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Column selectivity in reversed-phase liquid chromatography. VII. Cyanopropyl columns
D H Marchand1, K Croes, J W Dolan
1Department of Chemistry, University Wisconsin-River Falls, River Falls, WI 54022, USA.
Journal of Chromatography. A
|February 1, 2005
Summary
Cyanopropyl (cyano) columns exhibit lower hydrophobicity and steric hindrance than traditional alkyl-silica columns. Adjusting mobile phases is crucial for comparable sample retention when switching to cyano columns for chromatography.
Area of Science:
- Analytical Chemistry
- Chromatography
Background:
- Cyanopropyl (cyano) columns are a type of stationary phase used in chromatography.
- Traditional alkyl-silica columns, such as C8 and C18, have different properties compared to cyano columns.
Purpose of the Study:
- To characterize eleven cyanopropyl columns using established relationships for alkyl-silica columns.
- To compare the properties of cyano columns with type-B alkyl-silica columns.
Main Methods:
- Characterization of cyano columns using a model developed for alkyl-silica columns.
- Evaluation of hydrophobicity (H), steric hindrance (S*), and hydrogen-bond acidity (A) of cyano columns.
Main Results:
- Cyano columns demonstrate significantly lower hydrophobicity (H), steric hindrance (S*), and hydrogen-bond acidity (A) compared to type-B alkyl-silica columns.
- Sample retention (k) is generally weaker on cyano columns, necessitating weaker mobile phases for comparable retention.
Conclusions:
- The unique properties of cyano columns require careful consideration of mobile phase adjustments for method development.
- Practical selectivity comparisons between cyano and other columns must account for both column and mobile phase changes.