Comunicacion oral eseac_2010 [modo de compatibilidad]
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Transcript of Comunicacion oral eseac_2010 [modo de compatibilidad]
DIFFERENTIAL POTENTIOMETRY AND DIFFERENTIAL POTENTIOMETRY AND
DIFFERENTIAL DYNAMIC RESPONSE WITH IONDIFFERENTIAL DYNAMIC RESPONSE WITH ION
SELECTIVE ELECTRODES: APPLICATION TO SELECTIVE ELECTRODES: APPLICATION TO
CYCLODEXTRINECYCLODEXTRINE--BASED DRUG SELECTIVEBASED DRUG SELECTIVE
ELECTRODESELECTRODESELECTRODESELECTRODES
María CuarteroMaría Cuartero , Joaquín A. Ortuño and MªSoledad García
MÉTODOS AUTOMÁTICOS DE ANÁLISIS. SENSORES QUÍMICOS
“AUTOMATIC METHODS OF ANALYSIS. CHEMICAL SENSORS”
Department of Analytical Chemistry. Faculty of Chemistry
University of Murcia. Murcia. Spain
IONION--SELECTIVE ELECTRODESSELECTIVE ELECTRODES
ISEsISEsSelectivity
Sensitivity
Simplicity Rapid response
Longterm
Wide linear range
Low cost
Applications
PLASTICIZED POLYMERIC MEMBRANES
Longterm stability
Low cost
PVCPlasticizer
Ionic additiveIonophore
The appropriate selection of the components enables the selectivity of the ISE to be controlled.
Dynamic response Dynamic response studiesstudies
Response time of the sensor
Working mechanism
Practical applications
important
(E vs t)
Interfering ions
Data matrix (E and t)
Qualitative and quantitative purposes
particulary relevant
exploited
SOFTWARETWO-ELECTRODE POTENTIOMETRY
electrode 1
reference electrode
electrode 2
ELECTRODE 1
ELECTRODE 2
REFERENCE ELECTRODE
High impedance buffers
Analogmultiplexer
A/D converter16 bits+
-
Reference voltage2.5 V
Digital control
Controller
USB interface
PC
ELECTRODE 1
ELECTRODE 2
REFERENCE ELECTRODE
High impedance buffers
Analogmultiplexer
A/D converter16 bits+
-
Reference voltage2.5 V
Digital control
Controller
USB interface
PC
The potential difference between twoISEs are alternatively measured bymeans of two analog circuits, a fastmultiplexer and an analog-to digitalconverter. The potential differencebetween both ISEs is obtained bydigital substraction of the previousrecording.
This procedure has the advantage thatnot only is the potential differencebetween two ISEs monitored but alsothe potential of each electode.
TwoTwo--electrode potentiometryelectrode potentiometry
TwoTwo--electrode potentiometryelectrode potentiometry
TwoTwo--electrode potentiometryelectrode potentiometry
Electrode 1
Electrode 2
TwoTwo--electrode potentiometryelectrode potentiometry
Electrode 1
Electrode 2
DIFFERENTIAL DYNAMIC RESPONSE (DDR)DIFFERENTIAL DYNAMIC RESPONSE (DDR)
TwoTwo--electrodes potentiometryelectrodes potentiometry
Electrode 1
Electrode 2
DIFFERENTIAL DYNAMIC RESPONSE (DDR)DIFFERENTIAL DYNAMIC RESPONSE (DDR)
DIFFERENTIAL DIFFERENTIAL POTENTIOMETRY (DP)POTENTIOMETRY (DP)
The potential difference between both electrodes once that the steady-state value has
been attained
Overall potential response
E (∆Go, βCD-drug , …)
The direct transfer of the ionic drug from water to
the plasticizer is favourable.
Formation constant of complexes between CD and drug are not very
high.
OR''
O
H
ORH
O
n
R'O
n=6 � α-CD
n=7 � β-CD
n=8 � γ-CD
alkylated cyclodextrin-based drug selective electrodes
Overall potential response
E (∆Go, βCD-drug , …)
The direct transfer of the ionic drug from water to
the plasticizer is favourable.
