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  Global Journal of Analytical Chemistry. Volume 1, Issue 3 (2010) pp. 228-232
  Research Article
 
Dopa and tyrosine enantiomers migration order reversal using uncoated and polypyrrole coated capillaries
  Radim Knob*, Vítezslav Maier, Václav Ranc, Joanna Znaleziona, Juraj Ševcík  
     
Department of Analytical Chemistry, Fakulty of Science, Palacký University in Olomouc, Trída 17. Listopadu 12, CZ-77146 Olomouc, Czech Republic
   
  Abstract  
  A simple method for reversing migration order of enantiomers is presented. An uncoated and polypyrrole coated capillary modified with dextran sulfate (PP/DS) are used in the background electrolyte of low pH, resulting in different velocities of the electroosmotic flow. An enantioseparation of D,L-Dopa and D,L-tyrosine as model analytes is shown utilizing sulfated-ß-cyclodextrin as the chiral selector. Reversal of migration order was achieved in the two different capillaries by applying voltage of opposite polarities in each capillary. The best separation conditions were 0.02 mol.L-1 phosphoric acid (pH 2.0) and 2% S-ß-CD for both capillaries. A study of repeatabilities was done, showing better values for PP/DS (intraday below 2% RSD, interday below 3% RSD) than the uncoated capillary (intraday around 4% RSD, interday around 5% RSD). The approach could be applied to reversal of migration of other cationic or anionic solutes at low pH.
     
  Keywords  
  Enantioseparation; DOPA; Tyrosine; Sulfated-ß-cyclodextrin; Capillary coating; Polypyrrole  
     
   
   
   
   
     

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