Studies on N-alkylatedPolyaniline and its

application to measurementof hydrogen peroxyde at

neutral pHDiego L. Raffa1, K. Tong Leung2, Fernando Battaglini1

1 Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires2 Department of Chemistry, University of Waterloo

Redox and Acid-Base Equilibria of Polyaniline

NH

NH

NH

NH

N

N N

N

NH

NH

N

N

NH

NH

N+

H

N+

H

A-

A-

2A- -2e -2A- -2e

2A- +2H+

Insulating

Insulating

Conducting

How to use it in Sensors

i

time

C4C3C2C1

C1<C2<C3<C4

GOxPoly(o-phenylendiamine)

PANI

Carbon Electrodes

HRP

V

POLYMER

CARBON BAND

INSULATOR

Examples

P. N. Bartlett y P. R. Birkin; Synthetic Metals, 61 (1993) 15-21 P. N. Bartlett; P. R. Birkin; J.H Wang; F. Palmisano; G. De

Benedetto; Anal.Chem. 1998, 70, 3685-3694.

Attempt to improve the problem of pH

•Polymerization in presence of PSS orPVS•A Donnan potential that keeps positiveions in the film is created

Results:•The polymer conductivity is temporarily improved at pHs between 6 and 7•After some minutes, conductivity decreases and is only recovered by immersion in acid

Our Attempt: Sultonation

NH

NH

NH

NH

n

¨¨

¨¨

OS

OO

+

NH

NH

NH

n

N

SO3-

XPS Analysisx 102

50

60

70

80

90

100

CPS

410 408 406 404 402 400 398 396 394 392 390Binding Energy (eV)

x 102

40

50

60

70

80

90

CPS

410 408 406 404 402 400 398 396 394 392 390Binding Energy (eV)

Before After

N1S

190

200

210

220

CPS

N1S

160

165

170

CPS

N1S.DTS

x 102

160

170

180

406 404 402 400 398 396 394Binding Energy (eV)

N1S.DTS

x 102

150

155

406 404 402 400 398 396 394Binding Energy (eV)

3 hs room T overnight room TN1S.DTS

N1S

x 102

140

145

150

155

160

165

170

175

180

185

CPS

406 404 402 400 398 396 394Binding Energy (eV)

N1S.DTS

N1S

x 102

160

165

170

175

180

185

190

195

CPS

406 404 402 400 398 396 394Binding Energy (eV)

3 hs 60ºC overnight 60ºC

Electrochemistry results

-70

-50

-30

-10

10

30

50

70

90

110

-0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50E vs Ag|AgCl/V

i/A

H2SO4 1,8 M, 50 mVs-1

Electrochemistry results

-70-60-50-40-30-20-10

0102030405060

-0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50E vs Ag|AgCl/V

i/A

Buffer acetic 0,1 M; pH 4,7; 50 mVs-1

Electrochemistry results

-8-7-6-5-4-3-2-1012345678

-0.20 -0.10 0.00 0.10 0.20 0.30 0.40 0.50E vs Ag|AgCl/V

i/A

Buffer PIPES 50 mM; KNO3 0,1 M; pH 7; 50 mVs-1

Results of Resistance measurements

Resistance of PANI y PSPANI on a switch electrode.

1,3x1041,1x107Buffer PIPES pH 7

1,9x1034,1x104Buffer acetic0,1 M pH 4,7

1,7x1031,7x103H2SO4 1,8 M

R de PSPANI [Ω]

R de PANI [Ω]

Media

Sensor based on PSPANI and HRP

PSPANICarbon Electrodes

p-phenylendiamine

HRP or MP-11

Works at pH 7!!

Results for HRP (current curves)

iDrain vs t de switch de PAni sultonada a T amb. con HRP o MP-11 inmovilizada con p-fenilendiamina. HEPES 0,1 M KNO3 0,1 M pH 7

(EDrain=20 mV)(EGate=0 V vs Ag/AgCl) Se agregó a t=~50 s H2O2 hasta llegar a la concentración correspondiente

0

2

4

6

8

10

12

0 100 200 300 400 500 600 700 800

t [s]

i [A]

0,1 mM HRP

0,2 mM HRP

0,3 mM HRP

0,5 mM HRP

1 mM HRP

Results for MP-11 (current curves)

iDrain vs t de switch de PAni sultonada a T amb. con MP-11 inmovilizada con p-fenilendiamina. HEPES 0,1 M KNO3 0,1 M pH 7

(EDrain=20 mV)(EGate=0 V vs Ag/AgCl) Se agregó a t=~50 s H2O2 hasta llegar a la concentración correspondiente

0

2

4

6

8

0 100 200 300 400 500 600 700 800

t [s]

i [A]

0,025 micro

0,05 micro

0,1 micro

0,2 micro

0,3 micro

0,5 micro

1 micro

Calibration Curve for: MP-11

Velocidad máxima normalizada de switch de PAni sultonada una noche a T amb. con microperoxidasa MP-11 inmovilizada

con p-fenilendiamina. MOPSs 0,05 M KNO3 0,1 M pH 7 (EDrain=20 mV)(EGate=0 V vs Ag/AgCl) vs Concentración

y = -0.0377xR2 = 0.9776

-4.00E-02

-3.50E-02

-3.00E-02

-2.50E-02

-2.00E-02

-1.50E-02

-1.00E-02

-5.00E-03

0.00E+00

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Concentración [mM]

Velo

cida

d m

áx

norm

aliz

ada[1

/s]

Calibration Curve for: MP-11

Taking slope of the first seconds as criterion

Pendiente de los 1° segundos de switch de PAni sultonada una noche a T amb. con microperoxidasa MP-11 inmovilizada con p-

fenilendiamina. MOPSs 0,05 M KNO3 0,1 M pH 7 (EDrain=20 mV)(EGate=0 V vs Ag/AgCl) vs Concentración

y = -0.2432x + 0.0066R2 = 0.9893

-2.50E-01

-2.00E-01

-1.50E-01

-1.00E-01

-5.00E-02

0.00E+00

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Concentración [mM]

Pend

ient

e de

los

1°

seg.

[ µA/

s]

Conclusions:

•Certain independence between conductivity of PANI and pH can be achieved•The procedure can be made simple and fast by changing reaction temperature and time

•A working pH of 7 can be achieved forsensors based on PANI•Analysis time is still too long and must be shortened to optimize the method

Acknowledgement:

•CONICET•Fundación Antorchas

•DQIA y QF-INQUIMAE•Lab group for making me feel at home