vii
TABLE OF CONTENTS
CHAPTER
TITLE
TITLE
i
DECLARATION
ii
DEDICATION
iii
ABSTRACT
iv
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
xii
LIST OF FIGURES
Xiv
ABBREVATIONS
Xx
LIST OF APPENDICES
1
2
PAGE
Xxiv
INTRODUCTION
1
1.1
Background of the Research
1
1.2
Problem Statement
3
1.3
Objectives of the Research
4
1.4
Scope of the Research
4
LITERATURE REVIEW
6
2.1
Herbicide
6
2.2
Glyphosate and its Metabolite
7
2.2.1
Health Impacts of Glyphosate and
AMPA
12
2.2.2
Environmental Fate of Glyphosate and
AMPA
13
2.3
Analytical Methods for Determination of
Glyphosate and AMPA
14
2.4
Electrochemical Properties of Glyphosate and
AMPA
22
viii
2.5
Voltammetry Method
24
2.5.1
General Overview of Voltammetry
Method
24
2.5.2
Voltammetric Measurement
27
2.5.1
27
2.5.3
3
Instrumentation
Types of Volatmmetry Techniques
28
2.5.3.1
Cyclic Voltammetry (CV)
28
2.5.3.2
Differential Pulse
Voltammetry (DPV)
31
2.5.3.3
Stripping Voltammetry (SV)
33
EXPERIMENTAL
35
3.1
Chemicals and Reagents
35
3.2
General Instruments
35
3.3
Preparation of Stock Solution
38
3.3.1
Glyphosate Solution (1000 ppm)
38
3.3.2
Aminomethylphosphonic Acid
Solution (1000 ppm)
38
3.3.3
Phosphate Buffer, 0.1 M
38
3.3.4
Britton Robinson Buffer (BRB), 0.04 M
38
3.3.5
Sodium Hydroxide (NaOH), 0.1 M
39
3.3.6
Hydrochloric Acid (HCl), 0.1 M
39
3.3.7
Standard Copper (II) Solution (100 ppm)
39
3.3.8
Standard Zinc (II) Solution (100 ppm)
39
3.3.9
Standard Iron (II) Solution (100 ppm)
40
3.3.10 Real Samples
40
3.4
Fabrication of Copper Electrode
40
3.5
Analytical Technique for Voltammetry Analysis
41
3.5.1
General Procedures for Voltammetry
Analysis
41
3.5.2
Cyclic Voltammetry Technique
41
3.5.2.1
Standard Addition Procedure in
CV Study
41
3.5.2.2
Effect of Scan Rate (v) in
CV Study
42
ix
3.5.3
Differential Pulse Voltammetry (DPV)
Technique (Anodic and Cathodic
Direction)
43
3.5.4
Optimization Study for Differential Pulse
Voltammetry (DPV) Technique
43
3.5.4.1
Effect of Supporting Electrolyte
in DPV Study
43
3.5.4.2
Effect of pH in DPV Study
43
3.5.4.3
Effect of Scan Rate (v) in
DPV Study
44
3.5.4.4
Effect of Initial Potential (Ei) in
DPV Study
44
3.5.4.5
Standard Addition Procedure in
DPV Study
44
3.5.5
Differential Pulse Stripping Voltammetry
(DPSV) Technique
45
3.5.6
Optimization Study for Differential Pulse
Stripping Voltammetry (DPSV)
Technique
45
3.5.6.1
Effect of Accumulation
Potential in DPSV Study
46
3.5.6.2
Effect of Accumulation Time in
DPSV Study
46
3.5.6.3
Standard Addition Procedure in
DPSV Study
46
3.5.7
3.7
4
Interference Studies in DPSV Study
46
3.5.7.1
46
Effect of Zn(II) and
Fe(II)
3.5.8
Validation Method
47
3.5.9
Application to Water Samples
47
Flow Chart
