Separation of nucleoside mono-, di- and triphosphates by capillary electrophoresis via cadmium complexation

The CE separation of twelve nucleotides (5'-mono-, di-, triphosphates of ad enosine, guanosine, cytidine and uridine) was improved by adding cadmium io n to the ammonium citrate/citric acid buffer (pH 5, ionic strength 100 mM). Cadmium ion acts as a complexing agent for some nucleotides (ATP, CTP, GTP , UTP, GDP). In order to accelerate the separation, the electroosmotic flow was reversed by flushing the fused-silica capillary with 0.2 % aqueous sol ution of the polycationic surfactant hexadimethrine bromide. A good separat ion of the twelve nucleotides studied was then achieved on a dynamically co ated capillary in less than 5 min by using an ammonium citrate/citric acid buffer (pH 5, ionic strength 100 mM) to which 2 mM cadmium ion has been add ed. High peak efficiencies were obtained (210 000 theoretical plates) and t he resolution between two adjacent peaks was always greater than 1.5.