Formation constant of complexes between CD and drug are not very
high.
benzoyl beta-cyclodextrin derivative
Overall potential response
E (∆Go, βCD-drug , …)
The direct transfer water-plasticizer is very favourable
Not very high
benzoyl beta-cyclodextrin derivative
AntiarrhytmicAntiarrhytmic
N
N
O
HO
H
H
H2N
O
N
Procainamide
Quinidine
AntimalarialAntimalarial
N
N
HO
O
H
H
Quinine
AntidepressantAntidepressant
N
N
Clomipramine
AnesthesicsAnesthesics
Overall potential response
E (∆Go, βCD-drug , …)
The direct transfer water-plasticizer is very favourable
Not very high
benzoyl beta-cyclodextrin derivative
AnesthesicsAnesthesics
HN
N
O
BupivacaineHN N
O
Lidocaine
H2N
O
N
O
Procaine
NH
O
N
O
TetracaineN
O
O
O
O
Papaverine
AntispasmodicAntispasmodic
AnesthesicsAnesthesics
Lidocaine
benzoyl beta-cyclodextrin derivative
Overall potential response
E (∆Go, βCD-drug , …)
The direct transfer water-plasticizer is very favourable
Not very high
HN
N
O
BupivacaineHN N
O
Lidocaine
H2N
O
N
O
Procaine
NH
O
N
O
TetracaineN
O
O
O
O
Papaverine
AntispasmodicAntispasmodic
lipophilic aromatic ring system and a nitrogen that can be protonated to provide
a cationic drug
Overall potential response
E (∆Go, βCD-drug , βCD-plasticizer …)
The direct transfer water-plasticizer is very favourable
Not very high
Neutral, lipophilic CDs manifest recognition by three types of interactions:
� conventional hydrophobic bonding
� -N-H…O and N-C-H…O hydrogen bonding
� van der Waals’ forces.
AnesthesicsAnesthesics
Lidocaine
benzoyl beta-cyclodextrin derivative
HN
N
O
BupivacaineHN N
O
Lidocaine
H2N
O
N
O
Procaine
NH
O
N
O
TetracaineN
O
O
O
O
Papaverine
AntispasmodicAntispasmodic
lipophilic aromatic ring system and a nitrogen that can be protonated to provide
a cationic drug
Overall potential response
E (∆Go, βCD-drug , βCD-plasticizer …)
The direct transfer water-plasticizer is very favourable
Not very high
Neutral, lipophilic CDs manifest recognition by three types of interactions:
� conventional hydrophobic bonding
� -N-H…O and N-C-H…O hydrogen bonding
� van der Waals’ forces.
benzoyl beta-cyclodextrin derivative
ELECTRODE 1ELECTRODE 1
MembraneMembrane:
100 mg Polyvinyl chloride (PVCPVC) 30%30%
200 mg PlasticizerPlasticizer 60%60%
30 mg Heptakis(2,3,5-tri-O-benzoyl)-β-cyclodextrin (ββ--CDCD) 9%9%
3 mg tetrakis[3,5-bis-(trifluoromethyl)phenyl]borate (TFMPBTFMPB) 1%1%
ELECTRODE 2ELECTRODE 2
Blank Membrane:Blank Membrane:
100 mg PVCPVC 33%33%
200 mg PlasticizerPlasticizer 66%66%
3 mg TFMPBTFMPB 1%1%
MEMBRANES ASSAYEDMembranes DOS NPOE TCP FNDPE PVC TFMB Β-CD
A - - - 66 33 1 -
B - - - 60 30 1 9
C - - 66 - 33 1 -
D - - 60 - 30 1 9
E - 66 - - 33 1 -
F - 60 - - 30 1 9
G 66 - - - 33 1 -
H 60 - - - 30 1 9
dioctyl sebacate (DOS), 2-nitrophenyl octyl ether (NPOE), tricresyl phosphate (TCP), 2-fluoro-2’-nitrodiphenyl ether (FNDPE), polyvinyl chloride (PVC) , potassium tetrakis[3,5-bis-(trifluoromethyl)phenyl]borate (TFMB) and
Heptakis(2,3,5-tri-O-benzoyl)-β-cyclodextrin (β-CD)
MEMBRANES ASSAYEDMembranes DOS NPOE TCP FNDPE PVC TFMB Β-CD
A - - - 66 33 1 -
B - - - 60 30 1 9
C - - 66 - 33 1 -
D - - 60 - 30 1 9
E - 66 - - 33 1 -
F - 60 - - 30 1 9
G 66 - - - 33 1 -
H 60 - - - 30 1 9
dioctyl sebacate (DOS), 2-nitrophenyl octyl ether (NPOE), tricresyl phosphate (TCP), 2-fluoro-2’-nitrodiphenyl ether (FNDPE), polyvinyl chloride (PVC) , potassium tetrakis[3,5-bis-(trifluoromethyl)phenyl]borate (TFMB) and
