The Ampiometric Detector

The ampiometric detector is basically an electrochemical device that electrochemically oxidises the migrating band and, while doing so, measures the current required. The applied voltage depends on the solvent and the nature of the material from which the working electrode is fabricated. For example, the useful potential range for glassy carbon electrodes is –0.8 to 1.1 V measured against an Ag/AgCl electrode. As an electrophoretic separation takes place under a high potential gradient, the measuring cell cannot be placed in line with the quartz capillary as a consequence, detectors of this type were operated as an off line device. This procedure was replaced by arranging for the separated zones to be transported into the detector by a short length of silica capillary fused to the separation capillary by a conductive joint made of special type of porous glass. This type of detector can exhibit a very high sensitivity to certain types of solutes, sensitivities achieved being down in the attomol level.