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Figure 1: Stationary phase selectivity can be characterized by looking for column types with varying retention profiles. When com-
pared to a C18, the 4 Restek USLC™ phases offer diverse retention profiles—that is, a true range in selectivity.
Restek USLC™ Phase: PFP Propyl
Properties:
• Increased retention for protonated bases.
• Increased retention for solutes containing dipolar moieties.
• Capable of multi-mode mechanisms.
Relative Retention
Restek USLC™ Phase: IBD
• Increased retention for acids.
• Moderate retention for hydrophobic and dipolar solutes.
• Resistant to dewetting—compatible with 100% aqueous mobile phases.
• Capable of multi-mode mechanisms.
Relative Retention
Restek USLC™ Phase: Biphenyl
• Increased retention for dipolar, unsaturated, or conjugated solutes.
• Increased retention for fused-ring solutes containing electron withdrawing
ring substituents.
• Enhanced selectivity when used with methanolic mobile phase.
Relative Retention
Restek USLC™ Phase: Aqueous C18
• General purpose with a well-balanced retention profile.
• Increased retention for acids and bases.
• Resistant to dewetting—compatible with 100% aqueous mobile phases.
Relative Retention
Restek Phase:C18 Benchmark
• General purpose.
• Strong hydrophobic retention.
Relative Retention
All columns in Figures 1 and 2 were tested using the same silica support.
Figure 2: Restek has extended the selectivity (S) for a range of
columns and defined a set—the 4 USLC™ phases—that is ideal for
fast column selection and faster method development.
All columns were tested using the same silica support.
All columns were tested using the same silica support.
References
[1] L.R. Snyder, J.W. Dolan, P.W. Carr,The Hydrophobic-Subtraction Model of Reversed-
Phase Column Selectivity, J. Chromatogr. A 1060 (2004) 77.
[2] U.D. Neue, J.E. O’Gara, A. Mendez, Selectivity in Reversed-Phase Separations
Influence of the Stationary Phase, J. Chromatogr. A 1127 (2006) 161.
Acknowledgements
The authors gratefully acknowledge the contributions of Dr. Lloyd Snyder from LC
Resources and Dr. Frank Dorman fromThe Pennsylvania State University. The authors
also wish to thank the contributing team of researchers Randy Romesberg, Bruce
Albright, MikeWittrig, Brian Jones, and Vernon Bartlett.
For a detailed analysis of USLC™ column selectivity data, visit
Orthogonal phases
C18 BENCHMARK
Website : E-Mail : TelNo : 03 9762 2034 . . . in AUSTRALIA