Heptakis(2,3,5-tri-O-benzoyl)-β-cyclodextrin (β-CD)
H2O
Ag-AgCl │KCl (1x10 -4 M)│internal solution, 1x10 -4 M KCl│PVC membrane │sample solution
Reproducible initial stage The electrodes were conditioned in deionized
water until they reached a constant potential
MEMBRANES ASSAYEDMembranes DOS NPOE TCP FNDPE PVC TFMB Β-CD
A - - - 66 33 1 -
B - - - 60 30 1 9
C - - 66 - 33 1 -
D - - 60 - 30 1 9
E - 66 - - 33 1 -
F - 60 - - 30 1 9
G 66 - - - 33 1 -
H 60 - - - 30 1 9
dioctyl sebacate (DOS), 2-nitrophenyl octyl ether (NPOE), tricresyl phosphate (TCP), 2-fluoro-2’-nitrodiphenyl ether (FNDPE), polyvinyl chloride (PVC) , potassium tetrakis[3,5-bis-(trifluoromethyl)phenyl]borate (TFMB) and
Heptakis(2,3,5-tri-O-benzoyl)-β-cyclodextrin (β-CD)
Ag-AgCl │KCl (1x10 -4 M)│internal solution, 1x10 -4 M KCl│PVC membrane │sample solution
Reproducible initial stageA flux of potassium ions from the inner solution
to the sample solution is established until a steady-state concentration profile inside the
membrane is reached, which is manifested as a CONSTANT ELECTRODE POTENTIALCONSTANT ELECTRODE POTENTIAL
Concentration perturbation (Input)Concentration perturbation (Input)
Standard addition methodStandard addition method
Adding consecutive volumes of concentrated solution of the
different drugs
Concentration perturbation (Input)Concentration perturbation (Input)
log C
time
Concentration perturbation (Input)Concentration perturbation (Input)
log C
time
Concentration perturbation (Input)Concentration perturbation (Input)
log C
time
The duration of each step depended on the electrode response observed and, in general, decreased as the
concentration was increased.
SAMPLE SOLUTION
ION-SELECTIVE MEBRANE INTERNAL SOLUTION
δaq δm
[CD-K]
aJ(bulk)
CONCENTRATION PROFILESCONCENTRATION PROFILES
aK
[CD-J]
aDaK(bulk)
K= potassium
J= ionic drug
CD= cyclodextrin
δ= diffusion layer
during exposure to the corresponding ionic drug, a flux towards the filling solution is established, couple d to a
flux of potassium in the opposite direction
MEMBRANEMEMBRANE INTERNAL SOLUTION INTERNAL SOLUTION SAMPLE SOLUTIONSAMPLE SOLUTION
K+
K+
K+
K+
J+
J+
J+
J+ J+ J+
CD
K
K+
K+
KCl 10KCl 10 --44 MM
K+
K+
J+
J+
J+
J+
K+K+
t / s
0 1000 2000 3000 4000
E1-
E2
/ mV
0
50
100
150
200
250
t / s0 1000 2000 3000
E1-
E2
/ mV
0
10
20
30
40
50
60
DOS TCP
1
2
3
4
56
7 8
1
2
3
45 6 87
DDR of lidocaine (different plasticizers)DDR of lidocaine (different plasticizers)
t / s0 500 1000 1500 2000
E1-
E2
/ mV
-50
0
50
100
150
200
250
t / s0 200 400 600 800 1000 1200 1400 1600 1800
E1-
E2
/ mV
-50
0
50
100
150
200
250
NPOE FNDPE
12
3
4
5
68
1 2
3
4
56
87
7
(1) 0 M, (2) 1x10-6 M, (3) 5x10-6 M, (4) 1x10-5 M, (5) 5x10-5 M, (6) 1x10-4 M, (7) 5x10-4 M, (8) 1x10-3 M
t / s
0 1000 2000 3000 4000
E1-E
2 /
mV
0
50
100
150
200
250
t / s0 1000 2000 3000
E1-E
2 / m
V
0
10
20
30
40
50
60
200
250
200
250
DOS TCP
NPOE FNDPE
1
2
3
4
56
7 8
4
1
2
3
45 6 8
4
7
t / s
0 1000 2000 3000 4000
E1-E
2 /
mV
0
50
100
150
200
250
t / s0 1000 2000 3000
E1-E
2 / m
V
0
10
20
30
40
50
60
200
250
200
250
DOS TCP
NPOE FNDPE
1
2
3
4
56
7 8
4
1
2
3
45 6 8
4
7
DDR of lidocaine (different plasticizers)DDR of lidocaine (different plasticizers)
The lidocaine concentration at which this inversion occured
depend on the plasticizer used. For
DOS, NPOE and FNDPE increased with the dielectric constant
(ε=4, 24 and 50 respectively).
