viii
TABLE OF CONTENTS
CHAPTER
TITLE
PAGE
THESIS STATUS DECLARATION
SUPERVISOR’S DECLARATION
1
2
TITLE PAGE
i
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRACT
vi
ABSTRAK
vii
TABLE OF CONTENTS
viii
LIST OF TABLES
xiv
LIST OF FIGURES
xix
LIST OF SYMBOLS
xxvii
LIST OF ABBREVIATIONS
xxviii
LIST OF APPENDICIES
xxx
SUMMARY OF THESIS
1
1.1 Background
1
1.2 Summary
2
INTRODUCTION
6
2.1 Pesticides: Usage and Problems
6
2.1.1
Organophosphorus Pesticides (OPPs) in
World Agriculture
7
ix
2.1.2
OPPs in Malaysian Agriculture: A
7
Scenario
2.1.3
Environmental Entry of OPPs
8
2.1.4
Separation and Detection of OPPs by Gas
9
Chromatography and HPLC
2.2 Capillary Electrophoresis (CE)
2.2.1
Electroosmotic Flow (EOF) and its
10
12
Control
2.3 Micellar Electrokinetic Chromatography (MEKC)
2.3.1
Retention Factor (k), Resolution (Rs) and
15
17
Peak Capacity (n)
2.3.2
Selectivity Control in MEKC
18
2.3.2.1
Role of Surfactants
19
2.3.2.2
Role of Buffers
23
2.3.2.3
Effect of Organic Modifiers
26
2.3.2.4
Effect of Cyclodextrin as Buffer
28
Additives
2.3.2.5
Temperature and
28
Thermodynamic Effect
2.3.2.6
2.3.3
Sample Injection Methods in CE
30
Online Sample Concentration
34
2.3.3.1
Stacking
35
2.3.3.2
Sweeping
37
2.3.3.3
Field Enhanced Sample Injection
39
(FESI)
2.3.4 Detection in MEKC
40
2.3.5 Applications of MEKC
41
2.3.6
42
Other Applications of MEKC:
Approaches Using k to Relate and
Estimate the Partition Coefficients
2.3.7 Separation of OPPs by MEKC
2.4 Aims and Objectives
2.4.1
OPPs Selection
43
45
46
x
2.4.2
3
4
Objectives
47
MATERIALS AND METHODS
49
3.1 Chemicals
49
3.2 Instruments
52
3.3 Procedures
53
3.4 Run Methods
54
3.5 Calculations of Parameters
55
OPTIMIZATION OF HYDROPHOBIC OPPs
57
SEPARATION
4.1 Pre-Optimization in Initial MEKC Studies
57
4.2 Extended Optimization
62
4.2.1
Buffer Optimization
64
4.2.1.1
Separation in Borate Buffer
64
4.2.1.2
Separation in Phosphate Buffer
65
4.2.1.3
Separation in Mixed Buffer
70
4.2.1.4
Comparison in Phosphate and
75
Mixed Buffer
4.2.2
Modifier Optimization
80
4.2.2.1
81
Individual Modifiers:
Acetonitrile, 2- Propanol,
Methanol
4.2.2.2
Mixed Modifier
88
4.2.2.3
Comparison of Separation
92
Parameters in 10 % v/v
Methanol and 10 % v/v Mixed
Modifier
4.2.3
Sample Matrix Optimization
97
4.2.4
Comparison of Separation Parameters in
100
Three Sample Matrices
4.2.5
Selection of Sample Injection Mode
102
4.2.6
Selection of Detection Wavelength
106
xi
4.2.7
Conclusions
4.3 Functional
Relationship
108
of
Migration
and
109
Separation Potential: an Alternative Approach to
Predict the k Value
4.3.1
Separation of the Hydrophilic OPPs in the
115
Same MEKC Method – Test of Approach
to Predict k Values
4.4 Correlation Between log k and log Values of
118
Octanol/Water Partition Coefficients (log Kow)
5
QUANTITATIVE ASPECTS OF HYDROPHOBIC
123
OPPs SEPARATION
5.1 Separation of Hydrophobic OPPs in MEKC with
123
Basic Buffer and SDS
5.1.1
Calibration Lines, Linearity (r2), LODs
124
5.1.2
Reproducibility, Efficiency (N),
126
Resolution (Rs)
5.1.3
Online Concentration Methods
130
5.1.3.1
Stacking
131
5.1.3.2
Sweeping
134
5.2 Separation of Hydrophobic OPPs in MEKC with
144
Acidic Buffer and SDS
5.2.1
Calibration Lines, r2, LODs
146
5.2.2
Reproducibility, N, Rs
148
5.2.3
