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Practical observations on the performance of bare silica in hydrophilic interaction compared with C18 reversed-phase liquid chromatography

Heaton, James C.; Wang, Xiaoli; Barber, William E.; Buckenmaier, Stephan M.C.; McCalley, David V.

Practical observations on the performance of bare silica in hydrophilic interaction compared with C18 reversed-phase liquid chromatography Thumbnail


Authors

James C. Heaton

Xiaoli Wang

William E. Barber

Stephan M.C. Buckenmaier



Abstract

The kinetic performance of a bare silica and C18 phase prepared from the same sub-2. μm and 3.5. μm base materials were compared in the HILIC and RP mode using both charged and neutral solutes. The HILIC column was characterised using the neutral solute 5-hydroxymethyluridine, the weak base cytosine, and the strong base nortriptyline, the latter having sufficient retention also in the RP mode to allow comparison of performance. Naphthalene was also used as a simple neutral substance to evaluate the RP column alone. The retention factors of all substances were adjusted to give similar values (k'. ~. 5.5) at their respective optimum linear velocities. Reduced van Deemter b-coefficients (determined by curve fitting and by the peak parking method, using a novel procedure involving switching to a dummy column) were significantly lower in HILIC for all substances compared with those found under RP conditions. Against expectation, c-coefficients were always lower in RP when compared with HILIC using sub-2. μm particles. While measurement of these coefficients is complicated by retention shifts caused by the influence of high pressure and by frictional heating effects, broadly similar results were obtained on larger particle (3.5. μm) phases. The mechanism of the separations was further investigated by examining the effect of buffer concentration on retention. It was concluded that HILIC can sometimes show somewhat inferior performance to RP for fast analysis at high mobile phase velocity, but clearly shows advantages when high column efficiencies, using longer columns at low flow velocity, are employed. The latter result is attributable to the lower viscosity of the mobile phase in HILIC and the reduced pressure requirement as well as the lower b-coefficients. © 2014 David V. McCalley.

Journal Article Type Article
Publication Date Feb 7, 2014
Journal Journal of Chromatography A
Print ISSN 0021-9673
Electronic ISSN 1873-3778
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 1328
Pages 7-15
APA6 Citation Heaton, J. C., Wang, X., Barber, W. E., Buckenmaier, S. M., & McCalley, D. V. (2014). Practical observations on the performance of bare silica in hydrophilic interaction compared with C18 reversed-phase liquid chromatography. Journal of Chromatography A, 1328, 7-15. https://doi.org/10.1016/j.chroma.2013.12.058
DOI https://doi.org/10.1016/j.chroma.2013.12.058
Keywords HILIC, retention mechanism, peak parking, b-term, c-term
Publisher URL http://dx.doi.org/10.1016/j.chroma.2013.12.058

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