behaviour of chlorpropham and its main metabolite 3-chloroaniline in soil and water systems

1

BEHAVIOUR OF CHLORPROPHAM AND ITS MAIN
METABOLITE 3-CHLOROANILINE IN SOIL AND
WATER SYSTEMS


BANDAR RASHED M. ALSEHLI
BSc., King Abdulaziz University, Saudi Arabia, 2004
MSc., Loughborough University, United Kingdom, 2009


Thesis submitted for the degree of
Doctor of Philosophy
February 2014


University of Glasgow
College of Science and Engineering
Department of Chemistry
Environmental, Agricultural and Analytical Chemistry Section





© ALSEHLI, B. R. M (2014)

2
Abstract
Chlorpropham, also known as isopropyl-N-(3-chlorophenyl) carbamate or CIPC is

a sprout suppressant and plant growth regulator of the chemical class derived
from carbamic acid (NH
2
COOH). The substance was first developed as a pre-
emergence herbicide, and it was quickly identified as a useful potato sprout
suppressant for long-term tuber storage (Marth & Schultz 1952). Today CIPC is
the major sprout inhibitor used in the potato industry (UK Potato Council 2013c).
As a consequence there is environmental concern about CIPC reaching the
aquatic environment from potato washing plants.
An RP-HPLC method for the analysis of CIPC and IPC in methanol solvent with an
automatic integration method was developed and validated. The correlation
coefficients for CIPC and IPC regression lines at all calibration levels (0.001–100
mg/L) were (R
2
>0.999) while IPC exhibited a slightly less linear calibration curve
(R
2
>0.98) at the lowest concentration range of (0.001–0.1 mg/L). An acceptable
precision of 10% based on 10 injections was obtained at the limit of
quantification of 0.001 mg/L for both analytes. The 3CA was excluded at this
stage as it overlapped with an extra peak which required extensive
investigations. The identification led to the conclusion that the artefact peak
was a methanol-oxygen peak and elimination of the methanol-oxygen peak was
not possible. The evaluation of five different columns and conditions in
separating the methanol-oxygen peak from 3CA in a mixture containing 3CA, IPC
and CIPC was studied. For the four peaks, the best separation at low eluant
concentration was obtained at 55% methanol, but the run time was considerable.
In contrast, the best separation at high eluant concentration was obtained at
75% methanol; however, the methanol-oxygen peak was still incompletely
separated from the IPC peak due to the high size of the methanol-oxygen peak.

Further investigations were conducted to reduce the size of the methanol-
oxygen peak by changing the mobile phase pH which had no effect. Changing
detection wavelength from 210 – 260 nm reduced the peak size, but considerable
loss in sensitivity was observed. Five different instruments were tried and at the
end the Thermo HPLC system was chosen because it provided a smaller
methanol-oxygen peak along with temperature control to enhance the methanol-
3
oxygen and 3CA peak separation at 60% methanol eluant, but the run time was
still very long. Therefore, to enable a compromise between baseline peak
resolutions as well as high-throughput separations; two separate methods for
3CA and CIPC, including IPC were developed and validated. The precision for
both analytes at two levels of 0.01 and 1.0 mg/L based on 10 injections was ≤
1%, the calibration curves at all levels were (R
2
>0.999) and the limit of
quantification was 0.001 mg/L. Preparation of CIPC, IPC and 3CA standards in
water from stock solutions in methanol and directly by dissolution in water was
investigated. The peak areas were not affected even at 0% methanol
concentration and the peak shapes were sharper than that in methanol without
affecting the peak area. This validated the use of water as sample solvent to
carry out the analysis by HPLC.
To successfully prepare CIPC, IPC and 3CA in 100% water, it was necessary to
develop methods for preparation and handling aqueous solution of CIPC, IPC and
3CA. The solubility of CIPC and IPC were studied. Both CIPC and IPC have low
solubility in water while 3CA has higher solubility and dissolved quite rapidly.
The solubility time curve for CIPC showed a gradual concentration increase from
initial time until day 3 stirring but after that the solubility was consistent and
values of 106, 89 and 61 mg/L CIPC were obtained at 25°C, 22°C and 4°C
respectively. IPC exhibited similar solubility behaviour and the corresponding
values were found to be 222, 200 and 140 mg/L at same temperatures

