Chemistry Reference
In-Depth Information
Ta b le 1.2
Ions used in electrolytes, based on their good solubility in
different solvents
63-65
Ion type
Suitable solvent
H
+
Water, acetone, acetonitrile
Li
+
Acetone, acetonitrile
Na
+
Water, acetone, acetonitrile
K
+
Water, acetone, acetonitrile, DMF
Me
4
N
+
Acetone, acetonitrile, DMF, DMSO
Et
4
N
+
Acetone, acetonitrile, DMF, DMSO
Bu
4
N
+
Acetone, acetonitrile
Cl
-
Water, acetone, acetonitrile, DMF, DMSO
Br
-
Water, acetone, acetonitrile, DMF, DMSO
I
-
Water, acetone, acetonitrile, DMF, DMSO
NO
3
-
Water, acetone, acetonitrile, DMF, DMSO
BF
4
-
Acetonitrile
PF
6
-
Acetonitrile
ClO
4
-
Water, acetone, acetonitrile, DMF, DMSO
voltammetry that complexing a species to a more stable form results in
a more difficult reduction of this species (in other words higher nega-
tive overpotentials should be applied to reduce the species compared
with the non-complexed form). It can be useful that the supporting elec-
trolyte also acts as complexing agent.
Typical supporting electrolytes are given in Table 1.2, including the
environment
63-65
.
1.7
Charge-transfer and transport phenomena
1.7.1
Introduction
In order to develop an amperometric sensor, voltammetric research is
essential, both to find out about the working principle or mechanism of the
sensor reaction and to determine the appropriate working conditions
(amongst others, the potential of the working electrode). A potential in-line
sensor having an output signal which is continuously in proportion to the
concentration of the analyte can only be based on a time-independent
signal and hence on a voltammetric steady-state method making use of con-
figurations such as rotating disc electrodes, flow-through cells, ultramicro
electrodes, wall-jet electrodes or diffusion through membranes. For the
development of a sensor on a laboratory scale, predominately rotating-disc
voltammetry is used. In order to investigate the mechanism of the occur-
ring oxidation/reduction reactions, rotating-ring-disc voltammetry and non-