Online Concentration Methods
148
5.2.3.1
Stacking
149
5.2.3.2
Sweeping
150
5.3 Separation of Hydrophobic OPPs in MEKC with
154
Basic Buffer, SDS and Cyclodextrins (CDs)
5.3.1 Separation in β-CD
155
5.3.2 Separation in γ-CD
156
5.3.3 Online Concentration in γ-CD
160
xii
5.4 Separation of Hydrophobic OPPs in MEKC with
162
Basic Buffer and SC
5.4.1
Calibration Lines, r2, LODs
165
5.4.2
Reproducibility, N
166
5.4.3
Online Concentration Methods
169
5.4.3.1
Stacking
169
5.4.3.2
Sweeping
171
5.4.3.3
Field Enhanced Sample Injection
172
(FESI)
6
5.5 Application of Proposed Method
174
5.6 Concluding Remarks
176
HYDROPHILIC OPPS SEPARATION
178
6.1 Separation of Hydrophilic OPPs in MEKC with
178
Basic Buffer
6.1.1
Calibration lines, Linearity (r2), LODs
181
6.1.2
Reproducibility, Efficiency (N),
182
Resolution (Rs)
6.1.3
Stacking in Basic Buffer
185
6.1.3.1
Calibration Lines, r2, LODs
186
6.1.3.2
Reproducibility, N, R
188
6.2 Separation of Hydrophilic OPPs in MEKC with
194
Acidic Buffer
6.2.1
Calibration Lines, r2, LODs
194
6.2.2
Reproducibility, N, Rs
196
6.2.3
Stacking in Acidic Buffer
6.2.4
197
2
6.2.3.1
Calibration Lines, r , LODs
203
6.2.3.2
Reproducibility, N, Rs
205
Application of SRMM
6.3 Concluding Remarks
7
CONCLUSIONS AND SUGGESTIONS FOR
FUTURE STUDY
209
210
211
xiii
7.1 Conclusions
211
7.2 Scope and Limitations
213
7.3 Recommendations for Future Study
214
REFERENCES
Appendices A - F
216
233-257
xiv
LIST OF TABLES
TABLE NO.
2.1
TITLE
Consumption of OPPs (in MT) in Malaysia in year 1990
PAGE
7
to1992
2.2
Recommended OPPs by Department of Agriculture (DOA)
8
under Ministry of Agriculture and Agro-Based Industry
(MOA), Malaysia for certain fruits and vegetables
2.3
Critical micellar concentration (CMC) and their average
20
aggregation number (AN) of surfactants in water at 25º C
2.4
Common buffers in MEKC and their useful pH ranges
24
2.5
Physical data of the common three (α, β, γ) – Cyclodextrin
30
2.6
Effect of capillary ID on sample plug and volume
31
3.1
Selected properties of hydrophobic OPPs
50
3.2
Selected properties of hydrophilic OPPs
50
4.1
Range of buffers, surfactants and modifiers used in the
58
initial optimization studies at pH 9.3
4.2
Regression Equations and the linearity (r2) of migration
69
times of hydrophobic OPPs in the range of phosphate
buffer (on the basis of Figure 4.10)
4.3
Mean peak height (mV) and RSD (n = 3) of hydrophobic
73
OPPs in various concentration of mixed buffer with 5%
MeOH
4.4
Regression equations and linearity (r2) of EOF of
hydrophobic OPPs in the range of phosphate and mixed
buffer {Figure 4.16 (F)}
79
xv
4.5
Descriptors of methanol and acetonitrile used as modifiers
96
in the electrophoretic separation buffer for hydrophobic
OPPs
4.6
Regression Equations and linearity (r2) of EOF of
96
hydrophobic OPPs in the range of methanol and mixed
modifier {on the basis of Figure 4.31 (F)}
4.7
λmax of OPPs of 50 ppm solution in MeOH
107
4.8
Calculated log k values of hydrophobic OPPS at two
113
different mixed modifier percentages
4.9
Equations and r2 for the relationship between applied
115
potentials and migration time of hydrophobic OPPs (on the
basis of Figure 4.42)
4.10
Equations and r2 of the relation between potentials and
117
migration time of hydrophilic OPPs
4.11
