i

PORTABLE VOLTAMMETRIC DEVICE FOR DETECTING HEAVY

METAL CONTAMINATION

PHAKHAMON THIPNET

A DISSERTATION SUBMITTED IN PARTIAL FULFILLMENT OF

THE REQUIREMENTS FOR THE DOCTOR DEGREE OF

PHILOSOPHY IN ENVIRONMENTAL SCIENCE

FACULTY OF SCIENCE

BURAPHA UNIVERSITY

DECEMBER 2016

COPYRIGHT OF BURAPHA UNIVERSITY

iii

ACKNOWLEDGEMENT

This Ph.D. dissertation was written based on my research work carried out at

Graduate School Program in Environmental Science, Faculty of Science, Burapha

University. I would like to express my sincere gratitude and deep appreciation to my

major advisor, Asst. Prof. Dr. Pichan Sawangwong and and my Co-advisor,

Asst. Prof. Dr. Chaisak Issro, for all of their guidance and valuable advice throughout

this study.

I would also like to express my heartfelt gratitude to principal examiner

Dr. Palakorn Boonsai, Asst. Prof. Dr. Pichan Sawangwong, Asst. Prof. Dr. Chaisak

Issro, and Dr. Thanawee Chodjarusawad as examining committees for giving me

valuable guidance and expertise in research and taking up the examination job.

I would like to acknowledge all faculty staffs and friends at Burapha

University, Great appreciation is also given to Satit “Piboonbumpen” Burapha

University, my working organization, for giving me a chance to continue my study in

the Doctor Degree of Philosophy in Environmental Science at Burapha University.

For all of the lecturers, staffs, and friends in Graduate School Program in

Environmental Science, Burapha University, sincere thanks for your support,

attention, and motivation.

Finally, heartfelt thanks to my family, my husband Mr.Panitan Thipnet and

my two sons for persistent and endless support thorough my life and the long years of

study. Great respect to Asst. Prof. Dr. Pichan Sawangwon for your loving, patience,

caretaking, attention, and support throughout my study in both of Burapha University.

I offer special thanks to all my friends for your giving kindness, helping, solidarity,

and togetherness.

Phakhamon Thipnet

iv

52810250: MAJOR: ENVIRONMENTAL SCIENCE; Ph.D.

(ENVIRONMENTAL SCIENCE)

KEYWORDS: HEAVY METAL/ ELECTROCHEMICAL TECHNIQUES/

VOLTAMMETRIC TECHNIQUES/ MICROCONTROLLER/

CYCLIC VOLTAMMETRY

PHAKHAMON THIPNET: PORTABLE VOLTAMMETRIC

DEVICE FOR DETECTING HEAVY METAL CONTAMINATION

ADVISORY COMMITTEE: PICHAN SAWANGWONG, Ph.D., CHAISAK ISSRO,

Ph.D. 90 P. 2016.

In this work, an alternative voltammetric procedure for the simultaneous

determination of lead (Pb), cadmium (Cd) and copper (Cu) were developed by using

microcontroller for inventing portable cyclic voltammetry. The electrode that used

gold wire, silver wire and platinum wire for working electrode, counter electrode and

reference electrode respectively. The electrode can be easily prepared and showed a

good analytical response was linear in the range of 10 µg L-1

to 50 µg L-1

. Successive

cyclic voltammograms of gold electrode and scan start voltage -1.30 V to 1.3 V at

room temperature. The high sensitivity and good reproducibility of the nontoxic gold

wire, platinum wire and silver wire electrode make it possible to apply the electrode

to a portable system for a trace metal analysis. The portable voltammetric device for

detecting heavy metal contamination is easily taken, used and low cost. Finally, the

portable voltammetric device for detecting heavy metal contamination was applied for

the analysis of lead cadmium and copper with satisfactory results.

v

CONTENTS

Page ABSTRACT ............................................................................................................. iv

CONTENTS .............................................................................................................. v

LIST OF TABLES .................................................................................................. vii

LIST OF FIGURES ............................................................................................... viii

CHAPTER

1 INTRODUCTION ............................................................................................. 1

Statements and significance of the problems ............................................ 1

Objectives ................................................................................................. 2

Conceptual Framework ............................................................................. 2

Scope of Research ..................................................................................... 2

Expected Results ....................................................................................... 3

Definition of terms .................................................................................... 3

2 LITERATURE REVIEWS ................................................................................ 6

Heavy metal Analysis ............................................................................... 6

The Electrodes and Cell ............................................................................ 13

Cyclic voltammetry (CV) ......................................................................... 14

Microcontroller Arduino UNO r3 ............................................................. 17

3 RESEARCH METHODOLOGY ..................................................................... 18

Equipment and Apparatus ........................................................................ 18

Electronic Equipment for Portable voltammetric device ......................... 18

Chemicals ................................................................................................. 19

Solution Preparation................................................................................. 19

Experimental design................................................................................. 21

Step for study electrode efficiency .......................................................... 35

Procedure for GFAAS.............................................................................. 38

vi

CONTENTS (CONTINUED)

Chapter Page

4 RESULTS ......................................................................................................... 39

5 CONCLUSION................................................................................................. 55

Discussions .............................................................................................. 55

Conclusion ............................................................................................... 57

REFERENCES ........................................................................................................ 58

APPENDIX .............................................................................................................. 62

APPENDIX A ................................................................................................... 63

APPENDIX B ................................................................................................... 85

BIOGRAPHY .......................................................................................................... 90

vii

LIST OF TABLES

Table Page

2-1 Detection methods for the analysis of heavy metals in herbal, tea and

herbal teas ...................................................................................................... 7

2-2 Electrochemical techniques ........................................................................... 11

3-1 Preparation of stock solution (10, 20, 30 and 50 µg L-1) ............................. 21

3-2 Preparation of mixture solution ..................................................................... 21

3-3 Acetate buffer for supporting electrolyte (p H) ............................................. 36

3-4 Concentration of standard solution ............................................................... 37

3-5 concentrations of standard solutions (Pb, Cd and Cu) for calibration curve . 37

3-6 Limit detection of heavy metal by GFAAS .................................................. 38

viii

LIST OF FIGURES

Figure Page

1-1 Electrode for detecting heavy metal ............................................................... 2

2-1 Scheme of the CV ........................................................................................ 15

2-2 Course of the potential ................................................................................. 16

3-1 Diagram Preparation the electrode ................................................................ 23

3-2 A three-electrode was employed for Portable voltammetric device for

detecting heavy metal contamination (cyclic voltammetry) ......................... 24

3-3 Graphite pencil and Graphite electrode ......................................................... 24

3-4 Portable voltammetric device for detecting heavy metal contamination

circuit ............................................................................................................. 26

3-5 Portable voltammetric device for detecting heavy metal contamination ...... 27

3-6 The step for the program on Portable voltammetric device for detecting

heavy metal contamination ............................................................................ 28

3-7 Show electrode testing on mix standard solution of lead (Pb), cadmium

(Cd) and copper (Cu) ..................................................................................... 36

4-1 Successive cyclic voltammograms of Lead (Pb) in acetate buffer

(a) pH 3.5 (b) pH 5.5 and (c) pH 7.5 ............................................................. 41

4-2 Successive cyclic voltammograms of Lead (Pb) on gold wire silver wire

and platinum wire electrode (a) gold wire (b) silver and (c) platinum wire 43

4-3 Successive cyclic voltammograms of Graphite pencil electrode (a) DI

water (b) Lead (Pb) (c) cadmium (Cd) and (d) Copper (Cu) ........................ 45

4-4 Successive cyclic voltammograms (a) Deionized water (b) Lead

(II) 20 µg L-1 (c) Cadmium (II) 20 µg L-1 and (d) Copper (II) 20µg L-1 ... 47

4-5 Successive cyclic voltammograms (a) Lead (II) 10 – 50 µgL-1 (b)

Cadmium (II) 10 – 50 µgL-1 and (c) Copper (II) 10 – 50 µgL-1 ................. 49

4-6 Dependency of the peak current on the concentration of (a) Lead (II)

10-50 µgL-1 (b) Cadmium (II) 10-50 µgL-1 and

(c) Copper (II) 10-50 µgL-1 .......................................................................... 51

ix

LIST OF FIGURES (CONTINUED)

Figure Page

4-7 The results for the simultaneous detection of lead (Pb) cadmium (Cd) and

copper (Cu) in 5 sample water (a) sample water number 1 (b) sample water

number 2 (c) sample water number 3 (d) sample water number 4 (e)

sample water number 5 .................................................................................. 54

1

CHAPTER 1

INTRODUCTION

Statements and significance of the problems

The herbal beverage is one of the most widely consumed beverages in the

world. Drinking herbal beverage might help reduce serum cholesterol, provide anti-

aging activities, and decrease the risks of both cardiovascular disease and cancer.

However, heavy metal contaminants might accumulate during herbal growth,

transportation, packing, and processing. Heavy metals are harmful to human health.

Lead Cadmium and Copper are serious environmental pollutants, which are

highly toxic to human nervous, immune, reproductive, and gastrointestinal systems.

Moreover, these heavy metals are inclined to persistently retain in the ecosystem and

bio-accumulate in human body through food chain. Nevertheless, heavy metals have

been extensively exploited and discharged in various manufacturing, mining and

casting industry, causing a wide dispersion in the environment. Among all approaches

that are capable of trace heavy metal detection, Inductively coupled plasma-optical

emission spectrophotometry (ICP-OES) (Gorur, Keser, Akcay, Dizman, &

Okumusoglu, 2011) Atomic absorption spectroscopy (AAS) (Grzesik & Kolon, 2008)

Graphite furnace atomic absorption spectrometry (GFAAS) (Ning, Gong, Zhang,

Guo, & Bai, 2011) and inductively coupled plasma mass spectroscopy (ICP-MS)

(Milania, Morganoa & Cadoreb, 2016) are the commonly used methodologies.

However, that methodologies always require expensive instrumentation, complicated

operation procedures, long detection period and skill personnel.

Electrochemical methods, especially electrochemical stripping analysis,

have been widely recognized as a powerful tool for determination of heavy metals due

to Its low cost, easy operation, high sensitivity and selectivity. Traditionally, mercury

electrodes are employed for stripping analysis. However, the toxicity of mercury

makes it undesirable for sensing application, particularly those involving food

contacts. A grate variety of electrode materials has been proposed as alternative such

as gold, platinum, carbon, graphite, etc.

2

This research will be conducted to design and invent portable voltammetric

device for detecting heavy metal contamination.

Objectives

To design and invent portable voltammetric device for detecting heavy metal

contamination.

To study electrochemical techniques for detecting heavy metal.

To study successive cyclic voltammograms.

Conceptual Framework

Figure 1-1 Electrode for detecting heavy metal

Scope of Research

1. To design and invent portable voltammetric device for detecting heavy

metal contamination.

1.1 Electrode type I: platinum wire, silver wire, gold wire

1.2 Electrode type II: platinum wire, silver wire, graphite pencil

2. Invent meter, Voltmeter Ammeter and Power Supple

3. To study electrochemical techniques for detecting lead (Pb) Cadmium

(Cd) and copper (Cu) by compare electrode efficiency. (Electrode type I: platinum

wire, silver wire, gold wire and Electrode type II: platinum wire, silver wire, graphite

pencil)

3

3.1 Standard solution of lead (Pb), cadmium (Cd) and copper (Cu)

3.2 Mix standard solution of lead (Pb), cadmium (Cd) and copper (Cu)

3.3 Voltage -1.3 to 1.3 V

3.4 Successive cyclic voltammograms.

4. Testing for detect heavy metal in standard solution and sample water

compared GFAAS

Expected Results

1. The portable voltammetric device for detecting heavy metal

contamination.

2. Electrochemical techniques for detecting lead (Pb), Cadmium (Cd) and

copper (Cu) in sample water is easily taken, used and low cost.

Definition of terms

Heavy metal is the element with both value and toxicity of living things.

Metals can be toxic to biological systems. By definition, a heavy metal heavy metal is

a substance that has a specific gravity greater than 4 and 5, and considering the

position on the periodic table of elements included in the heavy metals. Atomic

number between 22-23 and between 40-52, including the rare earth elements, and

actinides and substances affect the biochemistry of plants and animals. There are 22

kinds of heavy metals such as Cu, Zn, Cd, Pb and Mn etc.

Electrochemical techniques give information on the processes taking place

when an electric potential is applied to the system under study. The Voltalab 40

equipment generates direct and alternate current. Thus, different electrochemical

methods can be applied such as determination of the corrosion potential, Tafel curves,

anodic polarization curves, electrochemical impedance spectroscopy, etc. All these

electrochemical analysis provide information of important parameters (corrosion rate,

polarization resistance, protection potential, repassivation potential, breakdown

potential). Depending on the electrochemical system, the most suitable method may

be applied with the aim of determining the corrosion behaviour of the material.

Similarly, the corrosion resistance can be evaluated before an after a protective

4

coating is grown on the material surface to verify the protective character of the outer

film.

Voltammetry is one of several important analytical techniques for the

analysis of trace metals in environmental samples, including groundwater, lakes,

rivers and streams, seawater, rain, and snow. Detection limits at the parts-per-billion

level are routine for many trace metals using differential pulse polarography, with

anodic stripping voltammetry providing parts-per-trillion detection limits for some

trace metals.

