Chromatographia

, Volume 52, Issue 5–6, pp 325–333

Chromatographic behaviour of low molar-mass polyesters in normal-phase high-performance liquid chromatography

  • H. J. A. Philipsen
  • H. A. Claessens
  • P. Jandera
  • M. Bosman
  • B. Klumperman
Originals Column Liquid Chromatography

Summary

The normal-phase chromatographic retention behaviour of polyesters on bare silica and on a polymer-based polyamine (PA) column has been studied with a variely of binary mobile phases under isocratic conditions. The dependence of experimental retention data on the degree of polymerization (p) and on mobile phase composition (φ) was characterized by to an approach developed by Jandera et al. The bulky repeating unit and the relatively highly polar end groups of the polyesters both had a large influence on retention behaviour. The two effects in combination explain the molar-mass-independent retention observed experimentally at a particular mobile phase composition for all the mobile phase—stationary phase combinations investigated. These conditions were found to be independent of the type of end group. End group separation on a silica column improves when the polarity of the less polar solvent is increased. End group separation is better on the PA column because of a greater difference between the adsorption energy of the alcohol and acid end groups. Better prediction of retention data on the PA column was achieved by use of an approach which assumes two different types of adsorption site. Results enabled further understanding of retention behaviour in normalphase gradient polymer-elution chromatography (NPGPEC) and explained both the dependence of the order of elution onp and differences between the end-group selectivity of different systems.

Key Words

Column liquid chromatography Normal-phase isocratic elution Normal-phase gradient elution Polyester resins 

Symbols

A0

Adsorbed area of an end group

A1

Adsorbed area of a repeating unit

KD

Chromatographic distribution coefficient

ka0

Retention factor of an end group for 100% less polar solvent, A

ka1

Retention factor of a repeating. unit for 100% less polar solvent, A

k0

Retention factor at the coelution concentration

k01,k02

Retention factors for adsorption sites 1 and 2 for 100% polar solvent B

nb

Adsorbed area of a polar solvent molecule

Q0

Adsorption energy of an end group for pentane as mobile phase

Q1

Adsorption energy of a repeating unit for pentane as mobile phase

Va

Volume of the adsorbed solvent monolayer per unit weight of adsorbent

α1,α2

Partial retention factors for the repeating units on adsorption sites 1 and 2

α

Activity of the adsorbent

β1,β2

Partial retention factors for the end groups on adsorption sites 1 and 2

εa

Polarity of the less polar solvent, A

εb

Polarity of the polar solvent, B

ϕ0

Volume fraction of the polar solvent B in the mobile phase at the coelution point

φ1,φ2

Partial phase ratios for adsorption sites 1 and 2

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Copyright information

© Friedr. Vieweg & Sohn Verlagsgesellschaft mbH 2000

Authors and Affiliations

  • H. J. A. Philipsen
    • 1
  • H. A. Claessens
    • 2
  • P. Jandera
    • 4
  • M. Bosman
    • 3
  • B. Klumperman
    • 3
  1. 1.Océ Technologies, Research and Development departmentVenloThe Netherlands
  2. 2.Laboratory of Instrumental AnalysisEindhoven University of TechnologyEindhovenThe Netherlands
  3. 3.Laboratory of Polymer ChemistryEindhoven University of TechnologyEindhovenThe Netherlands
  4. 4.Faculty of Chemical TechnologyUniversity of PardubicePardubiceCzech Republic

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