, Volume 55, Issue 9–10, pp 555–563 | Cite as

Phase ratio and eluotropic strength changes on retention variations in subcritical fluid chromatography (SubFC) using packed octadecyl columns

  • E. Lesellier
  • K. Gurdale
  • A. Tchapla
Originals Column Liquid Chromatography


In SubFC, using packed octadecyl columns, different retention variations occur when a modifier (methanol or acetonitrile) is added to carbon dioxide. A study of these variations was carried out by using alkylbenzene homologues as probes. An experimental design has been developed to describe the retention behaviorvs modifier percentage, outlet pressure and temperature.

The retention in SubFC was found to be govemed mainly by the modifier percentage and the temperature, regardless of the modifiers used, and to follow a quadratic mathematical model.

For both tested modifiers, different retention behavior was observed depending on the alkyl chain length. Retention of the small homologues is ruled by the changes of the phase ratio. These changes are due to either adsorption/desorption of the mobile phase onto the stationary phase or to mobile phase density variations. Retention of the longest homologues does not depend on the phase ratio but is govemed by the eluotropic strength, i.e., by modification of the solute solubility in the mobile phase.

On the other hand, temperature induces mainly solubility modifications when pressure acts through density variations with low modifier percentages, or through eluotropic strength variation with high modifier percentages.

However, differences in retention behavior between this homologous series and high molecular mass compounds, as well as with methanol and acetonitrile, underline that a retention model based on a compound family used as probes may sometimes be, unable to describe the behavior of other compounds.

Finally, the additional calculation of efficiency and resolution enabled choice of different mobile phases to achieve a better separation of alkybenzenes.

For these compounds and for those differing in the hydrophobic chain length, resolution depends rather more on selectivity than on efficiency. Moreover, for identical separation levels, the use of acetonitrile is suggested to obtain lower retention times.

Key Words

Column liquid chromatography Subcritical fluid chromatography Eluotropic strength changes Retention behaviors Homologous series 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. [1]
    Martire, D.E.; Boehm, R.D.J. Phys. Chem. 1987,91, 2433.CrossRefGoogle Scholar
  2. [2]
    Chester, T.L.; Innis, D.P.H.R.C. and C.C. 1985,8, 56.Google Scholar
  3. [3]
    Berger, T.A. inPacked Column SFC, Smith R.M. Ed., Royal Society of Chemistry, Cambridge, UK,1995.Google Scholar
  4. [4]
    Berger, T.A.J. High Resol. Chromatogr. 1991,14, 312.CrossRefGoogle Scholar
  5. [5]
    Lesellier, E.; Krstulovic, A.M.; Tchapla, A.Chromatographia 1993,36, 275.CrossRefGoogle Scholar
  6. [6]
    Berger, T.A.; Deye, J.F.J. Chromatogr. Sci. 1991,29, 280.Google Scholar
  7. [7]
    Janssen, H.G.; Schoenmackers, P.J.; Cramers, C.A.J. Chromatogr. 1991,552, 527.CrossRefGoogle Scholar
  8. [8]
    Berger, T.A.; Deye, J.F.J. Chromatogr. 1991,547, 377.CrossRefGoogle Scholar
  9. [9]
    Berger, T.A.; Deye, J.F.J. Chromatogr. Sci. 1991,29, 390.Google Scholar
  10. [10]
    Lockmuller, C.H.; Mink, L.P.J. Chromatogr. 1989,471, 357.CrossRefGoogle Scholar
  11. [11]
    Strubinger, J.R.; Song, H.; Parcher, J.F.Anal. Chem. 1991,63, 98.CrossRefGoogle Scholar
  12. [12]
    Strubinger, J.R.; Song, H.; Parcher, J.F.Anal. Chem. 1991,63, 104.CrossRefGoogle Scholar
  13. [13]
    Gurdale, K.; Lesellier, E.; Tchapla, A.Anal. Chem. 1999,71, 2164.CrossRefGoogle Scholar
  14. [14]
    Gurdale, K.; Lesellier, E.; Tchapla, A.J. Chromatogr. A 2000,866, 241.CrossRefGoogle Scholar
  15. [15]
    Berger, T.A.; Deye, J.F.Anal. Chem. 1990,62, 1181.CrossRefGoogle Scholar
  16. [16]
    Upmoor, D.; Brunner, G.H.Chromatographia 1992,33, 261.CrossRefGoogle Scholar
  17. [17]
    Lesellier, E.; Tchapla, A. inSupercritical Fluid Chromatography with Packed Columns, Anton, K.; Berger, C. Eds., Marcel Dekker, Inc., New York,1998.Google Scholar
  18. [18]
    Lesellier, E.; Tchapla, A.Anal. Chem. 1999,71, 5372.CrossRefGoogle Scholar
  19. [19]
    Lesellier, E.; Bleton, E.; Tchapla, A.Anal. Chem. 2000,72, 2573.CrossRefGoogle Scholar
  20. [20]
    Lesellier, E.; Gurdale, K.; Tchapla, A.22 Int. Symposium on Chromatography. Rome, 13–18 September,1998, 570.Google Scholar
  21. [21]
    Deye, J.F.; Berger, T.A.; Anderson, A.G.Anal. Chem. 1990,62, 615.CrossRefGoogle Scholar
  22. [22]
    Cantrell, G.O.; Stringham, R.W.; Blackwell, J.A.; Wechwerth, J.P.; Carr, P.W.Anal. Chem. 1996,68, 3645.CrossRefGoogle Scholar
  23. [23]
    Blackwell, J.A.; Stringham, R.W.; Wechwerth, J.P.Anal. Chem. 1977,69, 409.CrossRefGoogle Scholar
  24. [24]
    Gurdale, G.; Lesellier, E.; Tchapla, A.22 Int. Symposium on Chromatography, Rome, 13–18, September,1998, 347.Google Scholar
  25. [25]
    Levy, J.M.J. High Resol. Chromatogr. 1987,10, 493.CrossRefGoogle Scholar
  26. [26]
    Lesellier, E.Analusis,1999,27, 241.CrossRefGoogle Scholar

Copyright information

© Friedr. Vieweg & Sohn Verlagsgesellschaft mbH 2002

Authors and Affiliations

  • E. Lesellier
    • 1
  • K. Gurdale
    • 1
  • A. Tchapla
    • 1
  1. 1.Groupe de Chimie Analytique de Paris Sud, LETIAMIUT Orsay, Plateau de MoulonOrsayFrance

Personalised recommendations