Chemistry Reference
In-Depth Information
Ag
0
O
-
O
-
O
-
O
O
-
O
-
O
-
Ag
+
Ag
+
SO
3
-
SO
3
-
SO
3
-
Sample
solution
Ag
+
Ag
+
Ag
+
Ag
+
Original surface
of carbon paste
(˝C/TCP˝ type)
Altered surface
after activation
(cathodization)
Enhanced
electrolytic
accumulation
Additional ion-
pair formation
(with modiŒer)
Ag
100 nA
Concentration
[mol
.
L
-1
]
2.6 × 10
-12
2.0 × 10
-12
1.3 × 10
-12
6.7 × 10
-13
Base-line
-0.2
-0.1
0
+0.1
+0.2
+0.3
+0.4
E
[
V
] vs. SCE
FIGURE 3.5
Voltammetric. method. for. the. determination. of. Ag(I). at. tricresyl-phosphate-based. CPE:.
Scheme. of. its. synergistic. accumulation. mechanism. (upper. part). and. calibration. of. Ag(I). at. the. picomolar.
concentrations. (lower. part).. Base-line:. blank. supporting. electrolyte. (s.e.).
Experimental conditions
:. C/TCP.
electrode;.DPASV,.accumulation.conditions:.
E
ACC
.=.−0.2.V.vs..SCE,.
t
ACC
.=.120.min,.
t
EQ
.=.30.s;.stripping.limits:.
E
INIT
.=.−0.2.V,.
E
FIN
.=.+0.5.V.vs..ref.,.scan.rate:.20.mV.·.s
−1
;.s.e.:.0.02.M.acetate.buffer.+.8.×.10
−5
.M.
n
-C
7
H
15
-
SO
3
Na.+.0.003.M.EDTA;.each.sample.purged.for.5.min..(Assembled.and.redrawn.according.to.Švancara,.I..
et al.,.
Electroanalysis
,.8,.336,.1996.)
enable.the.simultaneous.analysis.of.two.[746].or.even.more.[747].optically.active.isomers..Finally,.
there.are.also.some.combinations.based.on.attracting.the.substance.of.interest.by.means.of.
immu-
noassay
. principles. (see,. e.g.,. [286,301-303]). with. the. subsequent. electrochemical. detection. that.
enables,. among. others,. to. analyze. even. some. microorganisms. like. bacteria. and. viruses. (see. also.
Chapter.8,.the.commentary,.and.table.survey).
3.4.2 i
nTeraCTions
in
C
arbon
p
asTe
b
ulk
CPEs. differ. from. other. solid. electrodes. by. the. presence. of. a. (usually). liquid. binder.. Thereby,.
most.processes.occurring.in.the.carbon.paste.interior.are.mainly.dependent.on.the.presence.and.
properties.of.the.liquid.binder..In.the.following.text,.one.considers.solely.the.process.at.traditional.
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