It is generally used for separating ions, which move at different speeds when the voltage is applied depending on their size and charge. The solutes are seen as peaks as they pass through the detector and the area of each peak is proportional to their concentration, which allows quantitative determinations. Analysis includes purity determination, assays, and trace level determinations. Analysis times are in the region of 1-30 minutes depending on the complexity of the separation. Modern instruments are relatively sophisticated and may contain fibre optical detection systems, high capacity autosamplers, and temperature control devices.
Detection is usually by UV absorbance - often with a diode array.
Other commercial detectors include fluorescence detection and coupling to mass spectrometers. Inorganic ions CE can rapidly and efficiently separate inorganic ions such as metal ions and anions, for example chloride, sulphate and nitrate. These species have no chromophore and cannot be detected using conventional UV absorbance. To get round this problem, analysts use indirect UV detection, by adding a UV absorbing species to the electrolyte to give a large background signal. This signal decreases when the inorganic ions pass through the detector, which generates negative peaks.