Electrochemical Detectors:

These can be used only if solute molecules in aqueous and aqueous-organic phase have voltammeteric characteristics. These are of several types depending on amperometry, polarography, coulometry and conductometry. Electrochemical detectors have not been exploited to the extent of optical detectors though these have advantage of being easy, highly sensitive, convenient and huge spread applicability. A variety of HPLC/ electrochemical detectors are available commercially. These are potential universal detectors for fulfilling long time need. A typical thin layer amperometer detector is shown in Figure. It can measure nanoampere level current at a controlled potential as a function of time and consists of a flow cell in a 50 µ m

Figure: A Schematic diagram of an amperometric thin layer detector for HPLC

thick polyfluorocarbon gasket sandwiched between two blocks, one plastic and the other stainless steel. The working electrode of Pt, Au, glassy carbon or a carbon paste is placed on one side of the channel and a reference electrode (usually Ag/AgCl) is connected to the working region by tubing. Its cell volume is 1-5µ L.