Improved capacitively coupled conductivity detector for capillary electrophoresis

Abstract

The new features of the capacitively coupled contactless conductivity detector for capillary electrophoresis described are higher peak-to-peak excitation voltages for the detector cell of up to 250 V, a pick-up amplifier in close proximity to the electrode and synchronous detection. The electrical performance of the cell was characterized and found to follow readily predictable patterns. The alterations led to a higher signal strength, a better signal-to-noise ratio (S/N) and improved stability. The 3 × S/N detection limits obtained for inorganic cations and anions are in the range 0.1–0.2 μM. For the indirect detection of model compounds of organic cations and anions (aliphatic amines and sulfonates), detection limits of typically 1 μM were achieved.