36
August/September 2011
“Advances in Separation Science”
The Chromatographic Society Spring Symposium 2011
Held at Novartis Institute for Biomedical Research, Horsham, West Sussex, Wednesday and Thursday 11th-12th May 2011 Review by Pauk Ferguson and John Lough
As delegates weaved their way through leafy West Sussex on the morning of 11th May it was a bright sunny day. These were gloomy times though for R&D in major UK pharma but to all intents and purposes it was just like any other ChromSoc Spring Symposium at a major pharmaceutical site. There was a buzz in the air with just over 100 delegates attending and lively networking taking place in the exhibition area (15 exhibitors and/or sponsors: Waters (Gold Sponsors), Agilent Technologies, ARC Sciences, Chemputeam SA, Chiral Technologies, Crawford Scientific, Dionex (UK), Dynamic Extractions, Gilson Scientific, Hichrom, International Labmate, Sigma Aldrich, Thermo Fisher Scientific, TTP LabTech, VWR International) as everyone eagerly anticipated the next day-and-a-half’s proceedings. The theme was “Advances in Separation Science” but given the nature of the venue the emphasis was on advances in separation science apertaining to early Drug Discovery.
The show began with the heavy artillery up front. ChromSoc Martin Medallist, Professor Wolfgang Lindner (University of Vienna, Austria) gave the opening lecture on “Enantiomer Separations with Chiral Ion Exchangers, a Unique Class of Chiral Columns”. Professor Lindner began with an elegant philosophical discourse on enantiomer separations, covering multiple- site interactions, modelling and the free energy differences needed to bring about some enantioselectivity and the need to strike a balance so that stereospecific interactions were not swamped by non- stereospecific ones. He continued with a justification for the use of quinine/quinidine basis for the range of niche’ chiral anion- exchangers that his group has produced over the years (commercially available e.g. as QD-AX from Chiral Technologies). These show broad enantioselectivity for chiral organic acids. Buffer salts in the mobile phase act as competing ions and accordingly do not affect enantioselectivity but can be used to moderate retention. In general, if an optimised chiral separation is obtained for one organic acid, these conditions tend to be less suitable for other organic acids. He described how, since carbon dioxide acts as a weak acid, some of these phases, such as WAX QD-1, can be used for chiral SFC
Novartis, Horsham
without any modifiers in the mobile phase. He then went on to describe how his group had used the principle of microscopic reciprocity to develop chiral cation exchange phases. These have been shown to be useful for amino-alcohols such as clenbuterol and for some very polar chiral compounds. In the final phase of the presentation, Professor Lindner described the most recent of his groups chiral stationary phases (CSP) that had been commercialised i.e. zwitterionic phases containing a sulphonic acid group as well as a quinine/quinidine moiety. These work for acids, bases and zwitterions, albeit the cation exchange phases work better for
bases. The zwitterionic CSP have been used for screening amino acids and give particularly good enantioseparations for derivatised amino acids. When the sulphonic acid group is on an extended chain, chiral separation may be had for peptides and peptidomimetics where the chiral centres are quite far apart. A final application described was the use of the zwitterionic phases for the study of conformational isomerism.
Also in the opening session, Professor Jeremy Glennon (University College Cork, Eire) presented on “ Recent Progress in Supercritical Functionalisation and
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