Liquid Chromatography Detectors - The Electrochemical Detector > Basic Electrochemical Detector Electronics > Page 93

Basic Electrochemical Detector Electronics

A simplified form of the circuit that is in general use is shown in figure 58.

Figure 58 Basic Circuit Used with Electrochemical Detectors

The amplifiers can best be considered as FET operational amplifiers such as the TLO81. The auxiliary electrode is held at a fixed potential by the first amplifier, the voltage being selected by the potentiometer (P) that is connected to a regulated power supply. The current flowing through the working electrode is processed by the second amplifier and the output fed to the recorder or data acquisition system. The electrochemical detector as described is extremely sensitive but has certain disadvantages.

The mobile phase must be extremely pure, oxygen free and devoid of metal ions.