Chemistry Reference
In-Depth Information
30
25
20
15
10
5
12
4
3
0
0
10
20
30
40
50
60
(a)
Z
¢
(kohm)
77
4.77
4
67
4.72
57
3
47
4.67
2
37
4.62
27
1
17
4.57
7
-3
4.52
-1.3
-0.3
0.7
1.7
2.7
3.7
4.7
5.7
(b)
Log
f
(Hz)
12.1
(a) Nyquist and (b) Bode plots recorded in styrene containing (1)
1.43
¥
10
-
4
, (2) 1.32
¥
10
-
4
, (3) 1.21
¥
10
-
4
and (4) 1.10
¥
10
-
4
mol l
-
1
THAP using a platinum conductivity cell with K
=
1 at 298.0 K.
(Reprinted from
Microchemical Journal
, Vol 77, De Wael et al,
'Electrochemical detection . . .', pp 85-92 (2004), with permission
from Elsevier.)
between applied potential and measured current is observed. Despite the
decrease of the resistance, it remains very high (40-60 kohm) compared
with aqueous solutions where typical values for
R
with electrolyte concen-
trations of 1 ¥ 10
-2
mol l
-1
are a few hundreds of an ohm. This is about 200
times less than the resistance obtained in styrene solutions containing
THAP, and the effect can be explained by the very low dielectricity con-
stant (e=2.43 at 298.0 K) compared with water (e=78 at 298.0 K), which
