Macrocyclic polyamine as a selective modifier in a bonded-phase capillary column for the electrophoretic separation of aromatic acids

The use of a macrocyclic polyamine, 28[ane]-N6O2, as a selective modifier in a bonded-phase capillary column for the electrophoretic separation of 14 aromatic acids is described. Parameters that affect the performance of the separations, such as the type Of buffer, the pH and concentration of buffer, the applied potential and the injection mode were studied. By changing the buffer pH (4.0-5.0), buffer concentration (10-50 mM) and applied potential (-10 similar to -20 kV), optimum conditions were obtained at -20 kV, using an acetate buffer (20 mM, pH 4.5), hydrodynamic injection with a vacuum at the buffer reservoir on the detector side and detection at 220 nm. The results showed that the separation was effective under these conditions. The plate number was greater than 4.10(4) m(-1). Due to the wide variation in the mobilities of the test compounds, injection studies suggested that a vacuum at the buffer reservoir on the detector side would produce a result that is more representative of the initial sample composition. Benzoic acid in soy sauce, salicylic acid in Salic ointment and Aspirin were sampled and analyzed using the established conditions. (C) 1999 Elsevier Science B.V. All rights reserved.