A CONDUCTOMETRIC DETECTOR FOR CAPILLARY SEPARATIONS

A simple electrochemical cell has been constructed For conductometric detection in capillary electrophoresis or HPLC. A platinum ring electr ode is chemically deposited at the capillary end and the other electro de, a platinum wire, is immersed, together with the capillary, in a ve ssel containing the running buffer or the mobile phase used. The cell has been tested on a model system and its operational parameters have been discussed, The measurement is very sensitive (a limit of determin ation of ca. 3 x 10(-9) M for potassium ions) and the detector respons e is rapid, comparable with that of the UV photometric detector. The d ynamic range is wide (at least five concentration decades) but is nonl inear at high concentrations.