49
RESULTS AND DISCUSSION: DETERMINATION
OF GLYPHOSATE AND
AMINOMETHYLPHOSPHONIC ACID USING
COPPER ELECTRODE
50
4.1
Introduction
50
4.2
Cyclic Voltammetry of Glyphosate (GLYP)
and Aminomethylphosphonic Acid (AMPA)
51
x
4.3
Differential Pulse Voltammetry (DPV) of
Glyphosate (GLYP) and Aminomethylphosphonic
Acid (AMPA)
61
4.3.1
Optimization Studies for Differential
Pulse Voltammetry
62
4.3.1.1
Effect of Supporting Electrolyte
62
4.3.1.2
Effect of pH Supporting
Electrolyte
64
4.3.1.3
Effect of Scan Rate, v
66
4.3.1.4
Effect of Initial Potential, Ei
68
4.3.2
4.4
4.3.2.1
71
Calibration Curve of
Glyphosate and AMPA using
DPV
75
4.4.1
Optimization Studies for Differential
Pulse Stripping Voltammetry
76
4.4.1.1
Effect of Accumulation
Potential, Eacc
76
4.4.1.2
Effect of Accumulation Time,
tacc
77
Analysis of Glyphosate and AMPA
by Differential Pulse Cathodic Stripping
Voltammetry (DPCSV)
78
4.4.2.1
79
4.4.3
5
70
Differential Pulse Stripping Voltammetry (DPSV)
of Glyphosate (GLYP) and
Aminomethylphosphonic Acid (AMPA)
4.4.2
4.5
Analysis of Glyphosate and AMPA by
Differential Pulse Voltammetry (DPV)
Calibration Curve of
Glyphosate and AMPA
Interference Studies
81
Determination of Glyphosate and AMPA in
Mineral, Tap and River Water Using DPCSV
83
RESULTS AND DISCUSSION: DETERMINATION
OF GLYPHOSATE AND
AMINOMETHYLPHOSPHONIC ACID USING
HANGING MERCURY DROP ELECTRODE
87
5.1
87
Cyclic Voltammetry of Glyphosate (GLYP) and
Aminomethylphosphonic Acid (AMPA)
xi
5.2
Differential Pulse Voltammetry (DPV) of
Glyphosate (GLYP) and Aminomethylphosphonic
Acid (AMPA)
95
5.2.1
Optimization Studies for Differential
Pulse Voltammetry
5.2.1.1 Effect of Supporting Electrolyte
96
5.2.1.2
Effect of pH of Supporting
Electrolyte
97
5.2.1.3
Effect of Scan Rate, v
98
5.2.1.4
Effect of Initial Potential, Ip
98
5.2.2
5.3
6
96
Analysis of Glyphosate and AMPA by
Differential Pulse Voltammetry (DPV)
100
5.2.2.1
101
Calibration Curve of
Glyphosate and AMPA using
DPV
Differential Pulse Stripping Voltammetry (DPSV)
Studies of Glyphosate (GLYP) and
Aminomethylphosphonic Acid (AMPA)
103
5.3.1
Optimization Studies for Differential
Pulse Stripping Voltammetry
103
5.3.1.1
Effect of Accumulation
Potential, Eacc
103
5.3.1.2
Effect of Accumulation Time,
tacc
104
5.3.2
Calibration Curve of Glyphosate and
AMPA using DPCSV
105
5.3.3
Interference Studies
107
5.4
Determination of Glyphosate and AMPA in
Mineral, Tap and River Water Using DPCSV
109
5.5
Validation Method for Glyphosate and AMPA
using Hanging Mercury Drop Electrode
113
CONCLUSION AND RECOMMENDATIONS
116
6.1
Conclusion
116
6.2
Recommendations
119
REFERENCES
120
Appendices A-B
129
xii
LIST OF TABLES
TABLE NO.
