Use of calixarene compounds as selectivity modifiers in capillary electrophoresis separations

The use of calixarene compounds as selectivity modifiers and potassium bromide as electrolyte in capillary electrophoresis (CE) was studied. Calixarenes are macrocyclic oligomers having the shape of a conical vase whose inner cavity can accommodate various guest molecules. These compounds absorb in the ultraviolet region, with maxima at approximately 204 nm, and can be employed for the indirect determination of various types of compounds. The use of water soluble sulphonated calixarene as mobile phase in combination with different salts allowed us to develop electrophoretic methods for the determination of special compounds which are transparent in the UV region. The potential of this buffer was assessed by separating various groups of analytes including amino acids, biogenic amines and inorganic cations and anions. A system consisting of seven amino acids, used as model compounds, was chosen to optimize the buffer. The different instrumental variables affecting sensitivity and resolution of the mixture were carefully optimized. (C) 1998 Elsevier Science B.V. All rights reserved.