Biology Reference
In-Depth Information
expressed by [45]
Dc
b
t
d
l
δ
=
c
M
(8.3)
where
δ
is the width of the diffusion layer (dependent on the stirrer
speed or electrode rotation rate),
t
d
is the deposition time,
c
b
is the
bulkconcentrationofthemetalion,and
D
isitsdiffusioncoe
cient.
c
M
is related to the peak current
I
P
by [46]
n
2
F
2
ν
lAc
M
2
.
7
RT
=
I
P
(8.4)
where
v
is the scan rate,
A
is the film area,
R
is the gas constant,
and
T
is the temperature. The situation of a metal film on a screen-
printed electrode should approximate to the case of an extremely
thinmercuryfilm,andtherefore,Eq.(8.4)mayapproximatetheLSV
stripping response at such an electrode.
As shown in Fig. 8.7a, a drawback to LSV stripping can be
the rising baseline, which limits the technique's sensitivity. This
Figure 8.7.
ASV detection in sea water containing 30 ppb Cd, 75 ppb
Pb, and 65 ppb Cu at a HMDE using (a) linear sweep voltammetry and
(b) differential pulse voltammetry. Taken with permission from [133], W.
Lund and D. Onshus,
Anal. Chim. Acta
86
,109-122 (1976). c
Elsevier Ltd.
