What is electrochemical detection?
Electrochemical detection (ECD) for HPLC or uHPLC is a selective and extremely sensitive detection technique that is applied in a number of analyses such as neurotransmitters, catecholamines, aminoglycosides, carbohydrates, thiols and phenols. For detection, flow cells and electrodes are used that can be miniaturized, making it suitable for standard- to nano-HPLC. In combination with the proper electronics, ECD has an enormous linear dynamic range of more then 7 orders of magnitude. This means that concentrations can be measured linearly from 10 pmole/L to 100 µmol/L with the same instrument.
HPLC with an electrochemical detector.
How does electrochemical detection work?
In amperometric electrochemical detection the electrical current is measured resulting from oxidation or reduction reactions (see video). A sample is introduced in HPLC and separated on the chromatographic column. The column is connected to an ECD cell, which is an electrochemical sensor where a reaction takes place at an electrode. Electrochemically active substances that elute from the column undergo an electrochemical reaction, electrons are transferred resulting in an electrical current. The electrodes are connected to an electronic circuitry with a powerful -low noise- amplifier that converts a pico- or nanoampere current in a detectable signal for data acquisition.