TITLE
PAGE
2.1
Physical Properties of Glyphosate and AMPA
9
2.2
Summary of Analytical Methods Used for the
Determination of Glyphosate and AMPA in Various
Samples
17
2.3
Value of Stability Constants for Cu(II) Complexes with
Glyphosate, and AMPA
23
2.4
Excitation Signal Used In Voltammetry (Skoog et al.,
2004)
25
2.5
Working Electrode and limit of detection (LOD) for
Polarographic and Voltammetric Techniques (Barek et
al., 2001)
26
2.6
The Characteristics of Reversible, Irreversible and
Quasi-reversible System (Wang, 1994)
31
3.1
Standard Additions of Glyphosate and AMPA in Cyclic
Voltammetry Technique using Copper Electrode
42
3.2
Standard Additions of Glyphosate and AMPA in Cyclic
Voltammetry Technique using HMDE
42
4.1
The Reduction and Oxidation Potentials of Glyphosate
and AMPA at Copper Electrode in 0.1 M in phosphate
buffer at pH 6.4. Ei = 500 mV, Ef = -600 mV and v = 100
mV/s
55
4.2
The Slope Values for the Log Plot of Peak Current vs
Scan Rate for Glyphosate and AMPA and Peak
Separation of Glyphosate and AMPA at Copper Electrode
in 0.1 M Phosphate Buffer at pH 6.4. Ei = + 500 mV and
Ef = - 600 mV vs SCE, v = 100 mV/s
57
4.3
The Dependence of Peak Current of Glyphosate and
AMPA to Their Concentrations Obtained by Cyclic
Voltammetry inPhosphate Bufferat pH6.4. Ei = + 500 mV
Ef = - 600 mV vs SCE and v = 100 mV/s
60
4.4
The Optimum Parameters of Glyphosate and AMPA
using DPV
70
xiii
4.5
The Value Ip and Ep of Glyphosate and AMPA obtained
by Optimized Parameters in Phosphate Buffer at pH 6.4
using DPV
70
4.6
The Summary of Calibration Results of Glyphosate and
AMPA using DPV
The Optimization Results of Glyphosate and AMPA
using DPV
The Optimum Parameters of Glyphosate and AMPA
using DPCSV
The Summary Results of Glyphosate and AMPA using
DPCSV
75
4.10
Recovery of Glyphosate in Water Samples
83
4.11
Recovery of AMPA in Water Samples
85
4.12
Recovery of Glyphosate in Water Samples
84
4.13
Recovery of AMPA in Water Samples
86
4.14
Comparison of Glyphosate’s Recoveries in Water
Samples
88
4.15
Comparison of AMPA’s Recoveries in Water Samples
88
5.1
The Reduction and Oxidation Potentials of Glyphosate
and AMPA at HMDE in 0.1 M in phosphate buffer at pH
6.4. Ei = + 200 mV and Ef = - 300 mV vs Ag/AgCl and
v = 100 mV/s and Slope Values for the Log Plot of Peak
Current vs Scan Rate for Glyphosate and AMPA
89
5.2
Cyclic Voltammetry Peak Separation of Glyphosate and
AMPA at HMDE in 0.1 M Phosphate Buffer at pH 6.4.
Ei = + 500 mV and Ef = - 600 mV vs SCE, v = 100 mV/s
92
5.3
The Optimum Parameters of Glyphosate and AMPA
using DPV
100
5.4
The Value Ip and Ep of Glyphosate and AMPA obtained
by Optimized Parameters in Phosphate Buffer at pH 6.4
using DPV
100
5.5
The Summary of Calibration Results of Glyphosate and
AMPA using DPV
101
5.6
The Summary Results of Glyphosate and AMPA using
DPCSV
107
5.7
Recovery of Glyphosate in Water Samples
109
5.8
Recovery of AMPA in Water Samples
111
5.9
Comparison of Glyphosate’s Recoveries in Water
Samples
Comparison of AMPA’s Recoveries in Water Samples
114
4.7
4.8
4.9
5.10
76
78
81
114
xiv
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
1.1
Degradation Products of Glyphosate
2
2.1
Structure of Glyphosate
8
2.2
Structure of Aminomethylphosphonic Acid (AMPA)
8
2.3
Ionic Species of Glyphosate and their pKa Values
10
2.4
Diagram of Species Distribution with the Function of pH.
