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Reference
Electrode
(installed inside
cylinder)
Cell Body
(counter-
electrode)
The reference electrode is chosen so that the potential difference between it and
the solution is fixed by an electrochemical redox couple. There are two modes of
potential referencing: Ag/AgCl and pH–Ag/AgCl. See Section 2.4.1 for details.
Cell Design
The Dionex ED50A amperometry cell is a thin-layer design. Mobile phase flows
in a thin channel parallel to the surface of a flat disk electrode. The resulting
smooth flow minimizes noise. The low volume (0.2
operation with high efficiency, narrow bore columns. The cell design minimizes
the electrical resistance between the working electrode and the counterelectrode
by locating the counterelectrode (the titanium cell body) directly across the thin-
layer channel from the working electrode. This results in a wide linear dynamic
range. The counterelectrode and a length of titanium inlet tubing at the inlet are
connected to ground (see Figure 2-4). This shunts minute electric currents that
might conduct from the pump through the flow stream into the working electrode.
The working electrode current is processed using low noise analog amplifiers and
filters. Additional digital filtering of the analog output is available.
Solvent Compatibility
The Dionex ED50A amperometry cell can be used with common reversed-phase
solvents such as methanol and acetonitrile. If a disposable working electrode on
Doc. 065551-01 6/13
Figure 2-4. Amperometry Cell (Cover removed)
2 • Description
Cell Inlet Tubing
Working
Electrode
Block
L) of the channel also allows
2-11
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