Voltammetric methods used only two electrodes, a modern voltammeter

makes use of a three-electrode potentiostat, In voltammetry we apply a time-

dependent potential excitation signal to the working electrode changing its potential

relative to the fixed potential of the reference electrode and measure the current that

flows between the working and auxiliary electrodes. The auxiliary electrode is

generally a platinum wire, and the reference electrode is usually a SCE or a Ag/AgCl

electrode.

5

CHAPTER 2

LITERATURE REVIEWS

Heavy metal Analysis

1. The techniques for analyze heavy metal

Numerous techniques have been employed to analyze the heavy metal

contents in herb, beverage and herbal tea, including atomic absorption spectrometry

(AAS), flame atomic absorption spectrometry (FAAS), graphite furnace atomic

absorption spectrometry (GFAAS), Inductive Coupled Plasma Spectrometer (ICPS),

inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma

optical emission spectrometry (ICP-OES), direct competitive enzyme-linked

immunosorbent assay (DC-ELISA) inductively coupled plasma atomic emission

spectroscopy (ICP-AES), and polarised X-rays fluorescence spectrometer (EDPXRF)

Soylak, Tuzen, Mendil, and Turkekul (2006) reported of copper (II), lead

(II) and zinc (II) on Aspergillus fumigatus immobilized Diaion HP-2MG resin from

tea and black tea. Analysed by FAAS. The detection limits were 0.30 µg/L for copper,

0.41 µg/L for zinc, 0.52 µg/L for lead.

Seenivasan, Manikandan, Muraleedharan, and Selvasundaram (2008)

presented of heavy metals in black tea were analyzed uanalyzed using FAAS and

GFAAS. The results of analysis showed that the mean level of Cu was 24.07 ± 2.25

mg/ kg, Cd 0.14 ± 0.06 mg/kg and 0.81 ± 0.32 mg/ kg

Karimi et al. (2008) studied the concentration of Cu and Pb were determined

by AAS on black tea. The results showed Cu content in investigated teas ranged from

17.59 to 32.80 µg/g and Pb 2.08 to 2.59 µg/g

Grzesik and Kolon (2008) reported the content of Cd and Pb in fruit tea was

analyzed by GFAAS. The maximum obtained values for leaching of cadmium from

fruit teas 8.6%. Lead is more easily leached from the studied materials than cadmium-

maximum values 35.2% for fruit teas have been found.

Tuzen, Soylak, and Elci (2005) reported an FAAS method with multi-

element preconcentration procedure for the determination of Cd, Pb and other metal

6

ions. The reusability of Chromosorb 108 was as high as 200 cycles without any loss in

its sorption behavior. LODs for Cd and Pb were 0.16-0.6 μg/L in black tea.

Duran, Ozdes, Sahin, Bulut, Gundogdu, and Soylak (2011) demonstrated a

sensitive and environmentally friendly separation and preconcentration procedure for

FAAS determination of Cu (II) and Cd (II). The samples were prepared based on the

carrier element free co-precipitation with an organic co-precipitant. The higher

preconcentration factor was 50 and the LODs for Cu (II) and Cd (II) were 1.49 and

0.45 μg/L, respectively.

Dasbas, Sacmac, Ulgen, and Kartalb (2015) presented for the determination

of cadmium (II) and lead (II) in various food and water samples. The detection limits

for Cd (II) and Pb (II) were found as 0.13 and 0.18 μg/L, respectively

Zhong, Ren, and Zhao (2016) studied the contents of Pb, Cd, Cr, Cu, and Ni

in tea produced and marketed in China were analyzed using high-resolution

continuum source graphite furnace atomic absorption spectrometry (HRCSG-FAAS).

The Pb, Cu, and Ni levels in green tea were much higher than those in the other types

of tea; the highest total content (76.47 mg/kg) was found in the Maojian tea.

Ning et al. (2011) studied the investigation of Pb, Cd, and Cu contents in 30

brands of Chinese Pu'er tea using GFAAS and observed that the Cu contents

(12.22- 22.22 mg/kg) were the highest.

Rubio et al. (2012) reported Pb Cd Cu concentrations in mentha herbal teas

by ICPS. Pb analyses revealed levels (0.65 ± 0.71 mg/kg), Cd 0.3 mg/kg and Cu

10.65 mg/kg

Arpadjan, Celik, Taskesen, and Gucer (2008) studied toxic elements were

present in the medicinal plants As 12–225 mg/kg, Cd 15–268 mg/kg and Pb 0.2-8.6

mg/kg by ICP-MS.

Malik et al. (2013) The determination of Al, B, Cu, Fe, Mn, Ni, P, Zn and

Ca, K, Mg by inductively coupled plasma optical emission spectrometry (ICP-OES)

and flame atomic absorption spectroscopy (FAAS)

Gorur et al. (2011) reported level determined the concentrations of Pb, Fe,

Mn, Zn and Cu in 29 black tea and one green tea samples from Turkey by using

7

ICP-OES. The results indicated that Pb content in these tea samples was below the

LOD (0.0119 mg/L) and the concentrations of all elements for daily intake were in

safety levels for human consumptions.

Liu et al. (2009) studied enzyme-linked immune sorbent assay (DC-ELISA)

based on a cadmium-chelate-specific monoclonal antibody has been developed. The

DC-ELISA showed an IC50 of 2.30 μg/L with a detection limit of 0.20 μg/L for

cadmium.

Desideri, Meli, Roselli, and Feduzi (2011) studied herbal tea and camomile

were determined by polarised X-rays fluorescence spectrometer (EDPXRF). The

results showed that Cd was below 0.5 mg/kg, Pb 0.5-4.3 mg/kg, Hg below 0.1 mg/kg

and Sn 1.1-1.5 mg/kg.

The conclusion from the details is show in table 2-1

Table 2-1 Detection methods for the analysis of heavy metals in herbal, tea and

herbal teas.

Sample Analyte Method Reference

Black tea Cu Pb Zn FAAS Soylak et al. (2006)

Black tea Cd Cu Cr AAS Seenivasan et al. (2008)

Black tea Pb Cu AAS Karimi et al. (2008)

Fruits tea Cd Pb AAS Grzesik and Kolon (2008)

Black tea Pb Cd Cu FAAS Tuzan et al. (2005)

Black tea Cd Cu FAAS Duran et al. (2011)

Tea Cd Pb FAAS Dasbasi et al. (2015)

Green tea

Maojian tea

Pb Cd Cr Cu FAAS

(HRCSG-FAAS)

Zhong et al. (2016)

Pu'er tea Pb Cd Cu GFAAS Ning et al. (2011)

Herbal tea Cd Cu Pb ICPS Rubio et al. (2012)

Herb Pb, Cd ICP-MS Arpadjan et al. (2008)

Tea Pb Cd Cu ICP-MS Milani et al. (2016)

Herbal tea Al ICP-OES Malik et al. (2013)

8

Table 2-1 (Continued)

Sample Analyte Method Reference

Black tea and

Green tea

Pb Fe Zn ICP-OES Gorur et al. (2011)

Tea Cd DC-ELISA Liu et al. (2009)

Herbal tea and

Camomile

Pb Cd EDPXRF Desideri et al. (2011)

2. Electroanalytical application for the trace determination of metals

Electrochemical analysis is a powerful analytical technique that is utility in

Pharmaceutical industry, metal industry, and environmental applications. Electro

analysis of high advantages due to high sensitivity, reduction in solvent and sample

consumption, high-speed analysis, low operating cost and high scan rate in all cases.

Several Electrochemical techniques, such as voltammetry. Carbon electrode

have been widely used for voltammetric analysis. These techniques were well

established for the low cost production, reproducibility, and ease the miniaturization.

Numerous advantages diversified chemicals of food quality, clinical and

environmental interest and sensitive electrochemical sensors, Screen-printed sensors

have been widely used for environmental, biomedical and industrial monitoring.

Krolicka et al. (2002) studied the bismuth film electrode designed for

voltammetry stripping analysis of some heavy metals such as Pb, Cd and Zn

Kefala, Economou, Voulgaropoulos, and Sofoniou (2003) reported the

simultaneous determination of Cd (II), Pb (II) and Zn (II) at the low mgl/1

concentration levels by square wave anodic stripping voltammetry (SWASV) on a

bismuth-film electrode (BFE) plated in situ. The metal ions and bismuth were

simultaneously deposited by reduction at -1.4 V on a rotating glassy carbon disk

electrode.

Hwang, Han, Park, and Kang (2008) used bismuth-modified carbon

nanotube electrode (Bi-CNT electrode) was employed for the determination of trace

lead, cadmium and zinc. Prepared bismuth onto the screen-printed CNT electrode.

The peak current response increased linearly with the metal concentration in a range

9

of 2-100 microg/L. The limit of detection was 1.3 microg/L for lead, 0.7 microg/L for

cadmium and 12 microg/L for zinc. The Bi-CNT electrode was successfully

applicable to analysis of trace metals in real environments.

Rehacek, Hotovy, Vojs, and Mika (2008) used graphite disc electrode

(0.5 mm in diameter) from a pencil-lead rod. The disc graphite was used for

simultaneous determination of Pb (II), Cd (II) and Zn (II) by square wave

voltammetry (SWV) in an aqueous solution. Detection limits 2.4 x 10–9

mol/L for Pb

(II), 2.9 x 10–9

mol/L for Cd (II) and 1.2 x 10–8

mol/L for Zn (II).

Tarleya, Santosa, Baêtaa, Pereirab, and Kubota (2009) reported a multiwall

carbon nanotube electrode on potentiometric stripping analysis at -1.3 V and The

limits of detection for Zn (II), Cd (II) and Pb (II) were found to be 28.0,8.4 and

6.6 µg/L,

Injanga, Noyroda, Siangprohb, Dungchaia, Motomizuc, and Chailapakulad

(2010) studied anodic stripping voltammetry (SIA-ASV) by using screen-printed

carbon. the linear ranges were found to be 2-100 µg/L for Pb (II) and Cd (II), and

12-100 µg/L for Zn (II). The limits of detection were 0.2 µg/L for Pb (II), 0.8 µg/L for

Cd (II) and 11 µg/L for Zn (II). The measurement frequency was found to be

10-15 stripping cycle for 60 sec.

Guo, Chai, Yuan, Song, and Zou (2011) reported the carbon paste electrode

response to Pb2+

ion ranging from 5.9×10−10

to 1.0×10−2

M with a detection limit of

3.2×10−10

M. The concentrations of Pb2+

ions were determined by the carbon paste

electrode and AAS.

Anandhakumar and Mathiyarasu (2012) reported bismuth film modified

carbon fiber detection of Cd (II) and Pb (II). As compared to the unmodified

electrode. Electro analysis using square ware anodic stripping voltammetry linear

response over the 50-500 nM range.

Jothimuthu et al. (2013) studied zinc in serum detection by ASV as

compared with the AAS and ICP-MS. The results show Zn detection in serum rage

5 µM to 50 µM.

Raj, Raina, Mohineesh, and Dogra (2013) direct determination of Zn, Cd, Pb

and Cu metal was carried out from tap water using differential pulse anodic stripping

Voltammeter. As a result the concentration observed in the tap water sample was

10

determined as 0.174 mg/L, 0.001 mg/L, 0.002 mg/L, 0.011 mg/L respectively.

The advantages of the proposed Voltammetric method over the other AAS, ICPOES

techniques.

Tufa, Sirajz, and Soreta (2013) Electrochemical application of bismuth film

modified glassy carbon electrode was studied with the objective of lead detection.

Three linear calibration plots in the range 7.5 nmol/L to 0.1 μmol/L, 0.25 to 1 μmol/L,

2.5 to 12.5 μmol/L. as compared with the AAS.

Wang, Wang, Zhang, and Liu (2014) studied determination of trace lead and

cadmium ions by square wave anodic stripping voltammetry (SWASV). the linear

range of electrode was from 1.0 to 80.0 µg/L for lead and cadmium. The electron

transfer kinetics of a redox probe at electrodes were tested by electrochemical

impedance spectroscopy (EIS).

Hevia, Arancibia, and Romo (2015) presented an adsorptive stripping

voltammetric method for the determination of Cu (II) at trace levels in sweeteners,

sugar and tea. The relationship between the peak current and copper concentration is

linear in the range 0.33-65.0 μg/L. The sensitivity with a short accumulation time is

better than that for AAS and ICP-AES

Salih, Ouarzane, and Rhazi (2015) studied new sensor based on carbon paste

electrode modified with Poly (1,8-diaminonaphthalene) and bismuth film (Bi-Poly1,

8-DAN/CPE) was prepared and characterized with cyclic voltammetry and

electrochemical impedance spectroscopy (EIP). The sensing of lead show linear range

was achieved over concentration range from 0.5 µg/L to 50 µg/L, with a detection

limit of 0.3 µg/L.

Wan et al. (2015) presented a fast and sensitive approach for simultaneous

electrochemical determination of lead and copper based on a commercial screen-

printed gold electrode (SPGE) with gold nanoparticles (GNPs) modification in cyclic

voltammetry (CV) and square wave anodic stripping voltammetry (SWASV).