Simulated (by an online software) and referred log Kow
119
values of hydrophobic OPPs
4.12
Regression Equations of log k and log Kow (s) and log Kow
120
(m)
4.13
Calculated log Kow for hydrophobic OPPs and hydrophilic
121
OPPs using log Kow (m) regression equation
5.1
Equation of calibration curves, r2, LODs (for S/N = 3) on
126
the basis of peak areas and peak heights of hydrophobic
OPPs separation in NM-MEKC-SDS
5.2
Injected concentration of various pesticides (as run sample
127
or standards) in other MEKC studies
5.3
Reproducibility (RSD) of migration time (min), peak
128
height (mV) and peak areas (mVs) of the separation of
hydrophobic OPPs in NM-MEKC-SDS
5.4
Comparison of peak areas (mVs) and peak heights (mV) of
hydrophobic OPPs separated in NM-MEKC-SDS and
stacking
134
xvi
5.5
Equation of calibration curves, r2, LODs (for S/N = 3) on
138
the basis of peak areas and peak heights of hydrophobic
OPPs separation in sweeping-NM-MEKC-SDS
5.6
RSD of migration time (min), peak height (mV) and peak
139
areas (mVs) of the separation of hydrophobic OPPs in
sweeping-NM-MEKC-SDS
5.7
Sensitivity enhancement in sweeping-NM-MEKC-SDS
139
over NM-MEKC-SDS in separation of hydrophobic OPPs
5.8
Equation of calibration curves, r2, LODs (for S/N = 3) on
141
the basis of peak areas and peak heights of three
hydrophobic OPPs in sweeping-NM-MEKC-SDS
5.9
RSD of migration time (min), peak height (mV) and peak
142
areas (mVs) of the separation of three hydrophobic OPPs
in sweeping-NM-MEKC-SDS
5.10
Sensitivity enhancement in sweeping-NM-MEKC-SDS
142
over NM-MEKC-SDS in separation of three hydrophobic
OPPs
5.11
Sensitivity improvement in MEKC separation of pesticides
143
by online concentration methods in other reported works
5.12
Equation of calibration curves, r2, LODs (for S/N = 3) on
147
the basis of peak areas and peak heights of three
hydrophobic OPPs in RM-MEKC-SDS
5.13
RSD of migration time (min), peak height (mV) and peak
148
areas (mVs) of the separation of three pesticides of
hydrophobic OPPs in RM-MEKC-SDS
5.14
Comparison of peak areas (mVs) and peak heights (mV) of
150
three pesticides of hydrophobic OPPs separated in RMMEKC-SDS and stacking
5.15
Equation of calibration curves, r2, LODs (for S/N = 3) on
the basis of peak areas of three hydrophobic OPPs in
sweeping-RM-MEKC-SDS
152
xvii
5.16
Sensitivity enhancement in sweeping-RM-MEKC-SDS
153
over RM-MEKC-SDS in separation of three pesticides of
hydrophobic OPPs
5.17
Equation of calibration curves, r2, LODs (for S/N = 3) on
160
the basis of peak areas and peak heights of three
hydrophobic OPPs in γ-CD-MEKC-SDS
5.18
Equation of calibration curves, r2, LODs (for S/N = 3) on
166
the basis of peak areas and peak heights of hydrophobic
OPPs in NM-MEKC-SC
5.19
RSD of migration time (min), peak height (mV) and peak
167
areas (mVs) of the separation of hydrophobic OPPs in
NM-MEKC-SC
5.20
Comparison of peak areas (mVs) and peak heights (mV) of
171
hydrophobic OPPs separated in NM-MEKC-SC and
stacking
5.21
LODs (ppm) of hydrophobic OPPs in all defined MEKC
175
methods (based on peak areas)
5.22
Analysis of three pesticides of hydrophobic OPPs spiked in
175
lake (Tasik UTM) water samples by sweeping-NM-MEKCSDS
6.1
Equation of calibration curves, r2, LODs (for S/N = 3) on