t / s0 500 1000 1500 2000
E1-E
2 / m
V
-50
0
50
100
150
t / s0 200 400 600 800 1000 1200 1400 1600 1800
E1-E
2 / m
V
-50
0
50
100
150
12
3
5
68
1 2
3
56
87
7
(1) 0 M, (2) 1x10-6 M, (3) 5x10-6 M, (4) 1x10-5 M, (5) 5x10-5 M, (6) 1x10-4 M, (7) 5x10-4 M, (8) 1x10-3 M
t / s0 500 1000 1500 2000
E1-E
2 / m
V
-50
0
50
100
150
t / s0 200 400 600 800 1000 1200 1400 1600 1800
E1-E
2 / m
V
-50
0
50
100
150
12
3
5
68
1 2
3
56
87
7
(1) 0 M, (2) 1x10-6 M, (3) 5x10-6 M, (4) 1x10-5 M, (5) 5x10-5 M, (6) 1x10-4 M, (7) 5x10-4 M, (8) 1x10-3 M
respectively).
The potential corresponding to the
inversion was roughly the same for these three plasticizers.
t / s
0 1000 2000 3000 4000
E1-E
2 /
mV
0
50
100
150
200
250
t / s0 1000 2000 3000
E1-E
2 / m
V
0
10
20
30
40
50
60
200
250
200
250
DOS TCP
NPOE FNDPE
1
2
3
4
56
7 8
4
1
2
3
45 6 8
4
7
t / s
0 1000 2000 3000 4000
E1-E
2 /
mV
0
50
100
150
200
250
t / s0 1000 2000 3000
E1-E
2 / m
V
0
10
20
30
40
50
60
200
250
200
250
DOS TCP
NPOE FNDPE
1
2
3
4
56
7 8
4
1
2
3
45 6 8
4
7
DDR of lidocaine (different plasticizers)DDR of lidocaine (different plasticizers)
One drawback of the membranes
constructed with DOS, NPOE and FNDPE, is that the response is
not reproducible because the membrane can not be regenerated after a concentration
perturbation.
t / s0 500 1000 1500 2000
E1-E
2 / m
V
-50
0
50
100
150
t / s0 200 400 600 800 1000 1200 1400 1600 1800
E1-E
2 / m
V
-50
0
50
100
150
12
3
5
68
1 2
3
56
87
7
(1) 0 M, (2) 1x10-6 M, (3) 5x10-6 M, (4) 1x10-5 M, (5) 5x10-5 M, (6) 1x10-4 M, (7) 5x10-4 M, (8) 1x10-3 M
t / s0 500 1000 1500 2000
E1-E
2 / m
V
-50
0
50
100
150
t / s0 200 400 600 800 1000 1200 1400 1600 1800
E1-E
2 / m
V
-50
0
50
100
150
12
3
5
68
1 2
3
56
87
7
(1) 0 M, (2) 1x10-6 M, (3) 5x10-6 M, (4) 1x10-5 M, (5) 5x10-5 M, (6) 1x10-4 M, (7) 5x10-4 M, (8) 1x10-3 M
perturbation.