Compared to that of merely activated SPGE. To detect lead and copper a sensitivity of

0.154 µA/ppb and 0.084 µA/ppb.

Birinci, Eren, Coldur, Coskun, and Andac (2016) studied a new solid contact

copper selective electrode with a poly (vinyl chloride) (PVC) electrode response to

11

Cu2+

activity from 10-1

to 10-6

mol/L. The studied compared favorably with those

obtained by the atomic absorption spectroscopy (AAS).

The Summarize for Electroanalytical application for the trace determination

of metals in table 2-2

Table 2-2 Electrochemical techniques

Sample Analyte Voltammetric

technique

Working

electrode

Compared References

Standard

solution

Pb Cd

Zn

SV Carbon-

electrode

BAS

volumetric

analyzer

Krolicka et al.

(2002)

Tap

water,

human

hair

Pb Zn ASV Bismuth

electrode

AAS Kefala et al.

(2003)

River

water

Pb Cd

Zn

ASV Bi- CNT

electrode

ICP-MS Hwang et al.

(2008)

Standard

solution

Pb Cd

Zn

ASV Graphite

electrode

DPV Rehacek et al.

(2008)

Lake,

Water

sample

Pb Cd

Zn

PAS CNT-

electrode

AAS Tarley et al.

(2009)

Herb Pb Cd

Zn

SIA-ASV CNT-

electrode

ICP-AES Injang et al.

(2010)

Black tea Pb PSA Carbon-

electrode

AAS Guo et al.

(2011)

12

Table 2-2 (Continued)

Sample Analyte Voltammetric

technique

Working

electrode

Compared References

Tap water Pb Cd SWASV Carbon

fiber

electrode

Unmodified

electrode

Anandhakumar

et al. (2012)

Tap water Cd Pb

Cu Zn

ASV Mercury

electrode

AAS Raj et al.

(2013)

Standard

solution

Pb ASV Glassy

carbon

electrode

AAS Tufa et al.

(2013)

Rice Pb Cd SWASV Graphene

electrode

EIS Wang et al.

(2014)

Sugar,

Coffee

and tea

Cu SW-ASV Mercury

electrode

AAS, ICP–

AES

Hevia et al.

(2015)

Water

sample

Pb CV Carbon

electrode

EIS Salih et al.

(2015)

Standard

solution

Pb Cu SWASV, CV Gold

electrode

Commercial

electrode

Wan et al.

(2015)

Tea Cu PSA Pvc

electrode

AAS Birinci et al.

(2016)

Standard

solution

Pb Cd

Zn

SV Carbon-

electrode

BAS

volumetric

analyzer

Krolicka et al.

(2002)

Tap

water,

human

hair

Pb Zn ASV Bismuth

electrode

AAS Kefala et al.

(2003)

13

Table 2-2 (Continued)

Sample Analyte Voltammetric

technique

Working

electrode

Compared References

Tap water Pb Cd SWASV Carbon

fiber

electrode

Unmodified

electrode

Anandhakumar

et al. (2012)

Tap water Cd Pb

Cu Zn

ASV Mercury

electrode

AAS Raj et al.

(2013)

Standard

solution

Pb ASV Glassy

carbon

electrode

AAS Tufa et al.

(2013)

Rice Pb Cd SWASV Graphene

electrode

EIS Wang et al.

(2014)

Sugar,

Coffee

and tea

Cu SW-ASV Mercury

electrode

AAS, ICP–

AES

Hevia et al.

(2015)

Water

sample

Pb CV Carbon

electrode

EIS Salih et al.

(2015)

Standard

solution

Pb Cu SWASV, CV Gold

electrode

Commercial

electrode

Wan et al.

(2015)

Tea Cu PSA Pvc

electrode

AAS Birinci et al.

(2016)

The Electrodes and Cell

A typical electrochemical cell consists of the sample dissolved in a solvent,

an ionic electrolyte, and three (or sometimes two) electrodes. Cells (that is, sample

holders) come in a variety of sizes, shapes, and materials. working electrode; in some

cases, to avoid contamination, it may be necessary to place the reference electrode in

a separate compartment. The unique requirements for each of the voltammetric

techniques are described under the individual techniques.

14

Reference Electrodes The reference electrode should provide a reversible

halfreaction with Nernstian behavior, be constant over time, and be easy to assemble

and maintain. The most commonly used reference electrodes for aqueous solutions are

the calomel electrode. These electrodes are commercially available in a variety of

sizes and shapes.

Counter (auxiliary) Electrode In most voltammetric techniques the analytical

reactions at the electrode surfaces occur over very short time periods. Most often the

counter electrode consists of a thin Pt wire, although Au and sometimes graphite have

also been used.

Working Electrodes The working electrodes are of various geometries and

materials, its surface is readily regenerated by producing a new drop or film, and

many metal ions can be reversibly reduced into it. Other commonly used electrode

materials are gold, platinum, and glassy carbon.

Cyclic voltammetry (CV)

Cyclic voltammetry (CV) has becomes an important and widely used in

many areas of electro analytical chemistry. It is rarely used for the quantitative

determination but it is widely used for study of redox reactions and get much

information about the chemical reactions occurs. Cyclic voltammetry is a rapid

voltage scan technique in which the direction of voltage scan is reversed. While the

applied potential at working electrode in both forward and reverse directions the

resulting current is recorded. The scan rate in the forward and reverse direction is

normally the same. CV can be used in single cycle or multicycle modes.

The cyclic voltammetry is successor of method called polarography that was

awarded for the Nobel Prize Czech native Jaroslav Heyrosvky in 1959. The CV is

belonged to the group of potential-dynamic experimental methods. The investigated

surface is placed in electrolyte and creates the working electrode. The general schema

of setup is in Figure 2-1. Between the working electrode and the counter electrode

goes electric current. The voltage on working electrode is set according to the

reference electrode. The reference electrode is usually made from calomel or Ag-

AgCl. The counter electrode is made from Pt and working electrode is consisted

15

usually of glassy carbon, carbon paste, Au, Pt and crystals that are coated with

investigated catalytic powder.

Figure 2-1 Scheme of the CV.

The measurements are performed that the voltage at working electrode

related to the reference electrode is periodically cycled between two values

(see Figure 2-2) with using potentiostat. The first half of cycle is forward scan

and it is increasing and the second part of cycle is reverse scan and it is decreasing.

The sweep rate is generally from 10 to 200 mV/s. The results are plot current against

voltage an it is called voltammogram. The voltammogram of reversible process is

shown in Figure 2-3

16

Figure 2-2 Course of the potential.

Figure 2-3 The voltammogram of reversible process.

17

Microcontroller Arduino UNO r3

The Uno is a microcontroller board based on the ATmega328P (Figure 2-4).

It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog

inputs, a 16 MHz quartz crystal, a USB connection, a power jack, an ICSP header and

a reset button. It contains everything needed to support the microcontroller; simply

connect it to a computer with a USB cable or power it with a AC-to-DC adapter or

battery to get started. You can tinker with your UNO without worrying too much

about doing something wrong, worst case scenario you can replace the chip for a few

dollars and start over again.

“Uno” means one in Italian and was chosen to mark the release of Arduino

Software (IDE) 1.0. The Uno board and version 1.0 of Arduino Software (IDE) were

the reference versions of Arduino, now evolved to newer releases. The Uno board is

the first in a series of USB Arduino boards, and the reference model for the Arduino

platform; for an extensive list of current, past or outdated boards see the Arduino

index of boards.

Figure 2-4 Microcontroller Arduino UNO r3

This research will be conducted to design and invent portable voltammetric

device for detecting heavy metal contamination (Portable cyclic voltammetry)

18

CHAPTER 3

RESEARCH METHODOLOGY

Equipment and Apparatus

1. Platinum wire

2. Silver wire

3. Gold wire

4. Graphite (Graphite pencil)

5. PCB (printed circuit board)

6. Microcontroller Uno r3

7. Volt meter (mV)

8. Amp meter (µA)

9. Magnetic Stirrer

10. Hot Plate Magnetic Stirrer

11. pH Meter Hanna HI 2223 Calibration Check pH/ORP Meter

12. Balance 4 decimal points

13. Breaker

14. DC Power Supply

15. Volumetric Flask

16. Volumetric pipet

17. Spatula

18. Stand

19. Micropipette

Electronic Equipment for Portable voltammetric device

1. Digital Power supply 0-1.3 V circuit.

2. Negative Power supply circuit -5V

3. Op-Amp Inverting circuit

4. A to D 16 bit Module (ADS1115)

5. LCD Module 16x4

6. Arduino Uno r3

19

7. SD card Module

Chemicals

1. Nitric acid (HNO3 Conc.) (AR Grade, Asia pacific specialty chemical,

Australia)

2. Stock standard solution Pb 1,000 mgL-1

(AR Grade, Merck Darmstadt,

Germany)

3. Stock standard solution Cu 1,000 mgL-1

(AR Grade, Merck Darmstadt,

Germany)

4. Stock standard solution Cd 1,000 mgL-1

(AR Grade, Merck Darmstadt,

Germany)

5. Acetic acid (AR Grade, Asia pacific specialty chemical, Australia)

6. Sodium acetate (AR Grade, Asia pacific specialty chemical, Australia)

Solution Preparation

1. General solution

HNO3 solution, 6M

Pour 39 ml conc.HNO3 from a graduated cylinder into a beaker with 40 ml

deionized water. Add more deionized water until the final volume was 100 ml

2. Electrolyte solution/acetate buffer

2.1 Electrolyte solution I, 50 Mm CH3COONa

2.1.1 Weigh 2.052 g CH3COONa in a beaker and dissolve it in

250 ml. deionized water. Adjust pH to 5.5

2.2 Solution II, 50 Mm CH3COOH

2.2.1 Pipet 0.6 ml. CH3COOH in a beaker and dissolve it in 100 ml.

deionized water.

2.3 Pour the mixture solution I in step 2.1.1 200 ml into 250 ml

volumetric flask and add 32 ml Solution II. (Acetate buffer)

3. Stock standard solution Pb, Cd and Cu

Stock standard solution Pb 1,000 mgL-1

(AR Grade, Merck Darmstadt,

Germany)

20

Stock standard solution Cd 1,000 mgL-1

(AR Grade, Merck Darmstadt,

Germany)

Stock standard solution Cu 1,000 mgL-1

(AR Grade, Merck Darmstadt,

Germany)

(Stock standard solution from Institute of Marine Science, Burapha

University

Transfer 10 ml in plastic tube and pack in safety box, keep in refrigerator for

solution)

3.1 Stock standard solution A

Stock standard solution A, volume 100 ml Pb, Cd and Cu 10 µg L-1

Pipet 1.0 ml Stock standard solution Pb in 250 volumetric flask Add more

deionized water until the final volume was 100 ml

Pipet 1.0 ml Stock standard solution Cd in 250 volumetric flask Add more

deionized water until the final volume was 100 ml

Pipet 1.0 ml Stock standard solution Cu in 250 volumetric flask Add more

deionized water until the final volume was 100 ml

3.2 Stock standard solution B, volume 100 ml Pb, Cd and Cu 10, 20, 30

and 50 µg L-1

3.2.1 Pipet 1,10, 20, and 50 ml Stock standard solution A of Pb in 250

volumetric flask Add more deionized water until the final volume was 100 ml

3.2.2 Pipet 1,10, 20, and 50 ml Stock standard solution A of Cd in 250

volumetric flask Add more deionized water until the final volume was 100 ml

3.2.3 Pipet 1,10, 20, and 50 ml Stock standard solution A of Cu in 250

volumetric flask Add more deionized water until the final volume was 100 ml

3.2.4 Follow preparation of stock solution (10, 20, 30 and 50 µg L-1

)

condition as show in Table 3-1

21

Table 3-1 Preparation of stock solution (10, 20, 30 and 50 µg L-1

)

Heavy

metal

Stock A

(ml)

Stock A

(ml)

Stock A (ml) Stock A

(ml)

Stock A

(ml)

Pb 100 1 10 20 50

Cd 100 1 10 20 50

Cu 100 1 10 20 50

Final

Stock B

100 mgL-1

10 mgL-1

20 mgL-1

30 gL-1

50 gL-1

4. Mixture solution

4.1 Mixture solution Stock standard solution Pb,Cd and Cu

4.2 Follow preparation condition as show in Table 3-2

Table 3-2 Preparation of mixture solution

Mixture Pb Cd Cu

Mixture 1 1.0 ml 10 mgL-1

1.0 ml 10 mgL-1

1.0 ml 10 mgL-1

Mixture 2 1.0ml 20 mgL-1

1.0 ml 20 mgL-1

1.0 ml 20 mgL-1

Mixture 3 1.0 ml 30 mgL-1

1.0 ml 30 mgL-1

1.0 ml 30 mgL-1

Mixture 4 1.0 ml 50 mgL-1

1.0 ml 50 mgL-1

1.0 ml 50 mgL-1

Experimental design

Part 1 Preparation the electrode (Figure 3-1)

Part 2 Invent meter, voltmeter ammeter and power supply

Part 3 Comparison of the electrode efficiency in blank and standard solution

Part 4 Testing for detect heavy metal in standard solution and water sample

Part 1 Preparation the electrode

1. Design the PCB (Printed Circuit Board) for electrode

2. Preparation the electrode

22

A three-electrode was employed for Portable voltammetric device for

detecting heavy metal. (cyclic voltammetry). A gold wire was used as the working

electrode. A silver wire and a platinum wire were used as the counter electrode and

reference electrode (Figure 3-2)

2.1 Platinum wire cleaning

2.1.1 Rinse platinum with deionized water thoroughly

2.1.2 Immerse it in 10% HNO3 at room temperature to oxidize

contaminant from Platinum wire surface.

