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Modification of ion chromatographic separations by ionic and nonionic surfactants
James S Fritz1, Zhu Yan, Paul R Haddad
1Ames Laboratory, US Department of Energy, Department of Chemistry, Iowa State University, 332 Wilhelm Hall, Ames, IA 50011, USA. kniss@ameslab.gov
Journal of Chromatography. A
|July 2, 2003
Summary
Researchers developed simple methods to modify HPLC columns for efficient ion chromatography (IC) separations. These techniques reduce ion retention times and improve peak sharpness, enhancing analytical capabilities.
Area of Science:
- Analytical Chemistry
- Chromatography
Background:
- High-Performance Liquid Chromatography (HPLC) columns can be modified for Ion Chromatography (IC).
- Ionic surfactant coatings are established for IC, but can lead to long retention times.
Purpose of the Study:
- To investigate simple modifications of standard HPLC columns for efficient IC.
- To reduce ion retention times and improve peak sharpness in IC separations.
Main Methods:
- Permanent coating of HPLC columns with nonionic surfactants or layered coatings.
- Dynamic coating using mobile phase additives like alcohols, diols, or zwitterions.
- Utilizing specific mobile phase compositions with quaternary ammonium cations, zwitterions, and methanesulfonic acid with standard columns.
Main Results:
- Nonionic or layered surfactant coatings significantly reduced ion retention times and sharpened peaks.
- Dynamic coating with mobile phase additives enabled effective separation of alkanecarboxylic acids.
- Specific mobile phase formulations allowed excellent separation of common anions on C18 silica columns and metal ions on cation exchange columns.
Conclusions:
- Simple modifications to ordinary HPLC columns can achieve efficient ion chromatography.
- These methods offer practical alternatives for enhancing IC separations without specialized columns.
- The developed techniques provide improved detection limits and analytical performance for various ionic species.