Chromatography Research Today is a free monthly online journal that collates and summarizes the latest research about Chromatography, including details on column chromatography, gas chromatography (gc), liquid chromatograpy, hplc.

The effect of chaotropic mobile phase additives on the separation of selected alkaloids in reversed-phase high-performance liquid chromatography.

Flieger J

Department of Inorganic and Analytical Chemistry, Medical University of Lublin, 20-081 Lublin, Staszica 6, Poland. jflieger@am.lublin.pl

The retention behavior of selected alkaloids from different classes was studied. The effect of chaotropic salts additives to the mobile phase on chromatographic parameters of protonated basic analytes was investigated on Zorbax Extend-C18 column. The influence of the type of salts and their concentration on retention, efficiency, peak symmetry and separation selectivity of investigated alkaloids was established. Buffered acetonitrile-water mobile phase was chosen because of significant retention of added liophilic ions due to strong dispersive pi-pi interactions. These conditions are responsible for great contribution of electrostatic forces in the retention of protonated bases. The addition of salt, such as hexafluorophosphate, perchlorate, trifluoroacetate leads to the increase in retention, efficiency and separation selectivity of examined analytes. The influence of added salts on increase in retention parameters could be expressed as follows: H2PO4- < CF3COO- < ClO4- < PF6-. This order is in agreement with ability of salts to "salting-in" effect according to Hofmeister series. Obtained chromatograms of alkaloids mixture illustrate suitability of chaotropic effect to improve their separation selectivity.

Published 17 April 2006 in J Chromatogr A, 1113(1): 37-44.
Full-text of this article is available online (may require subscription).

© 2005-2008 Chromatography Research Today. All Rights Reserved.