2.1.3 After 10 minutes was reached, rinse it with deionized water

thoroughly and let dry in air.

2.2 Gold wire cleaning

2.2.1 Rinse gold with deionized water thoroughly

2.2.2 Immerse it in 10% HNO3 at room temperature to oxidize

contaminant from gold wire surface.

2.2.3 After 10 minutes was reached, rinse it with deionized water

thoroughly and let dry in air.

2.3 Silver wire cleaning

2.3.1 Rinse silver with deionized water thoroughly

2.3.2 Immerse it in 10% HNO3 at room temperature to oxidize

contaminant from silver wire surface.

2.3.3 After 10 minutes was reached, rinse it with deionized water

thoroughly and let dry in air.

2.4 Graphite

Carbon used the Graphite pencil for the electrode (Figure 3-3)

23

Figure 3-1 Diagram Preparation the electrode

Design the PCB

(Printed Circuit Board) for electrode

Cut gold wire, platinum wire, silver

wire and Graphite pencil by 1.5 cm

Cleaning gold wire, platinum wire

and silver wire

Electrode type I: platinum silver gold Electrode

Electrode type II: platinum gold and Graphite

Set gold wire, platinum wire, silver

wire

on the PCB

24

Figure 3-2 A three-electrode was employed for Portable voltammetric device for

detecting heavy metal contamination (cyclic voltammetry)

Figure 3-3 Graphite pencil and Graphite electrode

Part 2 Invent meter, voltmeter ammeter and power supply

2.1 Design and circuit built on a printed circuit board (PCB) for

Portable voltammetric device for detecting heavy metal contamination

(Figure 3-4)

Block a, Variable digital voltage

This circuit can provide currents up to 100mA. The working and circuit is

explained below. Here we are going to take the voltage provided at the OUTPUT

terminal and feed it into one of ADC channels of Arduino. After conversion we are

25

going to take that DIGITAL value and we will relate it to voltage and show the result

in 16*4 display. This value on display represents the variable voltage value.

The UNO ADC is of 10 bit resolution (so the integer values from (0- (2^10)

1023)).This means that it will map input voltages between 0 and 5 volts into integer

values between 0 and 1023. So for every (5/1024= 4.9mV) per unit.

Block b, Negative voltage and OP-Amp inverting

Simple Negative Voltage Converter The majority of applications will

undoubtedly utilize the ICL7660 for generation of negative supply voltages. Figure

below shows typical connections to provide a negative supply for Op-Amp inverting

circuit will make variable negative voltage

Block c, Switching pole circuit

In circuit use transistor make not gate circuit for Switching Positive

voltage and Negative voltage. Programing control at digital output pin

Block d, Current sensor circuit and ADC 16Bit I2C (MCP3425)

Use ic CA3130 This simple micro ampere meter circuit can help in

measuring small currents. The output voltage of the opamp CA3130 is proportional to

the measured current.

By feedback resistors through. Ic MCP3425 convert Analog signals to

Digital signals by I2C for Addition Arduino.

Block e, Microcontroller Arduino uno r3

Arduino Uno r3 is a microcontroller board based on the ATmega 328 P.

Arduino is easy to learn microcomputer system. Many engineering students are using

it in their projects and professionals also. Because it is ready to use board.

Block f, Display LCD 16X4 Module

Display LCD 16X4 Moduleare using a 16×4 Character LCD so we have

4 lines of 16 characters each available.The I2C LCD module is connected to 4 pin. Is

VCC, GND, SDA and SCLfrom the Arduino are connected to the breadboard.

Block g, Micro SD card Module

This is a Micro SD module. It is compatible with SD card (commonly

used in Mobile Phone) which is the most tiny card in the market. SD module has

various applications such as data logger, audio, video, graphics. This module will

greatly expand the capbility an Arduino can do with their poor limited memory.

26

This module has SPI interface and 5V power supply which is compatible with

Arduino UNO/Mega. The Pinout is fully compatible

Figure 3-4 Portable voltammetric device for detecting heavy metal contamination

circuit

2.2 Invent auto variable power supply and voltmeter ammeter keep

data to micro SD

Experiment step for Invent meter, voltmeter ammeter and power supply

(Portable voltammetric device for detecting heavy metal contamination, Figure 3-5)

2.2.1 Make variable power supply circuit 0-5V by Arduino IDE

(microcontroller).

2.2.2 Add A to D 16 bit module 16 Bit Analog to digital with I2c

(MCP3425)

2.2.3 Make negative power supply circuit -5V by IC ICL7660

2.2.4 Make inverting OP-AMP for variable negative power supply

27

2.2.5 Make program control power supply -1.30 V to 1.30 V by

Arduino IDE.

2.2.6 Make program memory value to SD card.

2.2.7 Display value to LCD display.

Figure 3-5 Portable voltammetric device for detecting heavy metal contamination

2.3 Step for program

The step for the program on Portable voltammetric device for detecting

heavy metal contamination (Portable cyclic voltammetry) (Figure 3-6)

2.3.1 Connect USB electrode dip electrode in sample.

2.3.2 Start program to push buttom switch “start”

2.3.3 Voltammetry portable will scan start voltage -1.30 v to 1.3v

2.3.4 About 10 min. keep data into micro SD card and program

display Result heavy metal.

2.3.5 Display value.

2.3.6 End program.

28

Figure 3-6 The step for the program on Portable voltammetric device for detecting

heavy metal contamination

2.4 Program Portable voltammetric device for detecting heavy metal

contamination

(Arduino IDE 1.6.8)

#include <MCP342X.h>

#include <Wire.h>

#include <LiquidCrystal_I2C.h>

#include <SD.h>

29

//MCP3425 I2C address is 0x68 (104)

#define Addr 0x68

LiquidCrystal_I2C lcd (0x3F,16, 4);

const int chipSelect = 2;

int dataString = 0;

//***** parameter voltage******//

int voltageadjust =44; //starting initial variable output

float volts = 0.0;

float Current = 0.0;

float tpb = 0.0;

float tcu = 0.0;

float tcd = 0.0;

//**** parameter voltage loop ******//

int a=0,i=0,j=0;

//***** parameter button switch pin 4 output pin 5 *******//

int buttonPin = 4;

int controlOut = 5;

int ledPin = 6;

int ledState = LOW;

int lastState = HIGH;

int StateOut = HIGH;

void setup ()

{

//Initialise I2C communication as MASTER

Wire.begin ();

//Start serial communication and set baud rate = 9600

Serial.begin (9600);

//Start I2C Transmission

Wire.beginTransmission (Addr);

//Send configuration command

//Continuous conversion mode, 12-bit resolution

Wire.write (0x10);

30

//Stop I2C Transmission

Wire.endTransmission ();

delay (300);

while (!Serial)

{ ; }

Serial.print ("Initializing SD card...");

//make sure that the default chip select pin is set to

//output, even if you don't use it:

pinMode (2, OUTPUT);

//see if the card is present and can be initialized:

if (!SD.begin (chipSelect)) {

Serial.println ("Card failed, or not present");

lcd.print (" Card failed ");

//don't do anything more:

return;

}

Serial.println ("card OK.");

pinMode (3,OUTPUT);//PWM output pin

pinMode (buttonPin,INPUT);//button Start

pinMode (controlOut,OUTPUT);//OUTPUT control PC817

pinMode (ledPin,OUTPUT);

lcd.begin ();//number of characters on LCD

//Print a logo message to the LCD.

lcd.print (" Voltammetry");

lcd.setCursor (0, 1);

delay (2000);

lcd.clear ();

lcd.print ("Volt= ");//printing name

lcd.setCursor (2, 1);

lcd.print ("I = ");//printing name

}

void loop ()

31

{

unsigned int data[2];

//Start I2C Transmission

Wire.beginTransmission (Addr);

//Select data register

Wire.write (0x00);

//Stop I2C Transmission

Wire.endTransmission ();

//Request 2 bytes of data

Wire.requestFrom (Addr, 2);

//Read 2 bytes of data

//raw_adc msb, raw_adc lsb

if (Wire.available () == 2)

{

data[0] = Wire.read ();

data[1] = Wire.read ();

}

//Convert the data to 12-bits

int raw_adc = (data[0] & 0x0F) * 256 + data[1];

if (raw_adc > 2047)

{

raw_adc -= 4096;

}

int buttonState = digitalRead (buttonPin);

if (buttonState == LOW && buttonState!=lastState)

{

if (StateOut==HIGH)

{

StateOut = LOW;

}

else

StateOut = HIGH;

32

}

}

digitalWrite (controlOut,StateOut);

lastState = buttonState;

delay (20);

float VOLTAGEVALUE = (analogRead (A0));//read ADC value at A0

if (ledState==LOW)

{

VOLTAGEVALUE = ((VOLTAGEVALUE*5)/1024);//converting

digital value to voltage

}

else

{

VOLTAGEVALUE = - ((VOLTAGEVALUE*5)/1024);//converting

digital value to voltage

}

float DCvalue = raw_adc;

volts = (DCvalue)-10;

Current = volts;

{

if (StateOut == LOW && dataString<1312)

{

File dataFile = SD.open ("datalog.txt", FILE_WRITE);

dataFile.print (dataString);

dataFile.print ("\t ");

dataFile.print (VOLTAGEVALUE, 4);

dataFile.print ("\t ");

dataFile.println (Current, 4);

dataFile.close ();

//print to the serial port too:

Serial.println (dataString);

dataString++;

33

//delay (30);

}

lcd.setCursor (5, 0);//go to position 9 on LCD

lcd.print (VOLTAGEVALUE);

lcd.setCursor (11, 0);

lcd.print ("V");

lcd.setCursor (-15,5);//go to position 9 on LCD

lcd.print (Current,4);

}

analogWrite (3,voltageadjust);//provide PWM at PIN3

if (StateOut == LOW)

{

if (i<65)

{

Serial.print ("Step No:")

Serial.println (i);

Serial.print ("AIN0: ");

Serial.print (analogRead (A0));

Serial.print (" \tVoltage: ");

Serial.print (VOLTAGEVALUE, 4);

Serial.print ("V");

Serial.print ("\tCurrent: ");

Serial.print (Current, 4);

Serial.println ("uA");

delay (300);

voltageadjust++;

i++;

//delay (300);

}

else if (j<65)

{

Serial.print ("Step No:")

34

Serial.println (j);

Serial.print ("AIN0: ");

Serial.print (analogRead (A0));

Serial.print (" \tVoltage: ");

Serial.print (VOLTAGEVALUE, 4);

Serial.print ("V");

Serial.print ("\tCurrent: ");

Serial.print (Current, 4);

Serial.println ("uA");

delay (300);

voltageadjust--;

j++;

//delay (3000);

// Serial.println ("********");

}

else if (a<9)

{

Serial.println ("--------------");

Serial.print ("a=");

Serial.println (a);

i=0;j=0;

//a++;

if (a>=0)

{

if (ledState == LOW)

{

ledState = HIGH;

}

else

{

ledState = LOW;

}

35

digitalWrite (ledPin,ledState)

}

a++;

}

if (a==9 && j==65)

{

lcd.clear ();

lcd.print ("Cyclic = 5 turn");

delay (1500);

}

}

delay (20);

}

********* END PROGRAM *********

Part 3 Comparison of the electrode efficiency in blank and standard

solution

Comparison of the electrode efficiency. (Electrode type I: platinum wire, silver wire,

gold wire and Electrode type II: platinum wire, silver wire, graphite pencil) for

detecting lead (Pb) cadmium (Cd) and copper (Cu)

Step for study electrode efficiency

1. Calibration Standard curve from stock standard solution of lead (Pb),

cadmium (Cd) and copper (Cu)

2. Testing electrode on standard solution of lead (Pb), cadmium (Cd) and

copper (Cu)

3. Testing electrode on mix standard solution of lead (Pb), cadmium (Cd)

and copper (Cu) (Figure 3-7)

4. Voltage -1.3 to 1.3 V

5. Record for current and Successive cyclic voltammograms

36

Figure 3-7 Show electrode testing on mix standard solution of lead (Pb), cadmium

(Cd) and copper (Cu)

Part 4 Testing for detect heavy metal in standard solution and water

sample

The experimental and analytical

1. Study Effect of the supporting electrolyte, pH and Successive cyclic

voltamogrames. Preparation the electrolyte used acetate buffer for testing (Table 3-3)

Table 3-3 Acetate buffer for supporting electrolyte (p H)

Acetate buffer (p H)

3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5

R1 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5

R2 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5

R3 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5

37

2. Comparative study of the performance of the electrode

Comparative study of the performance of the electrode between gold wire,

silver wire, platinum wire and graphite electrode by good supporting electrolyte in 1

(Table 3-4)

Table 3-4 Concentration of standard solution

Standard solution (µg L-1)

add Acetate buffer (p H)

10 20 30 40 50 60 70 80 90 100

R1 10 20 30 40 50 60 70 80 90 100

R2 10 20 30 40 50 60 70 80 90 100

R3 10 20 30 40 50 60 70 80 90 100

3. Linearity

Prepared at six concentrations of standard solutions. Five replicates at each

concentration will be analyzed. (Table 3-5)

Table 3-5 concentrations of standard solutions (Pb, Cd and Cu) for calibration curve

Concentration (µg L-1

) of standard solution (Pb, Cd and Cu)

add acetate buffer p H 5.5

replication 10

20 30 40 50 100

Blank DI DI DI DI DI DI

R1 10 20 30 40 50 100

R2 10 20 30 40 50 100

R3 10 20 30 40 50 100

R4 10 20 30 40 50 100

R5 10 20 30 40 50 100

Test electrode in sample with Cyclic voltammetry and slope of the

calibration curve with current (I), µA on Axis y and concentrations of standard

38

solutions, µg L-1

on Axis X, for the linearity

Part 4 Testing for detect heavy metal in standard solution and sample water

To use the Portable voltammetric device for detecting heavy metal

contamination in sample water.