a) Glyphosate and b) AMPA (Coutinho et al., 2009)
11
2.5
Glyphosate Degradation Pathway (Schuette, 1998)
12
2.6
An Electrochemical Cell Consists of Three Electrode
System
27
2.7
Potential Waveform in Cyclic Voltammetry(Wang, 1994)
28
2.8
A Cyclic Voltammogram (O = Oxidation, R = Reduction)
(Wang, 1994)
28
2.9
Cyclic Voltammograms of (a) Reversible, (b) Irreversible
and (c) Quasi-reversible Reactions (ox = Oxidation
Process and red = Reduction Process) (Fernandez, 2009)
30
2.10
Potential Wave Form for Differential Pulse Voltammetry
(Wang, 1994)
32
2.11
A Differential Pulse Voltammogram (Wang, 1994)
33
2.12
Potential Wave Form of Anodic Stripping Voltammetry
(Wang, 1994)
34
2.13
A Stripping Voltammogram (Zhi et al, 2010)
34
3.1
Eco-Tribo Polarography Analyzer Equipped with Polar
Pro Version 1.0 Software
36
3.2
AD Instruments Power Lab (EDAQ) Analyzer Equipped
with Echem Version 1.5 Software
37
3.3
Eco-Chemie B.V Autolab Analyzer Equipped with GPES
Version 4.9.005 Software
37
3.4
Copper Working Electrode (A= copper wire, B= wire and
C= connector)
40
xv
3.5
Flow chart of the study process
49
4.1
Influence of the Phosphate Buffer at Different pH on the
Microelectrode Dissolution in the presence of
0.5 × 10-3 M Glyphosate (Coutinho et al., 2007a)
52
4.2
Cyclic Voltammogram of Glyphosate in Phosphate
Buffer at pH 6.4. Glyphosate Concentration: a) 0,
b) 2.96 × 10-6 M. Ei = + 500 mV and Ef = - 600 mV vs
SCE and v = 100 mV/s
53
4.3
Cyclic Voltammogram of AMPA in Phosphate Buffer at
pH 6.4. AMPA Concentration: a) 0, b) 9.01 × 10-6 M.
Ei = + 500 mV and Ef = - 600 mV vs SCE and
v = 100 mV/s
53
4.4
Proposed Structure of Cu(II) complex with Glyphosate
and AMPA at pH 6.4
54
4.5
Cyclic Voltammograms at Copper Microelectrode in
Phosphate Buffer. Solid Line: 0.25 mM Glyphosate;
Dashed Line: 0 mM Glyphosate. v = 100 mV/s and
Ei = -600 mV, (Coutinho et al., 2007c)
55
4.6
Cyclic Voltammogram of Glyphosate in Phosphate
Buffer at pH 6.4 at Different Scan Rate. Glyphosate
Concentration: 2.96 × 10-6 M. Ei = + 500 mV and
Ef = - 600 mV vs SCE
56
4.7
Log plot of Peak Current vs Scan Rate for a) Oxidation
Peak and b) Reduction Peak of Glyphosate.
Ei = + 500 mV and Ef = - 600 mV vs SCE
57
4.8
Cyclic Voltammogram of Glyphosate in Phosphate
Buffer at pH 6.4. Glyphosate Concentration: a) 0,
b) 2.96 × 10-6 M, c) 5.92 × 10-6 M, d) 8.88 × 10-6 M,
e) 1.18 × 10-5 M. Ei = + 500 mV Ef = - 600 mV vs SCE
and v = 100 mV/s
58
4.9
Cyclic Voltammogram of AMPA in Phosphate Buffer at
pH 6.4. AMPA Concentration: a) 0, b) 9.01 × 10-6 M,
c)1.80 × 10-5 M, d) 2.70 × 10-5 M,
e) 3.60 × 10-5 M.
Ei = + 500 mV Ef = - 600 mV vs SCE and v = 100 mV/s
59
4.10
Peak Current of a) Oxidation Peak and b) Reduction Peak
of Glyphosate with increasing concentration of
Glyphosate. Ei = + 500 mV Ef = - 600 mV vs SCE and
v = 100 mV/s
Voltammogram of Glyphosate, 1.18 × 10-6 M in
Phosphate Buffer at Variation of pH. Ei = 100 mV,
Ef = - 300 mV, v = 100 mV/s, Cathodic Direction
59
Ip versus Type of Supporting Electrolyte at pH 6.4 of
a) Glyphosate, 1.18 × 10-6 M and b) AMPA,
7.20 × 10-6 M. Ei = - 600 mV, Ef = 600 mV, v = 100
mV/s, Anodic Direction
63
4.11
4.12
61
xvi
4.13
Ip versus Type of Supporting Electrolyte at pH 6.4 of a)
Glyphosate, 1.18 × 10-6 M and b) AMPA, 7.20 × 10-6 M.
