SEPARATION OF METAL-CATIONS BY ELECTROPHORESIS IN A POSITIVELY CHARGED COATED CAPILLARY

In the expanding field of capillary electrophoresis, the use of coated capillaries is becoming more widespread. Application of a thin polyme r coating on the surface of the silica capillary wall makes it possibl e to generate a capillary wall of positive or no charge when using a t ypical buffer of a pH of 5.0 to ca. 6.0, thereby altering the electroo smotic flow. Indeed, when a coating is used which carries a positive c harge under appropriate buffer conditions, the electroosmotic flow is reversed from the normal direction. This reversal increases the migrat ion times of metal cations and also improves separation efficiency. In this work, a positively charged coated capillary was used with a 2-am inopyridine buffer system for the separation of metal cations. Separat ions using this system compared favorably with other published results . The positively charged coated column yielded cation separations supe rior to those obtained with uncoated columns. This system proved effec tive for the separation of many cations, including lanthanides.