Biology Reference
In-Depth Information
for the same potential range and the data are not influenced by the
current offset. One scan rate is taken as a reference, while more
scan rates are chosen as selected multiples of the reference scan
rate.
For elimination procedure, two necessary assumptions must be
fulfilled:
1. The total current resulting from different individual processes
such as diffusion, adsorption, and kinetics is formed by the sum
ofthese particular currents:
I
=
I
d
+
I
c
+
I
k
,
where
I
d
,
I
c
,and
I
k
are the diffusion, charging, and kinetic
currents, respectively.
2. The particular currents eliminated are expressed as the product
oftwo independent functions:
=
Y
j
(
E
)
W
j
(
ν
)
,
I
j
where
Y
j
(
E
)istheelectrodepotentialfunctionand
W
j
(
ν
)isthe
scan rate function.
The scan rate function has the form of a certain power of
x
of the
scan rate. For example, for a substance transported to an electrode
only by diffusion, the rate power coe
cient of
1
/
2
corresponds to
the diffusion current
I
d
, while
x
=
1 or 0 holds for the charging
current
I
c
,orthekineticcurrent
I
k
,respectively[5-7,21].According
to the second condition of the elimination procedure, the particular
currents take the form
Y
d
(
E
)
v
1
/
2
Y
k
(
E
)
v
0
Y
c
(
E
)
v
1
I
d
=
,
I
k
=
,
and
I
c
=
,
where
Y
j
(
E
) of the individual current characterizes a proportion-
ality which is independent of scan rate at the selected potential
value. It has been proved that for the elimination function
f
(
I
)in
addition to the total current at a reference scan rate
I
, the total
currents for half and double of its value,
I
1
/
2
and
I
2
, are suitable
[5, 7, 13, 21]. EVLS functions have been used for the different
combinationswiththesamescanrateratio(integer2)formorethan
13 years. The types of six elimination functions are presented in
Table 11.1.