182
the basis of peak areas and peak heights of hydrophilic
OPPs separation in NM-MEKC
6.2
RSD of migration time (min), peak height (mV) and peak
183
areas (mVs) of the separation of hydrophilic OPPs in NMMEKC
6.3
Equation of calibration curves, r2, LODs (for S/N = 3) on
187
the basis of peak areas and peak heights of hydrophilic
OPPs separation in NSM
6.4
RSD of migration time (min), peak height (mV) and peak
189
areas (mVs) of the separation of hydrophilic OPPs in NSM
6.5
Sensitivity enhancements in NSM over NM-MEKC in the
separation of hydrophilic OPPs
193
xviii
6.6
Equation of calibration curves, r2, LODs (for S/N = 3) on
196
the basis of peak areas and peak heights of hydrophilic
OPPs separation in RM-MEKC
6.7
RSD of migration time (min), peak height (mV) and peak
198
areas (mVs) of the separation of hydrophilic OPPs in RMMEKC
6.8
Equation of calibration curves and r2 of the effect of
202
injection time or sample plug on peak areas of hydrophilic
OPPs in SRMM
6.9
Equation of calibration curves, r2, LODs (for S/N = 3) on
205
the basis of curves in Figure 6.26 A
6.10
RSD of migration time (min), peak height (mV) and peak
206
areas (mVs) of the separation of hydrophilic OPPs in
SRMM
6.11
Sensitivity enhancements in SRMM over RM-MEKC in
208
the separation of hydrophilic OPPs
6.12
Analysis of three hydrophilic OPPs spiked in lake (Tasik
UTM) water samples by SRMM
210
xix
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
2.1
Instrumental set-up of a capillary electrophoresis system
11
2.2
Longitudinal cross-section of a capillary in MEKC
13
2.3
Elution profile and corresponding peak shapes in HPLC
15
and CE
2.4
Structure of the two common surfactants used in MEKC
20
2.5
Chemical structure of β-CD with some characteristic
29
parameters
2.6
Focused sample zone by stacking in CZE
35
2.7
Focused sample zones by stacking in MEKC
36
2.8
Sweeping in a homogeneous electrical field with
38
negatively charged PS (e.g. SDS micelles) and a strong
EOF condition
3.1
Structure of the hydrophobic (A) and hydrophilic (B)
51
OPPs used in this study
4.1
Electropherogram of the separation of hydrophobic OPPs
60
in 10 mM phosphate (pH 9.3) and 20 mM SDS
4.2
Electropherogram of the separation of hydrophobic OPPs
60
in 40 mM phosphate (pH 9.3) and 20 mM SDS
4.3
Electropherogram of the separation of hydrophobic OPPs
61
in 60 and 80 mM phosphate (pH 9.3) and 20 mM SDS
4.4
Electropherogram of the separation of hydrophobic OPPs
61
in 30 mM phosphate (pH 9.3) and 60 mM SDS
4.5
Electropherogram of the separation of hydrophobic OPPs
in 10 mM phosphate (pH 9.3) and 10 mM SDS with 5 %
v/v acetonitrile
62
xx
4.6
Electropherogram of the separation of hydrophobic OPPs
65
in 5 mM borate buffer (pH 9.3), 10 mM SDS and 5 % v/v
methanol
4.7
Electropherogram of the separation of hydrophobic OPPs
66
in 10 mM phosphate buffer (pH 9.3), 10 mM SDS and 5
% v/v methanol
4.8
Electropherogram of the separation of hydrophobic OPPs
66
in 20 mM phosphate buffer (pH 9.3), 10 mM SDS and 5
% v/v methanol
4.9
Effect of phosphate buffer concentration on peak height
67
(A), peak areas (B) and efficiency (C) on separation of
hydrophobic OPPs
4.10
Effect of phosphate buffer concentration on the migration
69
time of hydrophobic OPPs
4.11