1. Preparation of water sample form tap water 5 sample (The water sample

collect form Chonburi province.)

2. Testing for detect heavy metal in sample water by the Portable

voltammetric device for detecting heavy metal contamination.

3. Comparison the study form Portable voltammetric device for detecting

heavy metal contamination and the result form graphite furnace atomic absorption

spectrometer (GFAAS), (GFAAS at Institute of Marine Science, Burapha University)

and limit detection for heavy metal show in Table 3-6

Table 3-6 Limit detection of heavy metal by GFAAS

heavy metal Limit detection (µgL-1

)

Pb 0.03

Cd 0.02

Cu 0.04

Procedure for GFAAS

1. Pipet DI water and sample (water sample) 10 ml in beaker

2. Add 0.05 ml HNO3 65% (w/w) digest on hot plate (in incubator) about 5 min.

3. Analysis blank (DI water) and sample with GFAAS

4. Calculation Pb, Cd and Cu

Calculation and expression of result

C = (C0 – CB) X F

When C = Concentration Pb, Cd and Cu in sample (mg/L)

C0 = Concentration Pb, Cd and Cu in solution sample (mg/L)

CB = Concentration Pb, Cd and Cu in methode blank (mg/L)

F = dilution factor

* Analysis blank before analyst sample or analyst standard solution

39

CHAPTER 4

RESULTS

In chapter 3, the experiments were designed to achieve the research

objectives mentioned in chapter 1. This research aims to an alternative voltammetric

procedure for the simultaneous determination of lead (Pb), cadmium (Cd) and copper

(Cu) were developed by using microcontroller for inventing portable voltammetry.

The experimental and analytical results are presented in this chapter.

1. Effect of the supporting electrolyte, pH and Successive cyclic

voltamogrames

Influence of pH on the cyclic voltammogrames for 100 µgL-1

of Cd Pb and

Cu at The portable voltammetric device in buffer solution. The influence of pH on the

peak current of Cd Pb and Cu was studied in the pH range of 3.5 to 7.5 The results

obtained show that the oxidation peak current increased with increased in pH from 3.5

to 7.5; however, the currents decreased when the pH further increased from 3.5 to 7.5.

The decrease in peak current at higher pH values could be due to the formation of lead

(Pb), cadmium (Cd) and copper (Cu). Among the various electrolytes (such as acetate

buffer).The best results were obtained in acetate buffer media. Thus an electrode

voltammetry of pH 5.5 was adopted as support electrolyte in the further studies.

(Figure 4-1)

40

(a)

(b)

41

(c)

Figure 4-1 Successive cyclic voltammograms of Lead (Pb) in acetate buffer

(a) pH 3.5 (b) pH 5.5 and (c) pH 7.5

2. The electrode

Comparative study of the performance of the electrode between gold wire,

silver wire, platinum wire and graphite electrode by good supporting electrolyte

2.1 Compare gold wire, platinum and silver wire for working electrode

In 20 µg L-1

of standard solution of Pb, Cd and Cu we used the electrode

Working Electrode (WE) used silver wire, Reference Electrode (RE) used platinum

wire and Counter Electrode (CE) used silver wire electrode compare Working

Electrode (WE) used gold wire, Reference Electrode (RE) used silver wire and

Counter Electrode (CE) used platinum wire electrode and Working Electrode (WE)

used gold wire, Reference Electrode (RE) used platinum wire and Counter Electrode

(CE) used silver wire electrode (Figure 4-2)

42

(a)

(b)

43

(c)

Figure 4-2 Successive cyclic voltammograms of Lead (Pb) on gold wire silver wire

and platinum wire electrode (a) gold wire (b) silver and (c) platinum wire

2.1 Compare gold wire electrode and graphite pencil electrode in DI

water and Standard solution 100 µgL-1

the result show successive cyclic

voltammograms (Figure 4-3)

(a)

44

(b)

(c)

45

(d)

Figure 4-3 Successive cyclic voltammograms of Graphite pencil electrode (a) DI

water (b) Lead (Pb) (c) cadmium (Cd) and (d) Copper (Cu)

3. Analytical characteristics and Electrochemical behavior of the

electrode voltammetry

The cyclic voltammetric was employed to investigate the electrochemical

behavior on the gold wire silver wire and platinum wire electrode in 5.5 electrolyte

(Figure 4-4)

Illustrates the responses obtained by cyclic voltammetry between -1.30 V to

1.30 V at gold electrode.

46

(a)

(b)

47

(c)

(d)

Figure 4-4 Successive cyclic voltammograms (a) Deionized water (b) Lead

(II) 20 µg L-1

(c) Cadmium (II) 20 µg L-1

and (d) Copper (II) 20µg L-1

48

4. The portable voltammetric device for detecting heavy metal

contamination in standard solution and sample water

Successive cyclic voltammograms of following the potentionstatic recored at

room temperature. The electrode that used gold wire, silver wire and platinum wire

for working electrode, counter electrode and reference electrode respectively. The

electrode can be easily prepared and showed a good analytical response was linear in

the range of 10 µg L-1 to 50 µg L-1. Successive cyclic voltammograms of gold

electrode and scan start voltage -1.30 v to 1.3v at room temperature. The portable

voltammetric device for detecting Lead (Pb) cadmium (Cd) and copper (Cu)

contamination. (Figure 4-5)

(a)

49

(b)

(c)

Figure 4-5 Successive cyclic voltammograms (a) Lead (II) 10-50 µgL-1

(b)

Cadmium (II) 10-50 µgL-1

and (c) Copper (II) 10-50 µgL-1

5. Linearity

Form the linearity between the metal concentration and the peak current, we

can estimate the detection sensitivity of the electrode.

The metal concentration deposited on the gold electrode increases with an

increasing accumulation time. Therefore, as the accumulation time increases, the peak

50

current is enhanced, which leads to an increase in the slope of the linear relationship

between the peak current is significantly influenced by the portable voltammetric

device for detecting heavy metal contamination and show the peak current against the

Cd Pb and Cu concentrations. (Figure 4-6)

(a)

(b)

51

(c)

(d)

Figure 4-6 Dependency of the peak current on the concentration of (a) Lead (II)

10-50 µgL-1

(b) Cadmium (II) 10-50 µgL-1

and (c) Copper (II) 10-50 µgL-1

52

6. Analysis of sample water

In order to find out the applicability of gold wire, platinum wire and silver

wire electrode detecting as well as the validity of the developed procedure, the

electrode was utilized to detect trace amounts of Cd Pb and Cu in standard solution

and five water sample. The sample water was collected form Chonburi province. The

result shows the analytical characteristics and successive cyclic voltammograms in

Figure 4-7

(a)

(b)

53

(c)

(d)

54

(e)

Figure 4-7 The results for the simultaneous detection of lead (Pb) cadmium (Cd) and

copper (Cu) in 5 sample water (a) sample water number 1 (b) sample water

number 2 (c) sample water number 3 (d) sample water number 4 (e)

sample water number 5

55

CHAPTER 5

DISCUSSION AND CONCLUSION

In this chapter, the results in chapter 4 were discussed, and conclusions are

presented as the followings.

Discussions

Preliminary studies

The portable voltammetric device for detecting heavy metal contamination have been

prepared through electrode method in acetate buffer solution, p H 5.5

The results in Figure 4-1 show effect of the supporting electrolyte, pH and

Successive cyclic voltamogrames in acetate buffer media, p H 5.5 successive cyclic

voltammograms of lead (Pb) and high current 200-250 µA on 100 µgL-1

of Lead (Pb).

The results of the determination of Pb, Cd and Cu in Standard solution

sample and sample water in Figure 4-2 Show successive cyclic voltammograms of

Lead (Pb) on gold wire, silver wire and platinum wire electrode, The performance of

the electrode gold wire, silver wire, platinum wire is working electrode, reference

electrode and counter electrode respectively. The Figure 4-3 show graphite pencil

electrode for working electrode and successive cyclic voltammograms on DI water

standard solution of Lead (Pb) cadmium (Cd) and Copper (Cu) but all results show

the detecting low current than gold wire electrode at the same concentration.

The results in Figure 4-4 Analytical characteristics and Electrochemical

behavior of the electrode voltammetry. The cyclic voltammetric was employed to

investigate the electrochemical behavior on the gold wire silver wire and platinum

wire electrode in 5.5 electrolyte. Illustrates the responses obtained by cyclic

voltammetry between -1.30 V to 1.30 V at gold electrode. Show successive cyclic

voltammograms Deionized water show detecting current at -10 to 10 µA, -60 to 20

µA for Lead (II) 20µg L-1

, - 70 to 20 µA for Cadmium (II) 20µg L-1

and -130 to 20

µA for Copper (II) 20µg L-1

.

The results in Figure 4-5 show the portable voltammetric device for

detecting heavy metal contamination in standard solution and sample water.

56

Successive cyclic voltammograms of following the potentionstatic recorded at room

temperature. The electrode that used gold wire, silver wire and platinum wire for

working electrode, counter electrode and reference electrode respectively. The

electrode can be easily prepared and showed a good analytical response was linear in

the range of 10 µg L-1

to 50 µg L-1

. Successive cyclic voltammograms of gold

electrode and scan start voltage -1.30 v to 1.3v at room temperature. The portable

voltammetric device for detecting Lead (Pb) -40 to 20 µA, -50 to 20 µA, -65 to 20 µA

and -70 to 20 µA cadmium (Cd) -60 to 20 µA, -80 to 20 µA,-90 to 20 µA and -110 to

20 µA and copper (Cu) -90 to 20 µA, -110 to 20 µA,-150 to 20 µA and -180 to 20 µA

contamination at 10, 20, 30 and 50 µgL-1

of lead (Pb), cadmium (Cd) and copper

(Cu), respectively.

The results of Linearity, Form the linearity between the metal concentration

and the peak current, we can estimate the detection sensitivity of the electrode. The

metal concentration deposited on the gold electrode increases with an increasing

accumulation time. Therefore, as the accumulation time increases, the peak current is

enhanced, which leads to an increase in the slope of the linear relationship between

the peak current is significantly influenced by the portable voltammetric device for

detecting heavy metal contamination and show the peak current against the Cd Pb and

Cu concentrations.

The results in Figure 4-6 shows the peak current of Pb Cd and Cu

concentration, respectively. The slopes of the linearity were determined to be Lead

(Pb) y = -10.4x -35, R2 = 0.9555, cadmium (Cd) y = -16x -47.5, R

2 = 0.9405 and

copper (Cu) y = -32.3x -52, R2 = 0.9834

The results in Figure 4-7 shows analysis of sample water. In order to find

out the applicability of gold wire, platinum wire and silver wire electrode detecting as

well as the validity of the developed procedure, the electrode was utilized to detect

trace amounts of Cd Pb and Cu in standard solution and five water sample. The

sample water was collected form Chonburi province. The result shows the analytical

characteristics and successive cyclic voltammograms found heavy metal in sample

water 4 sample form 5 sample. The cyclic voltammograms in sample number 1 show

not detected, cyclic show current -6 to 12 µA. The cyclic voltammograms in sample

number 2 cyclic voltammogrames show current -42 to 20 µA. The cyclic

57

voltammograms in sample number 3 cyclic voltammogrames show current -50 to 40

µA. The cyclic voltammograms in sample number 4 cyclic voltammogrames show

current -55 to 20 µA. The cyclic voltammograms in sample number 5 cyclic

voltammogrames show current -85 to 20 µA. Finally, the same found form GFAAS,

found heave metal in 4 sample water form 5 sample water.

Conclusion

In this study, we demonstrated the portable voltammetry that used gold wire,

platinum wire and silver wire for working electrode, reference electrode and counter

electrode respectively. The electrode can be easily prepared and showed a good

analytical response for lead (Pb), Cadmium (Cd) and copper (Cu) in standard solution

and tap water. The portable heavy metal meter is easily taken, used and low cost,

which is a feature useful for monitoring the lead (Pb), Cadmium (Cd) and copper (Cu)

in sample water, tap water, waste water and drinking water.

