MODIFIED ELECTRODES WITH CHITOSAN

AND PLATINUM PARTICLES FOR RAPID

DETERMINATION OF Escherichia coli

Lucy L. Coria Oriundo. Adolfo La Rosa-Toro Gómez.

lcoria@uni.edu.pe – toro@uni.edu.pe

Grupo de Investigación de Electroquímica Aplicada.

Universidad Nacional de Ingeniería. Lima – Perú.

64th Annual Meeting of International Society

of Electrochemistry

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

INTRODUCTION

Chitosan

Platinum Nanoparticles

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

EXPERIMENTAL AND RESULTS

Figure 1. Cyclic voltammograms for GC/Pt electrode in 2mM

H2PtCl6.6H2O solution and 0.5M H2SO4 solution (scan rate: 50mV/s). In

sito shows the stabilized voltammogram for GC electrode at the same

conditions.

-0.3 0.0 0.3 0.6

-5

0

5

j (m

A/m

2)

E vs. Ag/AgCl (V)

0.0 0.7 1.4

-4

0

4

j (m

A/m

2)

E vs. Ag/AgCl (V)

EL

EC

TR

OD

E P

RE

PA

RA

TIO

N A

ND

MO

DIF

ICA

TIO

N

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

EXPERIMENTAL AND RESULTS

Figure 2. Cyclic voltammograms for GC/CTS/Pt electrode in 2mM

H2PtCl6.6H2O solution and 0.5M H2SO4 solution (scan rate: 50mV/s). In

sito shows the stabilized voltammogram for GC electrode at the same

conditions.

-0.3 0.0 0.3 0.6

-8

0

8

j (m

A/m

2)

E vs. Ag/AgCl (V)

0.0 0.7 1.4

-4

0

4

j (m

A/m

2)

E vs. Ag/AgCl (V)

EL

EC

TR

OD

E P

RE

PA

RA

TIO

N A

ND

MO

DIF

ICA

TIO

N

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

EXPERIMENTAL AND RESULTS

Figure 3. Stabilized voltammograms for GC/CTS electrode in 0.5M

H2SO4 solution. In sito shows the stabilized voltammogram for GC

electrode to 100mV/s

0.0 0.7 1.4

-2

-1

0

1

2

CTS/GC 100mV/s

CTS/GC 50mV/s

j (m

A/m

2)

E vs. Ag/AgCl (V)

0.0 0.7 1.4

-4

0

4

j (m

A/m

2)

E vs. Ag/AgCl (V)

CH

AR

AC

TE

RIZ

AT

ION

OF

ELE

CT

RO

DE

S

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

EXPERIMENTAL AND RESULTS

Figure 4. Peak current against square root of scan rate for GC/CTS

electrode.

CH

AR

AC

TE

RIZ

AT

ION

OF

ELE

CT

RO

DE

S

4 8 12

20

40

60

80

i p (

uA

)

v1/2

(mV.s-1)

1/2

Equation y = a + b*x

Adj. R-Square 0.99242

Value Standard Error

B Intercept 0.14723 2.48134

B Slope 5.57196 0.24332

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

EXPERIMENTAL AND RESULTS

Figure 5. Stabilized voltammograms for GC/Pt electrode in 0.5M

H2SO4 solution. In sito shows the stabilized voltammogram for Pt

polycristaline. (scan rate: 100mV/s)

CH

AR

AC

TE

RIZ

AT

ION

OF

ELE

CT

RO

DE

S

0.0 0.7 1.4

-8

0

8

j (m

A/m

2)

E vs. Ag/AgCl (V)

0.0 0.7 1.4

-20

-10

0

10

j (m

A/m

2)

E vs. Ag/AgCl (V)

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

EXPERIMENTAL AND RESULTS

Figure 6. Stabilized voltammograms for GC/CTS/Pt electrode in 0.5M

H2SO4 solution. In sito shows the stabilized voltammogram for Pt

polycristaline. (scan rate: 100mV/s)

CH

AR

AC

TE

RIZ

AT

ION

OF

ELE

CT

RO

DE

S

0.0 0.7 1.4

-40

-20

0

20

j (m

A/m

2)

E vs. Ag/AgCl (V)