Electropherogram of the separation of hydrophobic OPPs
71
in 10 mM mixed buffer (phosphate + borate 1:1) (pH
9.3), 10 mM SDS and 5 % v/v methanol
4.12
Electropherogram of the separation of hydrophobic OPPs
71
in 20 mM mixed buffer (phosphate + borate 1:1) (pH
9.3), 10 mM SDS and 5 % v/v methanol
4.13
Effect of mixed buffer concentration on peak height (A),
72
peak areas (B) and efficiency (C) on separation of
hydrophobic OPPs
4.14
Effect of mixed buffer concentration on migration time of
74
hydrophobic OPPs
4.15
Comparison of phosphate and mixed buffer in relation to
76
peak heights (A), peak areas (B), efficiency (C), and
migration time (D) for the separation of hydrophobic
OPPs
4.16
Electrophoretic mobility of hydrophobic OPPs and the
EOF at four different levels of phosphate (•) and mixed
(□) buffer
77
xxi
4.17
Relationship between current generations in a range of
78
concentration of three separation buffers for the
separation of hydrophobic OPPs
4.18
Electropherogram of the separation of hydrophobic OPPs
82
in 10 mM mixed buffer (pH 9.3), 10 mM SDS and 10 %
v/v acetonitrile
4.19
Electropherogram of the separation of hydrophobic OPPs
82
in 10 mM mixed buffer (pH 9.3), 10 mM SDS and 10 %
v/v 2-propanol
4.20
Electropherogram of the separation of hydrophobic OPPs
83
in 10 mM mixed buffer (pH 9.3), 10 mM SDS and 5 %
v/v acetonitrile
4.21
Electropherogram of the separation of hydrophobic OPPs
83
in 10 mM mixed buffer (pH 9.3), 10 mM SDS and 5 %
v/v 2-propanol
4.22
Electropherogram of the separation of hydrophobic OPPs
84
in 10 mM mixed buffer (pH 9.3), 10 mM SDS and 10 %
v/v methanol
4.23
Effect of methanol levels on peak height (A), peak areas
85
(B), efficiency (C) and resolution of two peak pairs (D)
on separation of hydrophobic OPPs
4.24
Effect of methanol level on migration time of
87
hydrophobic OPPs
4.25
Electropherogram of the separation of hydrophobic OPPs
88
in 10 mM mixed buffer (pH 9.3), 10 mM SDS and 10 %
v/v mixed modifier (methanol and acetonitrile 1:1)
4.26
Electropherogram of the separation of hydrophobic OPPs
89
in 10 mM mixed buffer (pH 9.3), 10 mM SDS and 12.5
% v/v mixed modifier (methanol and acetonitrile 1:1)
4.27
Effect of modifier level on peak height (A), peak areas
(B), efficiency (C) and resolution of two peak pairs (D)
on separation of hydrophobic OPPs
90
xxii
4.28
Effect of mixed modifier levels on migration time of
91
hydrophobic OPPs
4.29
Comparison of methanol and mixed modifier in relation
93
to peak heights (A), peak areas (B), efficiency (C) and
resolution (D)
4.30
Comparison of methanol and mixed modifier in relation
94
to migration times
4.31
Electrophoretic mobility of hydrophobic OPPs and the
95
EOF at the four different levels of methanol (•) and
mixed (□) modifier
4.32
Electropherogram of the separation of hydrophobic OPPs
99
in 10 mM mixed buffer (pH 9.3), 10 mM SDS and 10 %
v/v mixed modifier (methanol and acetonitrile 1:1 v/v)
4.33
Electropherogram of the separation of hydrophobic OPPs
100
in 1 order lower concentration of each OPPs
4.34
Comparison of three sample matrixes in relation to peak
101
heights (A), peak areas (B), efficiency (C) and resolution
(D)
4.35
Effect of sample injection time in hydrodynamic mode
104
for the separation of hydrophobic OPPs
