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Breakthrough of polymers in interactive liquid chromatography.
Xulin Jiang1, Aschwin van der Horst, Peter J Schoenmakers
1Polymer-Analysis Group, Department of Chemical Engineering, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands. xljiang@science.uva.nl
Journal of Chromatography. A
|December 20, 2002
Summary
A breakthrough peak in polymer HPLC is explained: two peaks represent the entire sample, not different fractions. This phenomenon can jeopardize quantitative polymer analysis, but methods exist to avoid it.
Area of Science:
- Polymer Chemistry
- Analytical Chemistry
- Chromatography
Background:
- Narrow polymer standards in High-Performance Liquid Chromatography (HPLC) often exhibit two distinct peaks.
- One peak appears at the solvent front (breakthrough peak), while the second is significantly retained.
- The underlying reasons for this dual-peak phenomenon have remained unexplained despite prior observations.
Purpose of the Study:
- To provide a rigorous explanation for the observed breakthrough peak in polymer HPLC.
- To clarify that both peaks represent the entire polymeric sample, not different molecular weight fractions.
- To investigate factors influencing the breakthrough peak and offer solutions for accurate polymer quantification.
Main Methods:
- Investigated the breakthrough peak phenomenon using narrow polymer standards (polystyrene, poly(methyl methacrylate)).
- Conducted experiments under various conditions: isocratic and gradient HPLC, different sample solvents, mobile phase compositions, injection volumes, concentrations, column temperatures, and analyte properties.
- Analyzed the impact of these variables on the formation and intensity of the breakthrough peak.
Main Results:
- Demonstrated that both the breakthrough peak and the retained peak represent the entire polymer sample.
- Identified that the breakthrough peak's variable contribution can compromise quantitative polymer analysis.
- Determined the effects of sample solvent, mobile phase, injection parameters, temperature, and analyte characteristics on the breakthrough peak.
Conclusions:
- The breakthrough phenomenon in polymer HPLC is fully explained, clarifying the nature of the dual peaks.
- Established three necessary and sufficient conditions for the occurrence of the breakthrough peak.
- Provided practical recommendations and a structured method for selecting optimal sample solvents to avoid the breakthrough peak and ensure accurate polymer quantification.