In addition to its simplicity, low cost, low reagent consumption and

reusability, the gold wire, platinum wire, silver wire and graphite pencil electrode can

also be used with advantage for detecting other metal toxic ions in natural water

samples.

58

REFERENCES

Anandhakumar, S., & Mathiyarasu, J. (2012). In situ bismuth film modified carbon

fiber microelectrode for nanomolar detection of cadmium and lead.

Indian journal of chemistry, 51A, 699-703.

Arpadjan, S., Celik, G., Taskesen, S., & Gucer, S. (2008). Arsenic, cadmium and lead

in medicinal herbs and their fractionation. Food and Chemical Toxicology

46, 2871-2875.

Birinci, A., Eren, H., Coldur, F., Coskun, E., & Andac, M. (2016). Rapid

determination of trace level copper in tea infusion samples by solid contact

ion selective electrode. Food and drug analysis, Article in press

Dasbas, T., Sacmac, S., Ulgen, A., & Kartalb, S. (2015). A solid phase extraction

procedure for the determination of Cd (II) and Pb (II) ions in food and water

samples by flame atomic absorption spectrometry. Food Chemistry, 174,

591-596.

Desideri, D., Meli, M. A., Roselli, C., & Feduzi, L. (2011). Polarized X ray

fluorescence spectrometer (EDPXRF) for the determination of essential and

non essential elements in tea. Microchemical Journal, 98(2), 186-189.

Duran, C., Ozdes, D., Sahin, D., Bulut, V. N., Gundogdu, A., & Soylak, M. (2011).

Preconcentration of Cd (II) and Cu (II) ions by coprecipitation without any

carrier element in some food and water samples. Microchemical Journal,

98(2), 317-322.

Grzesik, E. B., & Kolon, A. J. (2008). Leaching of cadmium and lead from dried

fruits and fruit teas to infusions and decoctions. Food Composition and

Analysis Journal, 21, 326-331.

Gorur, F. K., Keser, R., Akcay, N., Dizman, S., & Okumusoglu, N. T. (2011).

Radionuclides and heavy metals concentrations in Turkish market tea.

Food control, 22(12), 2065-2070.

59

Guo, J., Chai, Y., Yuan, R., Song, Z., & Zou, Z. (2011). Lead (II) carbon paste

electrode based on derivatized multi-walled carbon nanotubes: Application

to lead content determination in environmental samples. Sensors and

Actuators B, 155, 639-645.

Hevia, K., Arancibia, V., & Romo, C.R. (2015). Levels of copper in sweeteners,

sugar, tea, coffee and mate infusions. Determination by adsorptive stripping

voltammetry in the presence of α-lipoic acid. Microchemical Journal, 119,

11-16.

Hwang, G. H., Han, W. K., Park, J. S., & Kang, S. G. (2008). Determination of trace

metals by anodic stripping voltammetry using a bismuth-modified carbon

nanotube electrode. Talanta ,76(2), 301-308.

Injanga, U., Noyroda, P., Siangprohb, W., Dungchaia, W., Motomizuc, S., &

Chailapakulad, O. (2010). Determination of trace heavy metals in herbs by

sequential injection analysis-anodic stripping voltammetry using screen-

printed carbonnanotubes electrodes. Analytica Chimica Acta, 668, 54-60.

Jothimuthu, P., Wison, R. A., Herren, J., Pei, X., Kang, W., Daniels, R., Wong, H.,

Beyette, F., Heineman, W. R., & Papautsky, I. (2013). Zinc detection in

Serum by Anodic stripping voltammetry on microfabricated bismuth

electrode. Electroanalysis, 25(2).

Karimi, G., Hasanzadeh, M. K., Nili, A., Khashayarmanesh, Z., Samiei, Z., Nazari,

F., & Teimuri, M. (2008). Concentrations and Health Risk of Heavy Metals

in Tea Samples Marketed in IRAN. Pharmacologyonline, 3, 164-174.

Kefala, G., Economou, A., Voulgaropoulos, A., & Sofoniou, M. (2003). A study of

bismuth-film electrodes for the detection of trace metals by anodic stripping

voltammetry and their application to the determination of Pb and Zn in

tapwater and human hair. Talanta, 61, 603-610.

Krolicka, A., Pauliukait, R., Svancara, I., Metelkac, R., Bobrowskia,A., Norkusb, A.,

Kalcherd, K., & Vytřas, K. (2002). Bismuth-film-plated carbon paste

electrodes. Electrochemistry Communications, 4, 193-196.

60

Liu, G. L.,Wang, J. F., Li, Z. Y., Liang, S. Z., Liu, J. H., &Wang, X. N. (2009).

Development of direct competitive enzyme-linked immunosorbent assay for

the determination cadmium residue in farm produce. Applied Biochemistry

and Biotechnology, 159(3), 708-717.

Milania, R. F., Morganoa, M. A., & Cadoreb, C. (2016). Trace elements in Camellia

sinensis marketed in southeastern Brazil: Extraction from tea leaves to

beverages and dietary exposure. LWT-Food Science and Technology,

68, 491-498.

Malik, J., Frankova, A., Drabek, O., Szakova, J., Asha, C., & Kokoska, L. (2013).

Aluminium and other elements in selected herbal tea plant species and their

infusions. Food Chemistry, 139, 728-734.

Ning, P. B., Gong, C. M., Zhang, Y. M., Guo, K. K., & Bai, J. A. (2011). Lead,

cadmium, arsenic, mercury and copper levels in Chinese Yunnan Pu'er tea.

Food Additives & Contaminants. Part B, Surveillance, 4(1), 28-33.

Raj, J., Raina, A. M., & Dogra, T. D. (2013). Direct Determination of Zinc,

Cadmium, Lead, Copper Metal in Tap Water of Delhi (India) by Anodic

Stripping Voltammetry Technique. EDP Sciences.

Rehacek, V., Hotovy, I., Vojs, M., & Mika, I. (2008). Bismuth film electrodes for

heavy metals determination. Microsyst Technol, 14, 491-498.

Rubio, C., Lucas, J. R. D., Gutiérrez, A. J., Glez-Weller, D., Pérez Marrero, B.,

Caballero, J. M., Revert, C. A., & Hardisson. (2012). Evaluation of metal

concentrations in mentha herbal teas (Mentha piperita, Mentha pulegium and

Mentha species) by inductively coupled plasma Spectrometry.

Pharmaceutical and Biomedical Analysis Journal, 71, 11-17.

Salih, F.E., Ouarzane, A., & Rhazi, M.E. (2015). Electrochemical detection of lead

(II) at bismuth/Poly (1,8-diaminonaphthalene) modified carbon paste

electrode. Arabian Journal of Chemistry, 11, 12-19.

Seenivasan, S., Manikandan, N., Muraleedharan, N. N., & Selvasundaram, R. (2008).

Heavy metal content of black teas from south India. Food Control, 19,

746-749.

Solidum, J. N. (2014). Lead Levels in Fresh Medicinal Herbs and Commercial Tea

Products from Manila, Philippines. APCBEE Procedia, 10, 281-285.

61

Soylak, M., Tuzen, M., Mendil, D., & Turkekul, I. (2006). Biosorption of heavy

metals on Aspergillus fumigatus immobilized Diaion HP-2MG resin for

their atomic absorption spectrometric determinations. Talanta, 70(5),

1129-1135.

Tarleya, C.R.T., Santosa, V.S., Baêtaa, B.E.L., Pereirab, A.C., & Kubota, L.T.

(2009). Simultaneous determination of zinc, cadmium and lead in

environmental water samples by potentiometric stripping analysis (PSA)

using multiwalled carbon nanotube electrode. Hazardous Materials, 169,

256-262.

Tokahoglu, S., & Kartal, S. (2004). Bioavailability of soil-extractable metals to tea

plant by BCR sequential extraction procedure. Instrumentation Science and

Technology, 32(4), 387-400.

Tufa, L.T., Sirajz, K., & Soreta, T. R. (2013). Electrochemical Determination of Lead

Using Bismuth Modified Glassy Carbon Electrode. Russian Journal of

Electrochemistry, 49(1), 59-66.

Tuzen, M., Soylak, M., & Elci, L. (2005). Multi-element pre-concentration of heavy

metal ions by solid phase extraction on Chromosorb 108. Analytica Chimica

Acta, 548(1-2), 101-108.

Wan,W., Sun, Q., Li, H., Sun, F., Hu, N., & Wang, P. (2015). Screen-printed gold

electrode with gold nanoparticles modificationfor simultaneous

electrochemical determination of lead and copper. Sensors and Actuators B,

209, 336-342.

Wang, Z., Wang, H., Zhang, Z., & Liu, G. (2014). Electrochemical determination of

lead and cadmium in rice by adisposable bismuth/electrochemically reduced

graphene/ionic liquidcomposite modified screen-printed electrode. Sensors

and Actuators B, 199, 7-14.

Zhong, W., Ren, T., & Zhao, L. (2016). Determination of Pb (Lead), Cd (Cadmium),

Cr (Chromium), Cu (Copper), and Ni (Nickel) in Chinese tea with

high-resolution continuum source graphite furnace atomic absorption

spectrometry. Food and drug Analysis, 46-55.

62

APPENDIX

63

APPENDIX A

Supplement data for figures

64

Table A-1 Analysis of Copper (Cu)

Copper (Cu)

Voltage:

V

Current: µA

100 µg/L 50 µg/L 40 µg/L 30 µg/L 20 µg/L 10 µg/L

0 76 5

5 47 3

0 50 70 59 36 11 15

0.0049 36 50 44 28 9 12

0 28 42 37 23 9 12

0.0195 24 35 31 21 9 10

0.0391 24 31 25 18 8 8

0.0488 22 25 23 17 7 11

0.0586 22 25 22 15 8 7

0.0732 22 20 21 12 8 10

0.083 22 20 15 13 7 7

0.0879 22 18 18 10 7 9

0.1074 19 20 14 11 9 9

0.1318 18 14 12 9 7 9

0.1367 21 14 12 12 7 5

0.1514 18 12 11 11 5 7

0.1709 15 13 13 8 9 11

0.1904 16 11 10 13 6 6

0.1904 16 13 12 11 3 7

0.2148 13 12 9 10 11 8

0.2393 15 13 11 13 10 7

0.2490 13 13 11 10 8 6

0.2588 16 10 13 11 13 7

0.2783 15 13 15 8 10 9

0.3027 13 10 12 8 10 7

0.3271 16 14 15 11 12 9

0.3418 15 11 15 15 14 10

65

Table A-1 (Continued)

Copper (Cu)

Voltage:

V

Current: µA

100 µg/L 50 µg/L 40 µg/L 30 µg/L 20 µg/L 10 µg/L

0.3613 17 11 15 13 10 9

0.3809 19 13 15 10 15 9

0.3857 18 13 16 15 15 9

0.4004 20 15 17 15 13 8

0.4199 20 15 18 15 15 12

0.4297 23 15 19 13 13 12

0.4688 24 18 16 17 14 15

0.4834 23 15 17 15 16 12

0.4883 26 17 21 15 14 11

0.5273 30 16 20 17 14 15

0.5518 29 17 18 20 19 8

0.5713 30 17 20 18 17 14

0.5859 28 17 21 18 18 13

0.6055 31 17 22 17 16 10

0.6494 32 16 25 17 21 18

0.6787 33 19 24 17 22 14

0.6396 30 21 20 20 16 17

0.6885 33 18 23 21 17 14

0.7275 34 21 25 20 20 20

0.7520 35 18 21 19 21 16

0.7959 39 21 22 22 20 17

0.7910 35 21 24 23 23 14

0.8154 36 18 28 22 20 19

0.8447 33 18 25 19 21 18

0.8740 34 24 28 22 20 16

0.8887 36 22 26 24 24 19

66

Table A-1 (Continued)

Copper (Cu)

Voltage:

V

Current: µA

100 µg/L 50 µg/L 40 µg/L 30 µg/L 20 µg/L 10 µg/L

0.9277 39 20 29 26 23 16

0.9570 40 22 27 24 24 19

0.9814 35 24 32 23 21 21

0.9961 35 27 33 26 23 20

1.0352 40 24 32 23 29 22

1.0547 41 27 31 29 30 22

1.1084 40 28 35 24 32 22

1.1230 36 31 32 26 31 24

1.1475 39 29 34 28 38 25

1.1914 39 26 36 31 36 25

1.2305 47 29 35 36 36 29

1.2891 45 32 33 35 36 24

1.2939 50 36 36 33 42 30

1.3184 53 38 44 35 35 35

1.2793 36 36 36 34 25 28

1.2500 31 32 31 26 23 25

1.2305 28 25 23 22 18 22

1.2012 25 20 24 22 19 18

1.1426 21 21 19 16 18 15

1.1279 18 21 18 15 11 12

1.0889 17 17 18 13 14 14

1.0547 16 12 12 14 9 10

1.0400 15 13 14 12 12 13

1.0205 14 12 15 13 13 13

0.9863 16 11 13 12 9 12

0.9570 16 9 12 8 9 12

67

Table A-1 (Continued)