DOS, NPOE and FNDPE ���� none reproducible
TCP ���� reproducible
t / s
0 1000 2000 3000 4000
E1-E
2 /
mV
0
50
100
150
200
250
t / s0 1000 2000 3000
E1-E
2 / m
V
0
10
20
30
40
50
60
200
250
200
250
DOS TCP
NPOE FNDPE
1
2
3
4
56
7 8
4
1
2
3
45 6 8
4
7
t / s
0 1000 2000 3000 4000
E1-E
2 /
mV
0
50
100
150
200
250
t / s0 1000 2000 3000
E1-E
2 / m
V
0
10
20
30
40
50
60
200
250
200
250
DOS TCP
NPOE FNDPE
1
2
3
4
56
7 8
4
1
2
3
45 6 8
4
7
DDR of lidocaine (different plasticizers)DDR of lidocaine (different plasticizers)
In contrast, the membrane constructed with TCP displayed a much lower potential
respose but its response was reproducible.
The different behaviour displayed by TCP can
t / s0 500 1000 1500 2000
E1-E
2 / m
V
-50
0
50
100
150
t / s0 200 400 600 800 1000 1200 1400 1600 1800
E1-E
2 / m
V
-50
0
50
100
150
12
3
5
68
1 2
3
56
87
7
(1) 0 M, (2) 1x10-6 M, (3) 5x10-6 M, (4) 1x10-5 M, (5) 5x10-5 M, (6) 1x10-4 M, (7) 5x10-4 M, (8) 1x10-3 M
t / s0 500 1000 1500 2000
E1-E
2 / m
V
-50
0
50
100
150
t / s0 200 400 600 800 1000 1200 1400 1600 1800
E1-E
2 / m
V
-50
0
50
100
150
12
3
5
68
1 2
3
56
87
7
(1) 0 M, (2) 1x10-6 M, (3) 5x10-6 M, (4) 1x10-5 M, (5) 5x10-5 M, (6) 1x10-4 M, (7) 5x10-4 M, (8) 1x10-3 M
displayed by TCP can be explained from
some results reported in the literature that
point to an interaction between TCP and
protonated amines.
DOS, NPOE and FNDPE ���� none reproducible
TCP ���� reproducible
DP of lidocaine (different plasticizers)DP of lidocaine (different plasticizers)
150
200
250
Plots of DP versus logarithmic concentration of lidocaine
The response of the electrode containing CD is higher than the response
log [L] / M
-6 -5 -4 -3
mV
-50
0
50
100
150DOS TCP NPOE FNDPE
higher than the response of the electrode without CD at low concentration,
while the response is more similar at higher
concentrations.
t / s0 1000 2000 3000
E1-
E2
/ mV
0
10
20
30
40
50
60
t / s
0 1000 2000 3000 4000
E1-
E2
/ mV
-20
-10
0
10
20
30
40
DDR of different ionic drugs (membranes with TCP)DDR of different ionic drugs (membranes with TCP)
LIDOCAINEPROCAINE
81
2
3
4
576
1
2
3
46 85 7
t / s
0 1000 2000 3000
E1-
E2
/ mV
0
20
40
60
80
100
t / s
0 500 1000 1500 2000 2500 3000
E1-
E2
/ mV
0
10
20
30
40
50
60
t / s
(1) 0 M, (2) 1x10-6 M, (3) 5x10-6 M, (4) 1x10-5 M, (5) 5x10-5 M, (6) 1x10-4 M, (7) 5x10-4 M, (8) 1x10-3 M
CLORMIPRAMINEPAPAVERINE
81
2
34
5 6 78
1
2
34
657
t / s0 1000 2000 3000
E1-
E2
/ mV
0
10
20
30
40
50
60
80
100
50
60
t / s
0 1000 2000 3000 4000
E1-
E2
/ mV
-20
-10
0
10
20
30
40
LIDOCAINE
CLORMIPRAMINEPAPAVERINE
PROCAINE
2
81
2
3
4
576
1
2
3
46 85 7
t / s0 1000 2000 3000
E1-
E2
/ mV
0
10
20
30
40
50
60
80
100
50
60
t / s
0 1000 2000 3000 4000
E1-
E2
/ mV
-20
-10
0
10
20
30
40
