MIPs logo MIPdatabase      MIP2020 Conference logo Use this space
Custom Search
Reference type: Journal
Authors: Ansell RJ, Kuah KL
Article Title: Imprinted polymers for chiral resolution of (+/-)-ephedrine: understanding the pre-polymerisation equilibrium and the action of different mobile phase modifiers.
Publication date: 2005
Journal: Analyst
Volume: 130
Issue: (2)
Page numbers: 179-187.
DOI: 10.1039/b408751h

Abstract: A thorough study has been made of the ephedrine-methacrylic acid (MAA) system for molecular imprinting, involving NMR studies of the pre-polymerisation equilibria, modelling and HPLC enantioseparations with different mobile phases. When dimerisation of MAA is accounted for, NMR titrations demonstrate there is a very strong ('stoichiometric', K 10000 M-1) interaction between ephedrine and a single MAA monomer. Polymers prepared with a 1 : 1 monomer : template ratio are capable of enantioseparation, indicating, in combination with the NMR results, that the 1 : 1 interaction probably involves the carboxylic acid acting as a chelating monomer, forming hydrogen bonds to both the template amine and hydroxyl moieties. Higher monomer : template ratios cause further changes in the NMR signals, suggesting at least one further MAA can interact with the amine group, with a weaker association constant (K 80 M-1). Polymers prepared with a 4 : 1 monomer : template ratio are thus proposed to contain a mixture of 1-monomer binding sites and 2-monomer binding sites, the latter being of enhanced acidity. In HPLC, better results are obtained with the 4 : 1 polymer using acetic acid as a modifier, while better results are obtained for the 1 : 1 polymer using butylamine as a modifier. We propose a model whereby acetic acid exerts its effect by reducing binding to the 1-monomer sites, while butylamine works largely through blocking the most acidic, 2-monomer sites. For preparative chromatography we suggest the 1 : 1 polymer, with a larger population of weaker but more uniform binding sites, is most promising.
Template and target information: ephedrine

  Periodic table Banana Split - the chemical formula for banana split shirt  Mug featuring the name Richard spelled out in the single letter amino acid code  Meerkat somebody mention coffee mug

Molecules Special Issue call      Appeal for information


Join the Society for Molecular Imprinting
Logo of the Society for Molecular Imprinting

New items RSS feed
new items RSS feed  View latest updates

Sign-up for e-mail updates:
Choose between receiving an occasional newsletter or more frequent e-mail alerts.
Click here to go to the sign-up page.

Is your name elemental or peptidic? Enter your name and find out by clicking either of the buttons below!
Other products you may like:
view listings for MIP books on eBay:

Mickey Mouse 90th Anniversary banner