4.36
Effect of sample injection time in electrokinetic mode for
104
the separation of hydrophobic OPPs
4.37
Comparison between hydrodynamic (A) and
105
electrokinetic (B) sample injection for the separation of
hydrophobic OPPs
4.38
Effect of hydrodynamic (HD) and electrokinetic (EK)
105
sample injection for the same length of time (10 s) on
efficiency (A) and the resolution (B) of two last eluting
peak pairs in the separation of hydrophobic OPPs
4.39
Effect of detection wavelength in the range of 200 to 215
nm on peak heights (A) and peak areas (B) of
hydrophobic OPPs
107
xxiii
4.40
A pictorial sum up of the whole step-down optimization
110
procedures carried out for the hydrophobic OPPs
4.41
Separation of hydrophobic OPPs in a MEKC method
113
4.42
Effects of applied potentials on migration time of the
114
hydrophobic OPPs
4.43
Relationship between the coefficient values of the power
115
regression lines and the log value of k
4.44
Separation of hydrophilic OPPs in a MEKC method
116
4.45
Effects of applied potential on migration time of
117
hydrophilic OPPs
4.46
Relationship between log k and mean log Kow
120
5.1
Separations of hydrophobic OPPs with their various
125
concentrations in mixture by NM-MEKC-SDS
5.2
Electropherogram of replicated runs for the separation of
128
hydrophobic OPPs in NM-MEKC-SDS
5.3
Variations in N in the concentration range of hydrophobic
129
OPPs used in the calibration studies in NM-MEKC-SDS
5.4
Resolution of two peak pairs in the concentration range of
130
OPPs used in the calibration studies in NM-MEKC-SDS
5.5
Stacking in NM-MEKC-SDS for the separations of
132
hydrophobic OPPs by electrokinetic injection of sample
5.6
Stacking in NM-MEKC-SDS for the separations of
133
hydrophobic OPPs by injecting the sample
hydrodynamically
5.7
Sweeping in NM-MEKC-SDS for the separations of
135
hydrophobic OPPs
5.8
Separations of hydrophobic OPPs with their various
136
concentrations in mixture by sweeping-NM-MEKC-SDS
5.9
Electropherogram of replicated runs for the separation of
138
hydrophobic OPPs in sweeping-NM-MEKC-SDS
5.10
Sweeping in NM-MEKC-SDS for the separations three
141
hydrophobic OPPs
5.11
Separations of hydrophobic OPPs by RM-MEKC-SDS
145
xxiv
5.12
Separation of three hydrophobic OPPs by RM-MEKC-
146
SDS
5.13
RM-MEKC-SDS separations of three hydrophobic OPPs
147
with their various concentrations in mixture
5.14
Stacking in RM-MEKC-SDS for the separations of three
149
hydrophobic OPPs
5.15
Sweeping in RM-MEKC-SDS for the separations of
151
quinalphos and chlorpyrifos of hydrophobic OPPs
5.16
Sweeping in RM-MEKC-SDS for the separations of
152
quinalphos and profenofos of hydrophobic OPPs
5.17
Sweeping in RM-MEKC-SDS for the separation of
154
diazinon and quinalphos of hydrophobic OPPs
5.18
Separation of hydrophobic OPPs with β-cyclodextrin in
156
NM-MEKC-SDS (β-CD-MEKC-SDS)
5.19
Separation of hydrophobic OPPs with various level of γ-
157
cyclodextrin in NM-MEKC-SDS
5.20
Separation of hydrophobic OPPs with selected level of γ-
158
cyclodextrin in NM-MEKC-SDS (γ-CD-MEKC-SDS)
5.21
Separation of three hydrophobic OPPs in γ-CD-MEKC-
159
SDS
5.22
Sweeping and stacking in γ-CD-MEKC-SDS for the
161
separations of three hydrophobic OPPs
5.23
Separations of hydrophobic OPPs by NM-MEKC-SC