Ei = 100 mV, Ef = -300 mV, v = 100 mV/s, Cathodic
Direction
63
4.14
Ip and Ep versus pH of a) Glyphosate, 1.18 × 10-6 M and
b) AMPA, 7.20 × 10-6 M in 0.1 M Phosphate Buffer.
Ei = -600 mV, Ef = 600 mV, v = 100 mV/s, Anodic
Direction
65
4.15
Ip and Ep versus pH of a) Glyphosate, 1.18 × 10-6 M and
b) AMPA, 7.20 × 10-6 M in 0.1 M Phosphate Buffer.
Ei = 100 mV, Ef = -300 mV, v = 100 mV/s, Cathodic
Direction
65
4.16
Ip and Ep versus scan rate of a) Glyphosate, 1.18 × 10-6 M
and b) AMPA, 7.20 × 10-6 M in 0.1 M Phosphate Buffer
at pH 6.4, Ei = -600 mV and Ef = 600 mV, Anodic
Direction
67
4.17
Ip and Ep versus scan rate of a) Glyphosate, 1.18 × 10-6 M
and b) AMPA, 7.20 × 10-6 M in 0.1 M Phosphate Buffer
at pH 6.4, Ei = 100 mV, Ef = - 300 mV, Cathodic
Direction
67
4.18
Ip and Ep versus Initial Potential of a) Glyphosate,
1.18 × 10-6 M and b) AMPA, 7.20 × 10-6 M in 0.1 M
Phosphate Buffer at pH 6.4, Ef = 600 mV and
v = 80 mV/s, Anodic Direction
69
4.19
Ip and Ep versus Initial Potential of a) Glyphosate,
1.18 × 10-6 M and b) AMPA, 7.20 × 10-6 M in 0.1 M
Phosphate Buffer at pH 6.4.Ef = - 300 Mv and v = 100
mV/s, Cathodic Direction
69
4.20
DP Voltammogram by Anodic Direction of a) Glyphosate
and b) AMPA in Phosphate Buffer at pH 6.4.
Ei = -600/ -700 mV, Ef = 600 mV and v = 80 mV/s
72
4.21
DP Voltammogram by Cathodic Direction of a)
Glyphosate and b) AMPA in Phosphate Buffer at pH 6.4.
Ei = 600/ 800 mV, Ef = - 350 mV and v = 100 mV/s
73
4.22
Linear Plot of a) Glyphosate and b) AMPA in Phosphate
Buffer at pH 6.4 using DPV, Anodic Direction
74
4.23
Linear Plot of a) Glyphosate and b) AMPA in Phosphate
Buffer at pH 6.4 using DPV, Cathodic Direction
74
4.24
Ip versus Accumulation Potential of a) Glyphosate,
1.18 × 10-6 M and b) AMPA, 7.20 × 10-6 M in 0.1 M
Phosphate Buffer at pH 6.4. Ei = 600/800 mV,
Ef = - 500 mV and v = 100 mV/s
77
xvii
4.25
Ip versus Accumulation Time of a) Glyphosate,
1.18 × 10-6 M and b) AMPA, 7.20 × 10-6 M in 0.1 M
Phosphate Buffer at pH 6.4. Ei = 600/800 mV,
Ef = -500 mV, v = 80 mV/s and Eacc = -500/-600 mV
78
4.26
DPCS Voltammogram of a) Glyphosate and b) AMPA in
Phosphate Buffer at pH 6.4. Ei = 600/ 800 mV,
Ef = -500 mV v = 100 mV/s, Eacc = 500 mV and
tacc = 10/20 s
80
4.27
Linear Plot of a) Glyphosate b) AMPA in Phosphate
Buffer at pH 6.4 using DPCSV
81
4.28
The Graph of Ipof a) Glyphosate and b) AMPA with
Increasing Concentration of Fe2+ and Zn2+ ion in
Phosphate Buffer at pH 6.4 using DPCSV
82
4.29
DPCS Voltammogram with Added 0.5 ppm Glyphosate
in a) Mineral Water, b) Tap Water and c) River Water in