t / s0 1000 2000 3000
E1-
E2
/ mV
0
10
20
30
40
50
60
80
100
50
60
t / s
0 1000 2000 3000 4000
E1-
E2
/ mV
-20
-10
0
10
20
30
40
LIDOCAINE
CLORMIPRAMINEPAPAVERINE
PROCAINE
2
81
2
3
4
576
1
2
3
46 85 7
DDR of different ionic drugs (membranes with TCP)DDR of different ionic drugs (membranes with TCP)
t / s
0 1000 2000 3000
E1-
E2
/ mV
0
20
40
60
t / s
0 500 1000 1500 2000 2500 3000
E1-
E2
/ mV
0
10
20
30
40
(1) 0 M, (2) 1x10-6 M, (3) 5x10-6 M, (4) 1x10-5 M, (5) 5x10-5 M, (6) 1x10-4 M, (7) 5x10-4 M, (8) 1x10-3 M
CLORMIPRAMINE
81
34
5 6 78
1
2
34
657
t / s
0 1000 2000 3000
E1-
E2
/ mV
0
20
40
60
t / s
0 500 1000 1500 2000 2500 3000
E1-
E2
/ mV
0
10
20
30
40
t / s
0 1000 2000 3000
E1-
E2
/ mV
0
20
40
60
t / s
0 500 1000 1500 2000 2500 3000
E1-
E2
/ mV
0
10
20
30
40
(1) 0 M, (2) 1x10-6 M, (3) 5x10-6 M, (4) 1x10-5 M, (5) 5x10-5 M, (6) 1x10-4 M, (7) 5x10-4 M, (8) 1x10-3 M
CLORMIPRAMINE
81
34
5 6 78
1
2
34
657
The more lipophilic the ionic drug (clomipramine>papaverine>lidocaine>procaine), the l ower the inversion
concentration and the higher the inversion potentia l
t / s0 1000 2000 3000
E1-
E2
/ mV
0
10
20
30
40
50
60
80
100
50
60
t / s
0 1000 2000 3000 4000
E1-
E2
/ mV
-20
-10
0
10
20
30
40
LIDOCAINE
CLORMIPRAMINEPAPAVERINE
PROCAINE
2
81
2
3
4
576
1
2
3
46 85 7
t / s0 1000 2000 3000
E1-
E2
/ mV
0
10
20
30
40
50
60
80
100
50
60
t / s
0 1000 2000 3000 4000
E1-
E2
/ mV
-20
-10
0
10
20
30
40
t / s0 1000 2000 3000
E1-
E2
/ mV
0
10
20
30
40
50
60
80
100
50
60
t / s
0 1000 2000 3000 4000
E1-
E2
/ mV
-20
-10
0
10
20
30
40
LIDOCAINE
CLORMIPRAMINEPAPAVERINE
PROCAINE
2
81
2
3
4
576
1
2
3
46 85 7
DDR of different ionic drugs (membranes with TCP)DDR of different ionic drugs (membranes with TCP)
t / s
0 1000 2000 3000
E1-
E2
/ mV
0
20
40
60
t / s
0 500 1000 1500 2000 2500 3000
E1-
E2
/ mV
0
10
20
30
40
(1) 0 M, (2) 1x10-6 M, (3) 5x10-6 M, (4) 1x10-5 M, (5) 5x10-5 M, (6) 1x10-4 M, (7) 5x10-4 M, (8) 1x10-3 M
CLORMIPRAMINE
81
34
5 6 78
1
2
34
657
t / s
0 1000 2000 3000
E1-
E2
/ mV
0
20
40
60
t / s
0 500 1000 1500 2000 2500 3000
E1-
E2
/ mV
0
10
20
30
40
t / s
0 1000 2000 3000
E1-
E2
/ mV
0
20
40
60
t / s
0 500 1000 1500 2000 2500 3000
E1-
E2
/ mV
0
10
20
30
40
(1) 0 M, (2) 1x10-6 M, (3) 5x10-6 M, (4) 1x10-5 M, (5) 5x10-5 M, (6) 1x10-4 M, (7) 5x10-4 M, (8) 1x10-3 M
CLORMIPRAMINE
81
34
5 6 78
1
2
34
657
The different DDR obtained for all the drugs assaye d could well be used for qualitative purposes
DP (membranes with TCP)DP (membranes with TCP)
60
80Na+ K+
Mg2+ Ca2+ NH
4+
TEA
Plots of DP versus logarithmic concentration of the different compounds assayed
log [C] / M
-10 -8 -6 -4 -2
mV
0
20
40
TEA ProcainamideProcaineLidocaineTetracaineBupivacaineQuinidinaQuininaPapaverineClormipramine
