Electrophoretic separations with polyether ether ketone capillaries and capacitively coupled contactless conductivity detection

Polyether ether ketone (PEEK) capillaries were found to be compatible with capacitively-coupled contactless-conductivity detection (C4D). Detection limits in the order of 10−7 M were obtained with C4D employing a high excitation voltage (HV-C4D) for inorganic cations and anions. The organic polymer capillary shows a relatively low electroosmotic flow of 2.6·10−4 cm2 V−1 s−1. Thus inorganic anions and slower organic anions can be separated with a PEEK capillary in a single run without flow modifier. This feature also enables the analysis of both, cations and (fast and slow) anions, in a sample in two subsequent runs just by reversing the polarity or in a single run if dual opposite end injection is employed.