Phosphate Buffer at pH 6.4
84
4.30
DPCS Voltammogram with Added 2 ppm AMPA in a)
Mineral Water, b) Tap Water and c) River Water in
Phosphate Buffer at pH 6.4
86
5.1
Cyclic Voltammogram of Glyphosate in 0.1 M Phosphate
Buffer at pH 6.4. Glyphosate Concentration: a) 0,
b) 5.92 × 10-7 M. Ei = + 200 mV and Ef = - 300 mV vs
Ag/AgCl and v = 100 mV/s. Cu2+ = 7.11 × 10-5 M
88
5.2
Cyclic Voltammogram of AMPA in 0.1 M Phosphate
Buffer at pH 6.4. AMPA Concentration: a) 0,
b) 2.25× 10-6 M. Ei = + 200 mV and Ef = - 300 mV vs
Ag/AgCl and v = 100 mV/s. Cu2+ = 7.11 × 10-5 M
88
5.3
Cyclic Voltammogram of Glyphosate in Phosphate
Buffer at pH 6.4 at Different Scan Rate. Glyphosate
Concentration: 5.92 × 10-7 M. Ei = + 200 mV and
Ef = - 300 mV vs Ag/AgCl
90
5.4
Cyclic Voltammogram of AMPA in Phosphate Buffer at
pH 6.4 at Different Scan Rate. AMPA Concentration:
2.25 × 10-6 M. Ei = + 200 mV and Ef = - 300 mV vs
Ag/AgCl
90
5.5.
Log plot of Peak Current vs Scan Rate for a) Oxidation
Peak and b) Reduction Peak of Glyphosate.
Ei = + 200 mV and Ef = - 300 mV vs Ag/AgCl
91
5.6
Log plot of Peak Current vs Scan Rate for a) Oxidation
Peak and b) Reduction Peak of AMPA. Ei = + 200 mV
and Ef = - 300 mV vs Ag/AgCl
91
xviii
5.7
Cyclic Voltammogram of Glyphosate in Phosphate
Buffer at pH 6.4. Glyphosate Concentration: a) 0,
b) 5.92 × 10-7 M, c)1.18 × 10-6 M, d) 1.78 × 10-6 M,
e) 2.37 × 10-6 M. Ei = + 200 mV and Ef = - 300 mV vs
Ag/AgCl and v = 100 mV/s. Cu2+ = 7.11 × 10-5 M
93
5.8
Cyclic Voltammogram of AMPA in Phosphate Buffer at
pH 6.4. AMPA Concentration: a) 0, b) 2.25 × 10-6 M,
c) 4.50 × 10-5 M, d) 6.75 × 10-5 M, e) 9.01 × 10-6 M.
Ei = + 200 mV and Ef = - 300 mV vs Ag/AgCl and
v = 100 mV/s. Cu2+ = 7.11 × 10-5 M
93
5.9
Peak Current of Reduction Peak of a) Glyphosate and b)
AMPA with Increasing Concentration. Ei = + 200 mV
and Ef = - 300 mV vs Ag/AgCl and v = 100 mV/s
94
5.10
Voltammogram of Glyphosate, 2.96 × 10-7 M in
Phosphate Buffer at Variation of pH. Ei = + 200 mV,
Ef = - 300 mV, v = 100 mV/s
95
5.11
Ip versus Type of Supporting Electrolyte at pH 6.4 of a)
Glyphosate, 2.96 × 10-7 M and b) AMPA, 1.35 × 10-6 M.
Ei = + 200 mV, Ef = -300 mV, v = 100 mV/s
96
5.12
Ip and Ep versus pH of 0.1 M Phosphate Buffer of a)
Glyphosate, 2.96 × 10-7 M and b) AMPA, 1.35 × 10-6 M.
Ei = + 200 mV, Ef = -300 mV, v = 100 mV/s
97
5.13
Ip and Ep versus scan rate of a) Glyphosate, 2.96 × 10-7 M
and b) AMPA, 1.35 × 10-6 M. Ei = + 200 mV,
Ef = -300 mV
98
5.14
Ip and Ep versus Initial Potential of a) Glyphosate,
2.96 × 10-7 M and b) AMPA, 1.35 × 10-6 M.
