A conductometric detector for capillary separations

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Abstract
A simple electrochemical cell has been constructed for conductometric detection in capillary electrophoresis or HPLC. A platinum ring electrode is chemically deposited at the capillary end and the other electrode, a platinum wire, is immersed, together with the capillary, in a vessel 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 determination of ca. 3 × 10−9 M for potassium ions) and the detector response is rapid, comparable with that of the UV photometric detector. The dynamic range is wide (at least five concentration decades) but is nonlinear at high concentrations.