Chemistry Reference
In-Depth Information
uric.acid.(UA)..Thanks.to.a.spontaneous.extractability.of.the.former.at.appropriately.chosen.condi-
tions.(i.e.,.by.keeping.Clp.in.the.form.of.neutral.and.uncharged.molecules),.the.analysis.could.be.
performed.in.a.sophisticated.way,.when.both.substances.were.preconcentrated.at.a.CPE;.Clp.being.
extracted. into. the. bulk,. whereas. UA. adsorbed. at. the. surface. only.. Then,. the. surface. layer. with.
accumulated.species.was.cut.off.and.UA.removed.as.such..Because.the.molecules.of.Clp.remained.
entrapped.in.the.carbon.paste.(see.also.Section.3.4.and.Figure.3.6),.this.drug.could.be.re-extracted.
out.of. CPE.and. subsequently. detected,.both.performable. during.the.voltammetric.scanning..The.
individual.sequences.can.then.be.formulated.as.follows:
.
1..
Accumulation
(
Clp
)
+
(
UA
)
→
(
Clp
)
+
(
UA
)
(8.5)
SOLN
SOLN
-
CP SURF
-
.
CP
BULK
.
.
2..
Surface removal and voltammetric detection
(
Clp
)
+
c UA
(
)
→
(
Clp
)
(8.6a)
-
CP SURF
-
SOLN
.
CP
BULK
.
(8.6b)
(
Clp
)
→
(
OxP
)
.
SOLN
SOLN
.
0.5 μA
0.5 μA
I
2
2
1
1
0
0
II
2 4
n
(replicates)
0
6 8
3 6
c.10
5
[mol L
-1
]
0
911
I
II
f
e
d
8
6
c
5
b
2
a
1
+0.3
(A)
+0.5
+0.7
+0.9
+1.1
+0.3
+0.5
+0.7
+0.9
+1.1
E
[V] vs. Ag/AgCl
E
[V] vs. Ag/AgCl
(B)
FIGURE 8.15
Anodic.oxidation.of.chlorpromazine.(Clp
*
).at.a.carbon.paste.electrode.in.highly.acidic.media..
(A).Typical.calibration.voltammograms:.(a).base-line.(s.e.),.(b-f).2-10.×.10
−5
.M.
Clp
;.(B).reproducibility.study:.
(1-8).eight.replicates..
Experimental conditions
:.CPE.made.of.highly.viscous.silicone.oil;.direct.DPV,.scan.rate:.
50.mV.·.s
−1
,.pulse.height:.−50.mV;.s.e.:.2.M.H
2
SO
4
.+.MeOH.[30.%.(w/w);.pH.∼.0].(*).
Chlorpromazine
,.antipsy-
chotic. agent;. 3-(2-chloro-10
H
-phenothiazinyl)-
N
,
N
-dimethyl-propan-1-amine. hydrochloride,. C
17
H
19
N
2
SCl..
(From.authors'.archives,.an.outtake.from.Švancara,.I..et.al.,.
Electrochim. Acta
,.37,.1355,.1992.)
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