163
5.24
Peak identifications of hydrophobic OPPs in NM-MEKC-
164
SC against three single pesticide run
5.25
Separations of hydrophobic OPPs with their various
165
concentrations in mixture by NM-MEKC-SC
5.26
Electropherogram of replicated runs for the separation of
167
hydrophobic OPPs in NM-MEKC-SC
5.27
Variations in N in the concentration range of hydrophobic
168
OPPs used in the calibration studies in NM-MEKC-SC
5.28
Stacking in NM-MEKC-SC for the separations of
hydrophobic OPPs
170
xxv
5.29
Sweeping in NM-MEKC-SC for the separations of
172
hydrophobic OPPs
5.30
FESI in NM-MEKC-SC for the separations of
173
hydrophobic OPPs
5.31
Separation of three hydrophobic OPPs in spiked sample
176
with sweeping-NM-MEKC-SDS
6.1
Separations of hydrophilic OPPs by NM-MEKC
179
6.2
Peak confirmation of hydrophilic OPPs in NM-MEKC by
180
increasing the concentrations of one pesticide in mixture
at a time
6.3
Separations of hydrophilic OPPs with their various
181
concentrations in mixture by NM-MEKC
6.4
Electropherogram of replicated runs for the separation of
183
hydrophilic OPPs in NM-MEKC
6.5
Variations in N in the concentration range of hydrophilic
184
OPPs used in the calibration studies in NM-MEKC
6.6
Resolution of one peak pair in the concentration range of
184
pesticides used in the calibration studies in NM-MEKC
6.7
Separations of hydrophilic OPPs in NSM
186
6.8
Separations of hydrophilic OPPs with their various
187
concentrations in mixture by NSM
6.9
Electropherogram of replicated runs for the separation of
188
hydrophilic OPPs in NSM
6.10
Variations in N in the concentration range of hydrophilic
189
OPPs used in the calibration studies in NSM
6.11
Resolution of one peak pair in the concentration range of
190
pesticides used in the calibration studies in NSM
6.12
Electropherogram of effect of sample injection time in
191
NSM on resolution in the separation of hydrophilic OPPs
6.13
Effect of sample injection time in NSM on resolution in
191
separation of hydrophilic OPPs
6.14
Sensitivity enhancements in NSM over NM-MEKC in the
separation of hydrophilic OPPs
192
xxvi
6.15
Sensitivity improvements in NSM for two sample
193
matrices in separation of hydrophilic OPPs
6.16
Separations of hydrophilic OPPs by RM-MEKC
195
6.17
Separations of hydrophilic OPPs with their various
195
concentrations in mixture by RM-MEKC
6.18
Electropherogram of replicated runs for the separation of
197
hydrophilic OPPs in RM-MEKC
6.19
Variations in N in the concentration range of hydrophilic
198
OPPs used in the calibration studies in RM-MEKC
6.20
Resolution of one peak pair in the concentration range of
199
pesticides used in the calibration studies in RM-MEKC
6.21
Separations of hydrophilic OPPs in SRMM
200
6.22
Effect of sample injection (at 2.8 kPa) in SRMM on the
201
resolution of peaks
6.23
Effect of injection time or sample plug on peak areas (A)
202
and peak heights (B) of hydrophilic OPPs in SRMM
6.24
Effect of inadequate capillary flushing on migration times
203
and peak shapes in separation of hydrophilic OPPs by
SRMM
6.25
Separations of hydrophilic OPPs with their various
204
concentrations in mixture by SRMM
6.26
Calibration curves based on (A) peak areas and (B) peak
204
