Capillary electrophoresis device with double UV detection and its application to the determination of effective mobilities of peptides.

A new experimental device for high-performance capillary electrophoresis (HPCE) with a double UV detection system and with thermostating of the whole separation compartment was developed. UV detection is doubled by producing two apertures placed symmetrically close to the axis of the optical path of the single-beam UV detector and by the adjustment of the capillary loop on these two apertures. The double-detection system allows exact measurements of electrophoretic and electroosmotic flow velocities. A procedure for the determination of effective mobilities from the data obtained by the double UV detection system was developed and applied to determine the effective mobilities of synthetic peptides (diglycine, triglycine, growth hormone releasing peptide and its derivatives and fragments). The measurements are performed at constant temperature (25°C) and low input power at which temperature increase in the capillary can be neglected and temperature corrections of temperature-dependent magnitudes need not be included in the calculations.