0.0 0.7 1.4

-20

-10

0

10

j (m

A/m

2)

E vs. Ag/AgCl (V)

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

EXPERIMENTAL AND RESULTS

CH

AR

AC

TE

RIZ

AT

ION

OF

ELE

CT

RO

DE

S

ElectrodeReal Surface area

(cm2)

GC/Pt 0.16

GC/CTS/Pt 1.18

Figure 7. Stabilized voltammograms for GC/CTS/Pt and GC/Pt

electrodes in 0.5M H2SO4 solution. (scan rate: 100mV/s)

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

EXPERIMENTAL AND RESULTS

CH

AR

AC

TE

RIZ

AT

ION

OF

ELE

CT

RO

DE

S

Figure 8. AFM images for (a) GC/CTS, (b) GC/Pt and (c) GC/CTS/Pt

electrodes.

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

EXPERIMENTAL AND RESULTS

ELE

CT

RO

CH

EM

ICA

L R

ES

PO

NS

E

Figure 9. System analysis for determination of Escherichia coli.

R E

E L

F E

E C

R T

E R

N O

C D

E E

M E

O L

D E

I C

F T

I R

E O

D D

E

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

EXPERIMENTAL AND RESULTS

ELE

CT

RO

CH

EM

ICA

L R

ES

PO

NS

E

0 1 2 3

360

370

380

390E

(m

V)

Log UFC (u.a)

Equation y = a + b*x

Adj. R-Square 0.9898

Value Standard Error

E Intercept 362.52292 0.68071

E Slope 10.71231 0.44351

Figure 10. Calibration curves for GC/CTS/PtNPs electrode in

presence of different concentrations of Escherichia coli.

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

EXPERIMENTAL AND RESULTS

ELE

CT

RO

CH

EM

ICA

L R

ES

PO

NS

E

Table 1.Comparison between both first and second assays for all

modified electrodes.

Electrode

1° Assay 2° Assay

Intercept Slope R2 Intercept Slope R2

GC 224.26 17.585 0.95351 220.35 17.474 0.95904

GC/CTS 252.39 18.850 0.98390 250.66 18.807 0.97970

GC/PtNPs (10mV/s) 357.25 1.4203 0.95452 357.08 1.5075 0.97581

GC/PtNPs (30mV/s) 431.31 10.019 0.96417 431.27 10.011 0.97413

GC/PtNPs (50mV/s) 358.02 6.8986 0.97486 357.89 6.8250 0.97707

GC/CTS/PtNPs

(10mV/s)384.85 13.072 0.99277 379.36 13.084 0.99431

GC/CTS/PtNPs

(30mV/s)296.08 8.9565 0.98896 292.83 8.8956 0.99011

GC/CTS/PtNPs

(50mV/s)368.19 10.850 0.98863 362.52 10.712 0.98980

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

EXPERIMENTAL AND RESULTS

ELE

CT

RO

CH

EM

ICA

L R

ES

PO

NS

E

Figure 11. Potenciommetric response of GC/CTS/PtNPs electrode in

presence of low and in excess concentrations of Escherichia coli.

0 2000 4000

360

370

380

390E

(m

V)

E. Coli (UFC)

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

CONCLUSIONS

Modified electrodes with chitosan and PtNPs (different

scan rates) were prepared and characterized by cyclic

voltammetry and AFM.

Modified electrodes were used to determinate

cuantitatively presence of Escherichia coli by

Potenciommetric method in sodium sulphate solution.

The results were compare with GC electrode, and to

different assay, obtaining better results for

GC/CTS/PtNPs prepared with 50mV/s scan rate.

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

GRUPO DE INVESTIGACIÓN DE

ELECTROQUÍMICA APLICADA

64th Annual Meeting of International Society of

Electrochemistry

10/09/2013Grupo de Investigación de Electroquímica Aplicada. UNI – FC. Lima, Perú

ACKNOWLEDGEMENTS

CONSEJO NACIONAL DE CIENCIA Y TECNOLOGÍA

(CONCYTEC)

INSTITUTO PERUANO DE ENERGÍA NÚCLEAR

FACULTAD DE CIENCIAS – UNIVERSIDAD

NACIONAL DE INGENIERÍA