Perturbation of concentrationPerturbation of concentrationConcentration perturbation (Input)Concentration perturbation (Input)
log C
The electrode is re-conditioned in deionised
water after each concentration perturbation
time
Concentration perturbation (Input)Concentration perturbation (Input)
log C
The electrode is re-conditioned in deionised
water after each concentration perturbation
time
E1-
E2
/ mV
(1d
iv=5
mV
)
DDR of lidocaine (membranes with TCP)DDR of lidocaine (membranes with TCP)
1x10-6 M 5x10-6 M 1x10-5 M
t / s (1div=50 s)
E1-
E2
/ mV
(1d
iv=2
0mV
)
t / s (1div=20 s)
E1-
E2
/ mV
(1d
iv=2
0mV
)
5x10-5 M 1x10-4 M 5x10-4 M
log C mV
DDR of lidocaine (membranes with TCP)DDR of lidocaine (membranes with TCP)
time time
CONCENTRATION PERTURBATION
(INPUT=MONOTONIC)DDR
(OUTPUT=NON-MONOTONIC)
This type of signals has been reported for the dyna mic response of several types of ISEs in the presence of interfiring ions.
mV 150
200
250
300
5x10-4 M
1x10-4 M
5x10-5 M
electrode 1
electrode 2 (Blank membrane)m
V 150
200
250
300
5x10-4 M
1x10-4 M
5x10-5 M
electrode 1
electrode 2 (Blank membrane)
electrode 1
electrode 2 (Blank membrane)
DDR of lidocaine (membranes with TCP)DDR of lidocaine (membranes with TCP)
t / s (1div=50 s)
E1-
E2
/ mV
(1d
iv=5
mV
) 1x10-6 M 5x10-6 M 1x10-5 M
t / s (1div=50 s)
E1-
E2
/ mV
(1d
iv=5
mV
) 1x10-6 M 5x10-6 M 1x10-5 M
t / s
0 200 400 600 800 1000 1200 1400 1600
mV
0
50
100
1x10-5 M
5x10-6 M
1x10-6 M
t / s
0 200 400 600 800 1000 1200 1400 1600
mV
0
50
100
1x10-5 M
5x10-6 M
1x10-6 M
E1-
E2
/ mV
(1d
iv=2
0mV
)
t / s (1div=20 s)
E1-
E2
/ mV
(1d
iv=2
0mV
)
5x10-5 M 1x10-4 M 5x10-4 M
E1-
E2
/ mV
(1d
iv=2
0mV
)
t / s (1div=20 s)
E1-
E2
/ mV
(1d
iv=2
0mV
)
5x10-5 M 1x10-4 M 5x10-4 M
DDR(NON-MONOTONIC)
DR(MONOTONIC)
150
200
250
Calibration graphs for DP and DDR of lidocaine (mem branes Calibration graphs for DP and DDR of lidocaine (mem branes with TCP)with TCP)
A
BDDR
log [L] / M
-6 -5 -4 -3
mV
-50
0
50
100
E(mV)=724.84+151.44log[L(M)+1.06x10-5]
A
│A│-│B│
CONVENTIONAL DP
rather odd signals
two ionic drug trasport inside the membrane
free ionic drug complexed ionic drug
the difussion of CD to the sample interface is insufficient to complex all the ionic drug arising from the
sample solution
lower concentrations higher concentrations
CONCLUSIONSCONCLUSIONS
I. The new differential dynamic response technique,applied to ion-selective electrodes, and exploited herefor the first time, is a source of signals not usuallyseen that can be useful for quantitative an qualitativeanalysis.
II. When the DDR is applied to ISEs based on a β-cyclodextrin, the ionic drugs assayed seem to betransported across the membrane following twodifferent processes.
THANK YOU FOR YOUR ATTENTIONTHANK YOU FOR YOUR ATTENTION