RADIOMETER ABL800 FLEX, Reference Manual

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2. Amperometric measuring principles ABL800 FLEX Reference Manual
General information
Amperometric
method The magnitude of an electrical current flowing through an electrode chain, which
is in turn proportional to the concentration of the substance being oxidized or
reduced at an electrode in the chain
The electrode chain in amperometric measurements consists of the sample, the two
electrodes (anode and cathode), an amperemeter, a voltage source, the membranes,
and the electrolyte solutions.
Amperemeter
Applied voltage
Anode Cathode
Electrolyte solution
Membrane
Sample
Part Function
Cathode Negative electrode where a reduction reaction occurs and
electrons are consumed.
Anode Positive electrode where an oxidation reaction occurs and
electrons are released.
Electrolyte
solution Provides electrical contact between the anode and cathode.
Membrane Allows the appropriate molecules to pass through from the
sample.
Sample Contacts the membrane.
Applied voltage Applies the necessary potential for the reduction or oxidation
reaction under study.
Amperemeter Measures the current flowing through the circuit.
To simplify the description of the measuring process in an amperometric electrode,
we make the following assumptions:
•
there is a species A in the sample which is reduced at the cathode to A
−
.
•
there is a species X in the electrolyte which is oxidized at the anode to X
+
.
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