Ef = - 300 mV, v = 100 mV/s
99
5.15
Linear Plot of a) Glyphosate and b) AMPA in Phosphate
Buffer at pH 6.4 using DPV
101
5.16
DP Voltammogram of a) Glyphosate and b) AMPA in
Phosphate Buffer at pH 6.4. Ei = + 210/200 mV,
Ef = -300 mV, v = 100 mV/s
102
5.17
Ip versus Accumulation Potential of a) Glyphosate,
2.96 × 10-7 M and b) AMPA, 1.35 × 10-6 M in 0.1 M
Phosphate Buffer at pH 6.4. Ei = + 210/200 mV,
Ef = -350 mV and v = 100 mV/s
104
5.18
Ip versus Accumulation Time of a) Glyphosate,
2.96 × 10-7 M and b) AMPA, 1.35 × 10-6 M in 0.1 M
Phosphate Buffer at pH 6.4. Ei = + 210/200 mV,
Ef = -350 mV and v = 100 mV/s and Eacc = 200 mV
105
xix
5.19
DPCS Voltammogram of a) Glyphosate and b) AMPA in
Phosphate Buffer at pH 6.4. Ei = + 210/200 mV,
Ef = - 350 mV v = 100 mV/s, Eacc = 200 mV and
tacc = 20/30 s
106
5.20
Linear Plot of a) Glyphosate b) AMPA in Phosphate
Buffer at pH 6.4 using DPCS
107
5.21
The Graph of Ip of a) Glyphosate and b) AMPA with
Increasing Concentration of Fe2+ and Zn2+ ion in
Phosphate Buffer at pH 6.4 using DPCSV
108
5.22
DPCS Voltammogram with Added 0.17 ppm Glyphosate
in a) Mineral Water, b) Tap Water and c) River Water in
Phosphate Buffer at pH 6.4
110
5.23
DPCS Voltammogram with Added 0.5 ppm AMPA in a)
Mineral Water, b) Tap Water and c) River Water in
Phosphate Buffer at pH 6.4
112
5.24
Linear Plot of a) Glyphosate b) AMPA in Phosphate
Buffer at pH 6.4 using DPCSV by HMDE
114
5.25
DPCS Voltammogram of a) Glyphosate and b) AMPA in
Phosphate Buffer at pH 6.4 using HMDE.
Ei = + 210/ 200 mV, Ef = - 300 mV, v = 100 mV/s,
Eacc = 200 mV and tacc = 20/30 s
115
A-1
Cyclic Voltammogram of AMPA in Phosphate Buffer at
pH 6.4at Different Scan Rate. AMPA Concentration:
9.01 × 10-6 M. Ei = + 500 mV and Ef = - 600 mV vs SCE
129
A-2
Peak Current of a) Oxidation Peak and b) Reduction Peak
of AMPA with Increasing Scan Rate of AMPA.
Ei = + 500 mV and Ef = - 600 mV vs SCE
129
B-1
Peak Current of a) Oxidation Peak and b) Reduction Peak
of AMPA with Increasing Concentration of AMPA using
CV. Ei = + 500 mV and Ef = - 600 mV vs SCE, v = 100
mV/s
130
xx
ABBREVATIONS
%
-
Percent
µm
-
Micrometer
µgL-1
-
Microgram per Liter
2,4-D
-
2,4-dichlorophenoxyacetic acid
Ag/AgCl
-
Silver/Silver Chloride
Al(NO3)3
-
Aluminium Nitrate
ACP
-
Alternate Current Polarography
ACV
-
Alternate Current Voltammetry
AMPA
-
Aminomethylphosphonic Acid
ASV
-
Anodic Stripping Voltammetry
BRB
-
Britton-Robinson Buffer
CD
-
Coulometric Detector
CE
-
Capillary Electrophoresis
CGS
-
Capillary Gas Chromatography
C3H8NO5P
-
Glyphosate
CH3COOH
-
Glacial Acetic Acid
CH6NO3P
-
Aminomethylphosphonic Acid
CNLSD
-
Condensation Nucleation Light Scattering Detection
CSV
-
Cathodic Stripping Voltammetry
CuE
Copper Electrode
CV
-
Cyclic Voltammetry
DME
-
Dropping Mercury Electrode
DPASV
-