Copper (Cu)

Voltage:

V

Current: µA

100 µg/L 50 µg/L 40 µg/L 30 µg/L 20 µg/L 10 µg/L

0.9326 11 12 13 8 11 7

0.8984 9 9 10 7 7 11

0.8789 11 12 8 7 6 7

0.8496 8 7 10 11 9 7

0.8252 9 7 12 9 5 8

0.8105 9 8 6 8 6 7

0.7813 7 7 7 6 7 7

0.7520 7 8 8 7 3 6

0.7129 6 7 5 5 2 5

0.7080 4 6 7 9 7 7

0.6787 2 7 3 3 4 7

0.6787 2 6 6 2 4 1

0.6299 2 6 5 7 -1 3

0.6201 0 7 4 4 -1 4

0.5957 2 6 5 2 3 4

0.5713 2 8 3 4 0 0

0.5127 2 6 4 2 -3 3

0.5322 -2 6 4 0 -2 0

0.5029 1 4 4 2 2 1

0.4736 2 4 4 1 2 2

0.4785 -2 5 3 2 0 1

0.4395 1 5 2 -1 -2 1

0.4248 -1 3 1 1 -2 0

0.4102 -1 4 0 -2 1 1

0.3906 0 2 1 1 -4 0

0.3857 0 -1 1 1 -1 1

68

Table A-1 (Continued)

Copper (Cu)

Voltage:

V

Current: µA

100 µg/L 50 µg/L 40 µg/L 30 µg/L 20 µg/L 10 µg/L

0.3516 -1 1 3 2 3 0

0.3467 0 2 2 4 2 1

0.3271 0 0 0 -3 1 2

0.3027 -1 0 4 -1 2 1

0.3076 -1 1 0 1 -5 -1

0.2588 1 0 2 1 -3 1

0.2539 -1 4 -1 0 -1 0

0.2295 -1 -2 2 -2 2 1

0.2246 2 -3 0 2 -1 2

0.2490 0 1 -3 0 -2 2

0.1904 -1 -1 -1 -1 1 0

0.1562 0 0 -2 -1 2 2

0.1562 2 2 0 2 -4 3

0.1416 -1 2 -1 -2 -1 3

0.1318 0 -1 0 2 1 0

0.1172 -1 1 0 0 -1 0

0.0977 1 3 -1 -1 0 2

0.0879 -1 -1 0 0 0 3

0.0635 -1 -1 1 -1 -1 1

0.0635 0 3 -2 0 0 0

0.0537 1 -2 -1 1 -2 -2

0.0342 0 -2 -2 1 2 3

0 -1 1 0 1 1 3

0.0146 0 0 1 0 -1 -2

0.0098 0 0 2 1 1 0

0 -2 0 -1 2 -28 -1

69

Table A-1 (Continued)

Copper (Cu)

Voltage:

V

Current: µA

100 µg/L 50 µg/L 40 µg/L 30 µg/L 20 µg/L 10 µg/L

0 -87 0 -17 -7 -8 -5

0 -19 -8 -6 0 -6 1

-0.0098 -14 -3 -3 0 -3 -2

-0.0098 -10 0 -4 -1 -4 0

-0.0293 -10 1 -5 0 -6 -1

-0.0342 -8 -1 0 -1 -3 -2

-0.0342 -5 -2 -4 0 -2 -1

-0.0586 -6 -2 -3 -2 -6 -1

-0.0439 -6 0 -1 -2 -5 -1

-0.0732 -8 -4 -2 -3 -3 -3

-0.0830 -7 -3 -3 -5 -1 0

-0.0879 -6 -1 -2 -5 -2 0

-0.1074 -6 -2 -4 -4 -2 -4

-0.1318 -9 -6 -5 -5 -1 -1

-0.1367 -9 -5 -7 -4 -3 0

-0.1611 -11 -5 -5 -6 -6 -1

-0.1709 -9 -5 -6 -5 -7 -4

-0.1758 -10 -8 -9 -5 -11 -3

-0.2393 -10 -4 -11 -6 -8 -3

-0.1709 -8 -6 -10 -8 -9 -6

-0.2393 -11 -7 -9 -8 -10 -4

-0.2539 -13 -8 -11 -10 -8 -3

-0.2588 -12 -10 -10 -11 -9 -6

-0.2734 -15 -9 -14 -10 -13 -6

-0.3027 -15 -10 -13 -13 -12 -8

-0.3076 -13 -11 -14 -12 -13 -5

70

Table A-1 (Continued)

Copper (Cu)

Voltage:

V

Current: µA

100 µg/L 50 µg/L 40 µg/L 30 µg/L 20 µg/L 10 µg/L

-0.3320 -16 -12 -11 -12 -12 -7

-0.3662 -16 -15 -18 -13 -12 -10

-0.3662 -18 -14 -19 -16 -12 -8

-0.3906 -21 -16 -20 -13 -12 -9

-0.4102 -21 -15 -18 -18 -17 -11

-0.4248 -20 -16 -18 -18 -16 -12

-0.4443 -21 -15 -21 -18 -20 -10

-0.4736 -24 -17 -24 -18 -18 -8

-0.5225 -22 -22 -21 -19 -23 -12

-0.5176 -26 -22 -26 -20 -18 -13

-0.5273 -27 -25 -29 -21 -22 -14

-0.5957 -30 -26 -32 -22 -22 -15

-0.5615 -32 -27 -29 -25 -27 -16

-0.5957 -37 -27 -32 -25 -28 -17

-0.6006 -39 -29 -39 -29 -28 -17

-0.6299 -48 -32 -40 -29 -25 -16

-0.7080 -60 -34 -43 -35 -27 -23

-0.6738 -75 -38 -43 -35 -29 -24

-0.6982 -89 -39 -43 -34 -29 -27

-0.7373 -99 -45 -51 -43 -34 -24

-0.7422 -116 -45 -56 -43 -37 -29

-0.7715 -138 -52 -59 -49 -40 -30

-0.8154 -158 -53 -65 -54 -41 -34

-0.8252 -178 -60 -70 -56 -48 -36

-0.8398 -200 -66 -74 -60 -49 -42

-0.8691 -229 -68 -76 -62 -55 -43

71

Table A-1 (Continued)

Copper (Cu)

Voltage:

V

Current: µA

100 µg/L 50 µg/L 40 µg/L 30 µg/L 20 µg/L 10 µg/L

-0.8936 -263 -71 -85 -66 -54 -44

-0.9277 -298 -76 -89 -66 -63 -44

-0.9619 -347 -82 -91 -76 -62 -51

-0.9863 -417 -84 -96 -74 -67 -53

-1.0498 -479 -89 -101 -85 -72 -53

-1.0400 -533 -96 -109 -88 -72 -59

-1.0596 -601 -96 -116 -96 -81 -60

-1.0937 -671 -110 -118 -99 -80 -67

-1.1328 -757 -110 -125 -99 -89 -69

-1.1426 -830 -119 -133 -110 -93 -75

-1.1914 -891 -122 -140 -113 -91 -75

-1.2402 -932 -132 -148 -122 -100 -83

-1.2500 -954 -134 -155 -129 -103 -84

-1.2842 -963 -150 -152 -135 -109 -88

-1.3281 -969 -165 -162 -153 -91 -95

-1.2695 -964 -181 -153 -123 -79 -82

-1.2549 -961 -156 -137 -106 -74 -72

-1.2158 -946 -134 -121 -102 -63 -65

-1.1768 -914 -109 -104 -81 -58 -56

-1.1426 -867 -101 -93 -77 -49 -52

-1.1133 -807 -85 -84 -65 -41 -42

-1.0937 -738 -78 -75 -59 -42 -42

-1.0547 -661 -71 -65 -54 -37 -39

-1.0547 -592 -62 -59 -46 -34 -31

-0.9766 -528 -54 -51 -42 -29 -32

-0.9717 -471 -47 -46 -36 -24 -27

72

Table A-1 (Continued)

Copper (Cu)

Voltage:

V

Current: µA

100 µg/L 50 µg/L 40 µg/L 30 µg/L 20 µg/L 10 µg/L

-0.9521 -418 -47 -36 -35 -27 -30

-0.9229 -369 -40 -37 -30 -28 -21

-0.9082 -324 -38 -30 -27 -21 -23

-0.8936 -284 -32 -31 -27 -18 -19

-0.8203 -241 -30 -26 -21 -19 -19

-0.8154 -206 -28 -24 -25 -21 -18

-0.7910 -183 -28 -23 -21 -18 -21

-0.7813 -153 -28 -23 -17 -13 -14

-0.7422 -132 -23 -27 -21 -14 -14

-0.7324 -116 -20 -21 -16 -15 -11

-0.6982 -99 -19 -23 -15 -15 -12

-0.6787 -91 -21 -16 -16 -14 -9

-0.6641 -83 -18 -15 -15 -7 -15

-0.6299 -72 -15 -14 -9 -10 -9

-0.6152 -63 -16 -15 -12 -5 -7

-0.5859 -53 -25 -14 -8 -10 -7

-0.5713 -46 -22 -10 -8 -3 -12

-0.5420 -33 -21 -8 -9 -5 -8

-0.5371 -25 -21 -8 -6 -3 -4

-0.5029 -18 -24 -8 -7 -2 -7

-0.5029 -14 -19 -7 -5 -4 -4

-0.4541 -5 -14 -4 -4 1 -4

-0.4395 -3 -10 -3 -2 2 0

-0.4297 1 -11 -1 0 -2 -2

-0.4102 3 -5 -1 1 2 1

-0.3857 2 -3 3 4 1 1

73

Table A-1 (Continued)

Copper (Cu)

Voltage:

V

Current: µA

100 µg/L 50 µg/L 40 µg/L 30 µg/L 20 µg/L 10 µg/L

-0.3760 5 -3 1 2 6 4

-0.3613 4 2 2 5 -3 4

-0.3369 4 1 5 3 5 4

-0.3174 2 2 5 3 4 3

-0.3076 3 3 7 2 5 5

-0.2783 4 4 6 2 4 3

-0.2686 2 6 2 3 5 1

-0.2393 2 6 5 2 4 4

-0.2441 4 4 5 7 7 4

-0.2246 3 5 7 2 3 5

-0.2051 3 2 3 7 4 3

-0.1855 6 3 5 7 6 2

-0.1709 6 4 7 3 -2 4

-0.1416 3 5 4 6 5 5

-0.1318 5 6 3 7 2 4

-0.1172 2 6 3 5 4 4

-0.1123 5 7 6 5 4 3

-0.1025 5 5 6 5 6 4

-0.0781 5 7 4 4 3 5

-0.0684 3 3 5 4 0 2

-0.0635 5 6 5 4 1 6

-0.0537 4 5 6 2 2 4

0 5 6 6 4 5 2

-0.0293 5 5 2 6 5 7

74

Table A-2 Analysis of the Concentration

Concentration

(µg/L)

Current: µA

Cu (II) Cd (II) Pb (II)

10 -88 ± 4.49 -59± 4.12 -43± 3.48

20 -109± 3.44 -87± 4.09 -58± 3.87

30 -153± 4.42 -94± 3.49 -69± 4.65

50 -181± 4.36 -110± 3.43 -74± 3.89

Table A-3 Analysis 20 µg L-1

of Lead (Pb) 5 Cyclic voltammogrames

Voltage:V

Cyclic 1 Cyclic 2 Cyclic 3 Cyclic 4 Cyclic 5

Current:

µA

Current:

µA

Current:

µA

Current:

µA

Current:

µA

0 0 1 2 0 0

0 -1 1 0 2 1

0 1 2 3 1 3

0.0098 1 1 1 0 1

0.0146 0 1 1 1 1

0.0146 0 1 1 2 1

0.0293 0 2 1 1 1

0.0342 0 1 0 1 0

0.0439 1 2 2 2 1

0.0635 1 3 1 1 1

0.0684 0 0 2 2 1

0.0781 1 2 2 2 1

0.0928 1 2 2 2 2

0.1172 1 1 1 2 2

0.1318 0 2 2 1 2

0.1367 2 3 1 2 2

0.1465 1 2 2 2 3

75

Table A-3 (Continued)

Voltage:V

Cyclic 1 Cyclic 2 Cyclic 3 Cyclic 4 Cyclic 5

Current:

µA

Current:

µA

Current:

µA

Current:

µA

Current:

µA

0.1660 1 3 3 2 3

0.1855 2 3 2 4 3

0.1953 1 2 2 2 3

0.2002 2 3 4 3 2

0.2295 3 2 4 3 2

0.2441 2 2 3 3 3

0.2832 2 4 4 3 3

0.2734 2 3 3 4 3

0.2881 2 3 4 4 4

0.3027 2 3 4 4 3

0.3320 3 3 3 5 4

0.3516 4 4 4 4 3

0.3662 3 3 4 3 4

0.3760 2 3 3 5 4

0.3955 3 4 5 4 5

0.4199 4 4 4 4 4

0.4541 4 4 4 5 4

0.4639 3 5 5 4 5

0.4883 4 4 5 6 5

0.4932 3 5 5 6 5

0.5127 3 6 6 6 5

0.5371 4 6 7 7 5

0.5664 5 6 5 7 5

0.5908 5 7 6 7 6

0.6152 6 8 5 7 5

0.6396 6 6 7 7 8

76

Table A-3 (Continued)