heights for the separation of hydrophilic OPPs in SRMM
6.27
Electropherogram of replicated runs for the separation of
206
hydrophilic OPPs in SRMM
6.28
Variations in N in the concentration range of hydrophilic
207
OPPs used in the calibration studies in SRMM
6.29
Resolution of one peak pair in the concentration range of
207
pesticides used in the calibration studies in SRMM
6.30
Sensitivity enhancements in SRMM over RM-MEKC in
208
the separation of hydrophilic OPPs
6.31
Separation of hydrophilic OPPs in spiked sample by
SRMM
209
xxvii
LIST OF SYMBOLS
µA
-
Micro ampere
µeo
-
Electroosmotic mobility
µep
-
Electrophoretic mobility
µL
-
Micro liter
cm
-
Centimeter
k
-
Retention factor (capacity factor)
K
-
Distribution coefficient
Kow
-
Octanol/Water partition coefficient
kPa
-
Kilo Pascal
L
-
Liter
min
-
Minute
mL
-
Mili Liter
mM
-
Mili Molar
N
-
Efficiency
nL
-
Nano Liter
nm
-
Nano Meter
Rs
-
Resolution
s
-
Seconds
Sw
-
Water solubility
t0
-
Migration time EOF marker
tm
-
Migration time micelle marker
V
-
Voltage
veo
-
Electroosmotic velocity
vep
-
Electrophoretic velocity
ζ
-
diffused double layer potential
κ
-
Number of regression lines
xxviii
LIST OF ABBREVIATIONS
AcN
-
Acetonitrile
BBMA
-
Butyl acrylate-butyl methacrylate-methacrylic acid
BGE
-
Background electrolyte
BMHC
-
Buffer matrix higher concentration
BMLC
-
Buffer matrix lower concentration
Bor
-
Borate
bp
-
Boiling point
CD
-
Cyclodextrin
CE
-
Capillary electrophoresis
CGE
-
Capillary gel electrophoresis
Ch
-
Chlorpyrifos
CL
-
Confidence Limit
CMC
-
Critical micelle concentration
CZE
-
Capillary zone electrophoresis
DD
-
Distilled deionized
DF
-
Degree of Freedom
Dz
-
Diazinon
EC
-
Electro chromatography
EKC
-
Electrokinetic chromatography
EOF
-
Electro osmotic flow
FESI
-
Field enhanced sample injection
GC
-
Gas chromatography
HB
-
Hydrogen bond
HPLC
-
High performance liquid chromatography
ID
-
Internal diameter
IEF
-
Isoelectric focusing (CE)
xxix
ITP
-
Isotachophoresis (CE)
LC
-
Liquid chromatography
LIF
-
Laser-induced fluorescence
LSER
-
Linear salvation energy relationship
Me
-
Methanol
MEKC
-
Micellar electrokinetic chromatography
mp
-
Melting point
MRL
-
Maximum residue levels
MS
-
Mass spectrometry
Mt
-
Methidathion
MT
-
Metric Ton
MW
-
Molecular weight
NAHC
-
Nonaqueous higher concentration
NM
-
Normal mode
NSM
-
Normal stacking mode
OD
-
Outer diameter
OPPs
-
Organophosphorus pesticides
Ph
-
Phosphate
Pr
-
Profenofos
PS
Pseudostationary phase
PTFE
-
Polytetrafluorethane
Qu
-
Quinalphos
RM
-
Reverse mode
SC
-
Sodium Cholate
SDS
-
Sodium dodecyl sulphate
SEF
-
Sensitivity enhancement factor
SRMM
-
Stacking reverse migrating micelles
SS
-
Sum of Squares
UTM
-
Universiti Teknologi Malaysia
UV
-
Ultraviolet
VIS
-
Visible
xxx
LIST OF APPENDICES
APPENDIX
A
TITLE
Consumption of OPPs in Four
PAGE
233
Representative Countries in the World
B
Basic and Relevant Information of OPPs
234
Used in These Studies
C
Tables of Statistical Comparison
243
Tests(Paired t-test) of Peak Parameters
D
Electropherograms of the Effect of
250
Detection Wavelengths on the
Separation of Hydrophobic OPPs
E
Estimation of Log Kow of Hydrophobic
251
OPPs Based on KOWWIN Program
(version 1.66) by Syracuse Research
Corporation of USA
F
Publications from This Study Program
256