586–1589.

    CAS  PubMed  PubMed Central  Google Scholar 

  67. O'Farrell, P.H. 1981. Method of isotope enrichment, United States Patent 4, 290,855

  68. O'Farrell, P.H. 1982. Method and apparatus for dynamic equilibrium electrophoresis, United States Patent 4,323,439

  69. McCoy, B.J. 1986. Counteracting chromatographic electrophoresis and related imposed-gradient separation process. J. of the Amer. Institute of Chemical Engineers 32: 1570–1573.

    CAS  Google Scholar 

  70. Ivory, C.F. 1987. Continuous counteracting chromatographic electrophoresis, paper number 1064, presented at the 1987 Annual Meeting of the AIChE, New York City, Nov. 15–20.

  71. Hunter, J.B. 1988. An isotachophoretic model of counteracting chromatographic electrophoresis. Separation Science and Technology 23: 913–30.

    CAS  Google Scholar 

  72. Locke, B.R. and Carbonell, R.G. 1989. A theoretical and experimental study of counteracting chromatographic electrophoresis. Separation and Purification Methods 18: 1–64.

    CAS  Google Scholar 

  73. Raj, C.B. Chidambara and Hunter, J.B. 1992. Protein purification by counteracting chromatographic electrophoresis—the focusing window. Bioprocess Engineering 8: 121–128.

    CAS  Google Scholar 

  74. Raj, C.B., 1992. Protein purification by counteracting chromatographic electrophoresis—on the disparity of focusing conditions. Bioseparation 3: 27–36.

    CAS  PubMed  Google Scholar 

  75. Raj, C.B. 1994. Protein purification by counteracting chromatographic electrophoresis: Quantitative focusing limits and protein selection at the interface. J. Biochem. Biophys. Methods 28: 161–172.

    CAS  PubMed  Google Scholar 

  76. Ivory, C.F. and Gobie, W.A. 1990. Continuous counteracting chromatographic electrophoresis. Biotechnology Progress 6: 21–32.

    CAS  Google Scholar 

  77. Giddings, J.C. 1965. Dynamics of chromatography, Vol. I. Marcel Deckker, New York.

    Google Scholar 

  78. Tiselius, A. 1943. Displacement development in adsorption analysis. Ark. Kemi Mineral Geol. 16(18A) 1–11.

    Google Scholar 

  79. Gadam, S., Jayaraman, G. and Cramer, S.M. 1993. Characterization of nonlinear adsorption properties of dextran-based polyelectrolyte displacers in ion exchange systems. J. of Chromatogr. 630: 37–52.

    Google Scholar 

  80. Agosto, M., Wang N.-H.L. and Wankat, P. 1993. Amino acid separation in a multistage fluidized ion exchanger bed. Ind. Eng. Chem. Res. 32: 2058–2064.

    CAS  Google Scholar 

  81. Sluyterman, L.A.E. and Elgersma, O. 1978. Chromatofocusing: isoelectric focusing on ion exchange columns, I. General principles. J. of Chromatogr. 150: 17–30.

    CAS  Google Scholar 

  82. Sluyterman, L.A.E. and Wijdenes, J. 1978. Chromatofocusing: isoelectric focusing on ion exchange columns, II. Experimental verification. J. of Chromatogr. 150: 31–44.

    CAS  Google Scholar 

  83. Sluyterman, L.A.E. and Wijdenes, J. 1981. Chromatofocusing, HI. The properties of a DEAE agarose anion exchanger and its suitability for protein separations. J. of Chromatogr. 206: 429–440.

    CAS  Google Scholar 

  84. Sluyterman, L.A.E. and Wijdenes, J. 1981. Properties of an agarose polyethy-leneimine ion exchanger and its suitability for protein separations. J. of Chromatogr. 206: 441–447.

    CAS  Google Scholar 

  85. Li, C.M. and Hutchens, T.W. 1992. Chromatofocusing. Methods Mol. Biol. 11: 237–248.

    CAS  PubMed  Google Scholar 

  86. Boege, F., Gieseler, F., Biersack, H., Clark, M., Gal, S., Tar, A., Toth-Martinez, B.L. and Hernadi, F.J. 1991. Use of chromatofocusing for separation of beta-lactamases. IX. Analytical chromatofocusing for the separation of a chromosomal cephalosporinase from proteus vulgaris1028. J. of Chromatogr. 545: 189–195

    Google Scholar 

  87. Prepacked chromatofocusing columns and media are commercially available from a number of suppliers including Pharmacia Biotech Inc. (Piscataway, NJ).

  88. Evans, L.L. and Burns, M.A. 1991. The formation and use of stabilized pH gradients in fluidized bed separations. 77d American Institute of Chemical Engineers Annual Meeting, Los Angeles, California.

  89. Rodrigues, A. 1986. Ion Exchange: Science and Technology, Nato ASI Series. Martinus Nijhoff Publishers, Boston, MA.

  90. Stahlberg, J., Johnson, B. and Horvath, C. 1991. Theory for electrostatic interaction chromatography of proteins. Anal. Chem. 63: 1867–1874.

    CAS  PubMed  Google Scholar 

  91. Chen, J., Akiyama, T., Nogami, H., Yagi, J. and Takahashi, H. 1993. Modeling of solid flow in moving beds. ISU International 33: 664–671.