Differential Pulse Anodic Stripping Voltammetry
DPP
-
Differential Pulse Polarography
DPV
-
Differential Pulse Voltammetry
Eacc
-
Accumulation Potential
Ei
-
Initial Potential
Ef
Final Potential
xxi
ECD
-
Electron Capture Detector
EI-MS
-
Electron Impact Mass Spectrometry
ES-MS
-
Electrospray Mass Spectrometry
ESI-MS
-
Electrospray Ionization Mass Spectrometry
ELISA
-
Enzyme-Linked Immunosorbant Assays
EPA
-
Environmental Protection Agency
EPSPS
-
5-enolpyruvylshikimate-3-phosphatesynthase
FD
-
Fluorescence Detection
FMOC-CI
-
9-fluorenyl-methyloxycarbonyl chloroformate
FPD
-
Flame Photometric Detector
g
-
Gram
GC
-
Gas Chromatography
GLYP
-
Glyphosate
H3BO3
-
Boric Acid
HCl
-
Hydrochloric Acid
H3PO4
-
Orthophosphoric Acid
HILIC
-
Hydrophilic Interaction Chromatography
HMDE
-
Hanging Mercury Dropping Electrode
HPIC-ICP-DRC-MS-
High Performance Ion Chromatography coupled to
Inductively Coupled Plasma Dynamic Reaction Cell
Mass Spectrometry
HPLC
-
High Performance Liquid Chromatography
HPR
-
Horseradish Peroxidase
Ip
-
Peak Current
IC
-
Ion Chromatography
ICP-MS
-
Inductive Coupled Plasma Mass Spectrometry
IMAC
-
Immobilized Metal Ion Affinity
IT-MS
-
Ion Trap Mass Spectrometry
Ka
Acid Dissociation Constant
KCl
-
Potassium Chloride
KH2PO4
-
Potassium Dihydrogen Phosphate
KNO3
-
Potassium Nitrate
LC
-
Liquid Chromatography
L’ELISA
-
Linker Enzyme Linked Immunosorbant Assay
xxii
LOD
-
Limit of Detection
LOQ
-
Limit of Quantification
LQ
-
Liquid Chromatography
M
-
Molar
mL
-
Milliliter
Mv/s
-
Milivolt per Second
MS
-
Mass Chromatography
N2
-
Nitrogen Gas
NaCl
-
Sodium Chloride
Na2HPO4
-
Disodium Hydrogen Phosphate
NaOH
-
Sodium Hydroxide
NPD
-
Nitrogen Phosphorus Detector
NPP
-
Normal Pulse Polarography
NPV
-
Normal Pulse Voltammetry
ng ml-1
-
Nanogram per Mililiter
Ni(NO3)2
Nickel Nitrate
NiAl-NO3-LDH
Nickel Aluminium Nitrate Layered Double Hydroxide
OPA-MERC
-
o-phthaldehyde-mercaptoethanol
pKa
- log10Ka
p-value
Probability value
POEA
-
Polyoxyethylene Amine
PBS
-
Phosphate buffer saline
ppm
-
Part per Million
PF-PD
-
Pulsed Flame Photometric Detector
R2
-
Correlation Coefficient
SCE
-
Saturated Calomel Electrode
SCV
-
Stair Case Voltammetry
SME
-
Supported Liquid Membrane
SPE
-
Solid Phase Extraction
SPE
-
Screen Printed Electrode
SWP
-
Square Wave Polarography
SWV
-
Square Wave Voltammetry
SWSV
-
Square Wave Stripping Voltammetry
TFAA
-
Trifluoroacetic Anhydride
xxiii
TFE
-
Trifluoroethanol
tacc
-
Accumulation Time
UME
-
Ultramicroelectrode
US
-
United State
UVD
-
Ultraviolet Detector
υ
-
Scan Rate
xxiv
LIST OF APPENDICES
APPENDIX
TITLE
PAGE
A
Cyclic voltammogram of AMPA on the effect of scan rate
and the dependence of peak current of AMPA on their
scan rate
129
B
Dependence of the peak current of AMPA on their
concentrations using CV
130