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70 211_0010 - ROXY Exceed user manual - rev 04
Electrochemical reactions
In an electrochemical reactor a reaction of the analyte at an electrode sur-
face occurs. For electrochemically active compounds, the potential be-
tween reference electrode (REF) and working electrode (WE) determines
the reactivity of the analyte at the WE. The potential difference supplies
the energy level needed to initiate or enhance the electrochemical reac-
tion. Different analytes may have different oxidation or reduction potentials.
Fig. 26. Oxidation/reduction reaction of norepinephrine.
An example of an electrochemical reaction is shown in Fig. 26, norepi-
nephrine is converted into a quinone by oxidation at the WE. Two elec-
trons are transferred at the WE resulting in an electrical current that is am-
plified by the controller.
The mechanism of the REDOX reactions is the same for the ROXY appli-
cations. The potential is the reactions driving force, but the mass spec-
trometry (MS) is applied for the oxidation or reduction products detection.
An example of an electrochemical reaction is shown in Fig. 26, norepi-
nephrine is converted into a quinone by oxidation at the WE. Two elec-
trons are transferred at the WE resulting in an electrical current that is am-
plified by the controller. The norepinephrine and its quinone product itself
will be detected in mass spectrometer in ROXY applications.
Because of the same nature of electrochemical reactions in electro-
chemical detection and ROXY applications with MS detection some
details that are strictly related to the electrochemical detection are
presented in the following paragraphs. The purpose of these frag-
ments is to explain the processes occurring in the electrochemical
cell.