    CAS  Google Scholar 

  92. Crawshaw, J.P., Paterson, W.R., Scott, D.M. and Hart, G. 1992. AIChE Symposium Series (Heat Transfer) 129: 1093–1098.

    CAS  Google Scholar 

  93. Luchesi, P.J., Hatch W.H . Mayer, F. and Rosensweig, R. E. 1979. Magnetically stabilized beds—New gas-solids containing technology. Proc. 10th World Petroleum Congress, Bucharest 4: 419–425.

    Google Scholar 

  94. Rosensweig, R.E., Seigell, J.H., Lee, W.K. and Mikus, T. 1981. Magnetically stabilized fluidized solids. AIChE Symposium Series 77: 8–16.

    CAS  Google Scholar 

  95. Burns, M.A. and Graves, D.J. 1985. Continuous affinity chromatography using a magnetically stabilized fluidized bed. Biotechnology Progress 1: 95–103.

    CAS  PubMed  Google Scholar 

  96. Bums, M.A. and Graves, D.J. 1988. Application of magnetically stabilized fluidized beds to bioseparations. Reactive Polymers 6: 45–50.

    Google Scholar 

  97. Seigell, J.H., Dupre, G.D. and Pirkle, C.J. 1986. Chromatographic separation in a cross-flow MSFB. Chemical Engineering Progress 82: 57–61.

    Google Scholar 

  98. Bellows, R.J., Pirkle, C.J. and Wu, T.D. 1986. Selected applications of magnetically stabilized fluidized beds, Paper 118e, AlChe Meeting, Miami Beach.

  99. Rosenweig, R. E. 1979. Fluidization: Hydrodynamic stabilization with a magnetic field. Science 204: 57–60.

    Google Scholar 

  100. Siegell, J. H. 1987. Liquid-fluidized magnetically stabilized beds. Powder Technology 52: 139–148.

    CAS  Google Scholar 

  101. Higgins, I.R. 1961. Continuous ion exchange equipment… adapted to water and dilute waste treatment. Industrial. Engineering and Chemistry 53: 635–637.

    CAS  Google Scholar 

  102. Higgins, I.R. 1964. Use ion exchange when processing brine. Chemical Engineering Progress 60: 60–63.

    CAS  Google Scholar 

  103. Dormer, K. 1972. Ion exchange principles and applications. P. 42. In: xxx? Ann Arbor Science, Ann Arbor, MI.

    Google Scholar 

  104. Calmon, C. and Gold, A. (Eds.) 1979. Ion Exchange for Pollution Control. CRC Press, Boca Raton. Fl.

    Google Scholar 

  105. Broughton, D.B. 1966. US Patent 3, 291, 726.12

  106. Barker, P.E. 1971. Continuous chromatographic refining. Prog. Separ. Pufir. 4: 325–406.

    CAS  Google Scholar 

  107. Ruthven, D.M. 1984. Principles of Adsorption and Adsorption Processes. Wiley, New York.

    Google Scholar 

  108. Ching, C.B. and Ruthven, D.M. 1985. An experimental study of a simulated countercurrent adsorption system-I. Isothermal steady state operation. Chemical Engineering Science 40: 877–885.

    CAS  Google Scholar 

  109. Ching, C.B. and Ruthven, D.M. 1985. Experimental study of a simulated countercurrent adsorption system-Ill. Sorbex operation. Chemical Engineering Science 40: 1411–1418.

    CAS  Google Scholar 

  110. Balannec, B. and Holier, G. 1993. From batch elution to simulated counter-current chromatography, p. 301–357. In: Preparative and Production Scale Chromatography with Applications, G. Ganetsos and P. E. Barker (Eds. ). Marrcel Dekker, New York.

    Google Scholar 

  111. Nixon, L., Koval, C.A., Xu, L., Noble, R.D. and Slaff, G.S. 1991. The effects of magnetic stabilization on the structure and performance of liquid fluidized beds. Bioseparation 2: 217–230.

    CAS  PubMed  Google Scholar 

  112. Chetty, A.S., Gabis, D.H. and Burns, M.A. 1991. Overcoming support limitations in magnetically stabilized fluidized bed separators. Powder Technology 64: 165–174.

    CAS  Google Scholar 

  113. Burns, M.A. and Graves, D.J. 1988. Structural studies of a liquid-fluidized magnetically stabilized beds—A review. Chemical Engineering Communications 67: 315–330.

    CAS  Google Scholar 

  114. Liu, Y.A., Hamby R.K. and Colberg, R.D. 1991. Fundamental and practical developments of magnetofluidized beds. Powder Technology 64: 3–41.

    CAS  Google Scholar 

  115. Chetty, A.S. and Burns, M.A. 1991. Continuous protein separations in a magnetically stabilized fluidized bed using nonmagnetic supports. Biotechnology and Bioengineering. 38: 963–971.

    CAS  PubMed  Google Scholar 

  116. Evans, L.L. and Burns, M.A. 1993. Support considerations in countercurrent gradient chromatography, 8h AIChE Annual Meeting, St. Louis, MO.

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Evans, L., Burns, M. Solute Focusing Techniques for Bioseparations. Nat Biotechnol 13, 46–52 (1995). https://doi.org/10.1038/nbt0195-46

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