Voltage:V

Cyclic 1 Cyclic 2 Cyclic 3 Cyclic 4 Cyclic 5

Current:

µA

Current:

µA

Current:

µA

Current:

µA

Current:

µA

0.6543 5 7 7 7 6

0.6592 6 7 6 8 7

0.6885 7 8 6 7 6

0.7373 8 7 8 7 7

0.7764 7 7 7 7 8

0.7715 9 7 7 7 8

0.8008 8 8 8 8 6

0.8203 10 9 7 8 8

0.8301 9 8 8 9 9

0.8740 9 9 9 11 9

0.9033 10 8 10 10 9

0.9033 8 9 9 11 9

0.9375 10 8 10 11 10

0.9961 9 8 11 12 10

1.0352 10 9 10 13 10

1.0400 11 11 10 12 11

1.0400 10 11 12 12 11

1.0889 11 9 11 12 11

1.1475 10 11 12 12 12

1.1572 10 13 11 12 11

1.1914 10 12 11 14 10

1.2109 10 12 11 12 11

1.2598 10 13 11 12 11

1.2793 10 11 10 12 10

1.2549 8 13 11 13 9

1.2256 9 10 11 11 10

77

Table A-3 (Continued)

Voltage:V

Cyclic 1 Cyclic 2 Cyclic 3 Cyclic 4 Cyclic 5

Current:

µA

Current:

µA

Current:

µA

Current:

µA

Current:

µA

1.1914 7 8 8 9 8

1.1523 5 8 9 9 10

1.1133 6 7 7 9 7

1.0840 6 7 7 8 6

1.0693 6 6 8 7 7

1.0352 3 6 6 6 5

1.0400 4 6 7 7 6

0.9814 5 5 5 5 5

0.9717 3 5 5 5 6

0.9277 5 4 5 6 6

0.8984 4 5 5 5 5

0.8740 3 4 2 4 5

0.8496 2 5 5 4 5

0.8203 3 5 4 4 5

0.7471 3 3 3 4 4

0.7520 2 4 4 4 4

0.7422 2 3 4 3 4

0.7275 3 4 4 4 3

0.7080 2 2 3 3 2

0.6787 3 2 2 3 3

0.6641 2 3 3 4 2

0.6299 1 2 3 1 2

0.6006 2 3 2 3 2

0.5811 2 3 2 2 2

0.5615 2 2 2 1 2

0.5469 2 2 1 1 2

78

Table A-3 (Continued)

Voltage:V

Cyclic 1 Cyclic 2 Cyclic 3 Cyclic 4 Cyclic 5

Current:

µA

Current:

µA

Current:

µA

Current:

µA

Current:

µA

0.5322 0 1 1 3 1

0.5029 1 1 0 2 1

0.4883 0 1 1 1 1

0.4492 0 0 1 0 1

0.4443 0 -1 -1 -1 1

0.4199 1 1 0 0 0

0.3955 1 0 0 -1 0

0.3809 0 -2 -2 -2 -1

0.3711 1 -1 -2 -1 0

0.3516 0 -1 -2 -1 -1

0.3223 0 -1 0 -1 -2

0.3027 0 -1 -1 -1 -1

0.3027 0 -1 -2 -2 0

0.2930 0 -2 -1 -1 -2

0.2686 1 -2 -2 -1 -1

0.2490 0 0 -2 0 -2

0.2344 0 -3 -2 0 -2

0.1660 -1 -1 -1 -1 -1

0.2002 0 -1 -2 -1 1

0.1807 0 -1 -1 -1 -2

0.1660 -1 -1 -1 -1 -1

0.1514 0 -1 -2 -2 -1

0.1514 0 -2 0 -2 -2

0.1221 -1 -2 -1 -1 -1

0.1074 -1 0 -1 -2 -1

0.1025 0 -1 -1 -2 -1

79

Table A-3 (Continued)

Voltage:V

Cyclic 1 Cyclic 2 Cyclic 3 Cyclic 4 Cyclic 5

Current:

µA

Current:

µA

Current:

µA

Current:

µA

Current:

µA

0.0928 -1 -1 -1 -2 -1

0.0732 -1 -1 -2 -1 -1

0.0635 -1 -1 -1 -1 0

0 -1 0 0 -1 -2

0.0342 -2 0 -1 -1 -2

0.0781 -1 -2 0 -1 0

0.0195 -2 -1 0 -2 -1

0.0098 -1 -2 0 -1 -1

0 0 -2 -1 -2 0

0 -2 -2 -1 -1 -1

0 -5 -1 -1 -1 -1

0 -3 -1 -1 -7 -1

0 -3 -6 -5 -3 -5

-0.005 -3 -2 -3 -3 -3

-0.015 -2 -3 -2 -2 -2

-0.010 -2 -2 -2 -1 -3

-0.034 -3 -2 -2 -3 -3

-0.029 -2 -1 -3 -2 -2

-0.054 -3 -3 -3 -1 -3

-0.064 -3 -3 -3 -3 -3

-0.078 -5 -3 -3 -5 -3

-0.083 -4 -4 -3 -4 -4

-0.098 -4 -4 -4 -4 -3

-0.117 -4 -5 -5 -5 -5

-0.122 -5 -5 -6 -5 -6

-0.151 -6 -6 -6 -7 -6

80

Table A-3 (Continued)

Voltage:V

Cyclic 1 Cyclic 2 Cyclic 3 Cyclic 4 Cyclic 5

Current:

µA

Current:

µA

Current:

µA

Current:

µA

Current:

µA

-0.147 -5 -6 -7 -6 -6

-0.171 -6 -6 -8 -8 -6

-0.186 -7 -8 -9 -9 -7

-0.190 -8 -8 -9 -10 -9

-0.230 -8 -7 -10 -9 -10

-0.220 -9 -10 -9 -11 -9

-0.244 -10 -10 -10 -11 -10

-0.273 -10 -11 -11 -11 -11

-0.278 -12 -11 -11 -11 -12

-0.288 -12 -12 -13 -13 -12

-0.313 -14 -13 -12 -13 -13

-0.332 -13 -13 -13 -14 -13

-0.347 -13 -13 -14 -14 -15

-0.366 -13 -14 -15 -15 -14

-0.371 -15 -17 -15 -16 -15

-0.400 -16 -16 -15 -16 -15

-0.435 -16 -14 -15 -16 -15

-0.444 -15 -17 -15 -14 -17

-0.454 -16 -15 -16 -16 -17

-0.440 -18 -17 -16 -19 -17

-0.508 -18 -19 -17 -20 -18

-0.518 -20 -18 -17 -22 -19

-0.552 -21 -20 -21 -25 -20

-0.571 -24 -22 -23 -26 -23

-0.620 -26 -25 -28 -28 -25

81

Table A-3 (Continued)

Voltage:V

Cyclic 1 Cyclic 2 Cyclic 3 Cyclic 4 Cyclic 5

Current:

µA

Current:

µA

Current:

µA

Current:

µA

Current:

µA

-0.615 -29 -29 -30 -31 -29

-0.625 -33 -31 -34 -35 -30

-0.649 -34 -33 -33 -37 -32

-0.669 -36 -34 -35 -39 -33

-0.703 -38 -37 -37 -39 -37

-0.728 -39 -39 -37 -39 -39

-0.776 -41 -41 -39 -40 -40

-0.772 -42 -41 -41 -41 -39

-0.796 -42 -40 -42 -42 -41

-0.815 -42 -40 -39 -42 -41

-0.835 -42 -40 -40 -41 -41

-0.850 -45 -41 -40 -40 -42

-0.908 -48 -40 -41 -44 -43

-0.933 -54 -42 -44 -46 -44

-0.977 -57 -47 -49 -52 -49

-0.991 -66 -53 -51 -56 -51

-1.006 -75 -56 -57 -65 -58

-1.021 -87 -64 -65 -75 -64

-1.060 -97 -75 -75 -85 -73

-1.099 -107 -85 -85 -94 -83

-1.123 -118 -95 -97 -106 -95

-1.157 -129 -105 -102 -115 -103

-1.182 -135 -117 -113 -123 -116

-1.216 -145 -121 -125 -134 -124

-1.260 -155 -134 -135 -139 -132

82

Table A-3 (Continued)

Voltage:V

Cyclic 1 Cyclic 2 Cyclic 3 Cyclic 4 Cyclic 5

Current:

µA

Current:

µA

Current:

µA

Current:

µA

Current:

µA

-1.299 -164 -142 -146 -150 -144

-1.255 -147 -154 -153 -159 -147

-1.216 -131 -164 -162 -142 -158

-1.162 -117 -145 -141 -125 -140

-1.128 -103 -129 -127 -113 -122

-1.113 -90 -115 -112 -98 -110

-1.079 -79 -101 -99 -86 -96

-1.074 -66 -89 -87 -77 -85

-1.040 -58 -77 -78 -67 -76

-1.006 -51 -68 -66 -57 -67

-0.996 -43 -57 -55 -48 -57

-0.957 -36 -47 -47 -40 -47

-0.913 -29 -41 -41 -34 -40

-0.889 -21 -34 -34 -28 -34

-0.864 -18 -29 -29 -23 -29

-0.845 -14 -22 -22 -17 -23

-0.811 -11 -18 -17 -13 -19

-0.796 -7 -13 -13 -9 -14

-0.776 -6 -8 -9 -6 -10

-0.747 -4 -6 -7 -5 -7

-0.732 -6 -4 -4 -3 -6

-0.689 -7 -2 -2 -2 -6

-0.742 -7 -1 -3 -2 -6

-0.640 -9 -2 -3 -4 -6

-0.635 -9 -3 -4 -7 -6

-0.606 -9 -3 -6 -8 -10

83

Table A-3 (Continued)

Voltage:V

Cyclic 1 Cyclic 2 Cyclic 3 Cyclic 4 Cyclic 5

Current:

µA

Current:

µA

Current:

µA

Current:

µA

Current:

µA

-0.591 -10 -5 -7 -8 -11

-0.571 -10 -7 -9 -9 -10

-0.542 -10 -7 -9 -10 -11

-0.518 -9 -9 -9 -9 -11

-0.508 -8 -8 -11 -11 -11

-0.493 -8 -9 -10 -10 -11

-0.469 -7 -8 -9 -8 -11

-0.435 -7 -7 -9 -8 -10

-0.444 -6 -5 -8 -6 -9

-0.396 -5 -6 -7 -5 -7

-0.386 -4 -4 -5 -4 -6

-0.366 -5 -3 -5 -4 -7

-0.347 -5 -4 -3 -4 -5

-0.327 -4 -4 -4 -4 -5

-0.317 -2 -3 -4 -3 -4

-0.293 -3 -2 -3 -3 -5

-0.337 -3 -4 -3 -3 -5

-0.254 -2 -3 -4 -4 -4

-0.244 -2 -3 -3 -3 -5

-0.234 -2 -1 -3 -2 -3

-0.205 -2 -3 -2 -2 -3

-0.205 -3 -2 -2 -2 -3

-0.181 -2 -2 -2 -3 -4

-0.156 -2 -1 -2 -2 -3

-0.205 -2 -1 -1 -2 -3

-0.137 0 -1 -1 0 -1

84

Table A-3 (Continued)

Voltage:V

Cyclic 1 Cyclic 2 Cyclic 3 Cyclic 4 Cyclic 5

Current:

µA

Current:

µA

Current:

µA

Current:

µA

Current:

µA

-0.171 0 0 -1 0 -2

-0.103 0 -1 -1 0 -2

-0.093 0 0 0 0 -1

-0.088 1 0 0 0 -1

-0.068 1 0 0 -1 0

-0.064 0 1 0 0 -1

-0.049 0 0 1 0 0

-0.039 0 1 0 0 0

-0.024 1 0 1 1 2

-0.064 1 0 1 1 0

-0.015 1 2 0 1 0

85

APPENDIX B

CIRCUIT

86

Figure B-1 Portable voltammetric device for detecting heavy metal contamination

circuit

(a)

Figure B-2 Variable digital voltage

87

(b)

Figure B-3 Negative voltage and OP-Amp inverting

(c)

Figure B-4 Switching pole circuit

88

(d)

Figure B-5 Current sensor circuit and ADC 16Bit I2C (MCP3425)

(e)

Figure B-6 Microcontroller Arduino uno r3

89

(f)

Figure B-7 Display LCD 16X4 Module

(g)

Figure B-9 Micro SD card Module

90

BIOGRAPHY

Name Mrs. Phakhamon Thipnet

Date of birth February 23, 1970

Pace of birth Khon Kaen, Thailand

Present address 22/18, Mabmayom Road, Bangsaen,

MuanChon buri, Chon buri, 20130,

Thailand

Education

1990-1994 Bachelor of Science (B.Sc.),

Faculty of Education,

Prince of Songkla University

Thailand

1995-1999 Master of Science (M.Sc.),

Faculty of Zoology,

Kasetsart University, Thailand

2010 2016 Doctor of Philosophy (Ph.D.),

Faculty of Science, Burapha University,

Chonburi, Thailand