respectively. The solubility results agreed with the literature values. Stock
solutions and standards in aqueous solution were found to be stable on storage
at 4°C (refrigerator) and ~20°C (lab temperature) for up to 90 days. For this
work it was necessary to investigate possible CIPC, IPC and 3CA adsorption from
aqueous solutions by glassware and filters. All plastic glassware were avoided as
they have measurable adsorption (20-40%) for the analytes, except high clarity
polypropylene. In contrast, glass materials particularly borosilicate and soda
glass provided nearly zero adsorption for all three analytes. Although it was
possible to identify suitable glassware that did not adsorb CIPC, IPC and 3CA it
was necessary to discard the first 25 mL of filtrate to overcome adsorption onto
filters (Cellulose, Glass microfiber, PTFE and Nylon). The Glass microfiber, type
GF/B filter, has a pore size of 1.0 µm and is often used as a prefilter. However,
4
the 25 mL discarding from filtrate was suitable only for filtering sample larger
than 25 mL. For small scale filtration, a much smaller 0.2 µm PTFE filter in a 17
mm chemically resistant polypropylene housing disk attached to 3 mL BD syringe
was used and only 1.5 mL of the sample was required to saturate the filter.
A liquid-liquid extraction method with vortex mixer (LLE-Vortex) was
successfully developed and validated for the extraction of CIPC and 3CA from
dilute soil–water suspensions (0.001 g/mL) with a high recovery 98%–100% and
RSD% less than 1.34%. In addition, the method was reliable for extraction from
high soil suspensions formed with 0.02 g/mL of soil and for 0.1 g/mL of soils with
low adsorption capacity. The average precision of extracting CIPC at 0.02 g/mL
and 0.1 g/mL soil content was 1.6% and 3.2% while more precise extraction
observed for 3CA of about 0.91% and 1.86%, respectively. However, the
extraction method did not work for soil suspension with the highest organic
matter content and concentration equal or more than 0.1 g/mL.
Investigations were carried out to examine the adsorption- desorption behaviour
of CIPC and 3CA from aqueous solutions onto different clay and sandy air dried
soils. The suitable contact time of two days using 1 g material size was

determined. At all temperatures, CIPC and 3CA were strongly adsorbed in clay
soils while only slightly adsorbed in sandy soils. A paired t-test was used to
compare between the adsorption at 5°C and 30°C for CIPC and 3CA and
concluded that there was a statistically significant difference between the two
temperatures for both analytes (p-value < 0.05). The effect of pH was also
studied and it was found that the soil pH had a negligible impact on the
adsorption of CIPC, while for 3CA the adsorption at low and high pH was
significant (p-value <0.05). The data was fitted to a Langmuir isotherm (R
2
=0.91-
0.98) and adsorption maxima calculated. The maximum adsorption capacities for
CIPC in Downholland 1A, Downholland 2A, Midelney 2A, Midelney 1A, Midelney
1B, Dreghorn 1A, Dreghorn 1B, Quivox A and Quivox B were 1583, 668, 714, 927,
215, 325, 243, 355 and 194 µg/g respectively and for 3CA were 1024, 1104, 550,
651, 292, 278, 317, 239 and 162 µg/g respectively. The main determining factor
was soil organic matter. Desorption for CIPC and 3CA from soils increased with
reducing both carbon and LOI percentage. In addition, investigations were
extended to study the adsorption of CIPC and 3CA in oven dried plant waste
5
materials. The data was also fitted to a Langmuir isotherm (R
2
=0.96-1.00) and
adsorption maxima calculated. The maximum adsorption capacities for CIPC in
mixed bark, B&Q garden peat, Miracle-Gro compost, Pine needles, Scots pine
bark and Birch bark were 3090, 2968, 2973, 3636, 3004 and 2581 µg/g
respectively and for 3CA were 2914, 2724, 2953, 2787, 2358 and 2568 µg/g
respectively.
The removal of chlorpropham from two river water types was studied in
laboratory incubation experiments at two temperatures and different treatments
of carbon, nitrogen, phosphorus, Fulvic acid and soil extracts. The percentage of

a 10 mg/L addition of CIPC degraded over 40 days at 20°C in both River Kelvin
water and Glazert Water water was less than 2% in all the treatments. Increasing
the river water incubation temperature to 30°C resulted in a slight increase in
the degradation rate after 40 days. No 3CA intermediate from the 10 mg/L CIPC
spike was detected in any of the treatments of both the rivers.
CIPC removal from potato washing plant effluent (PWPE) was studied to
determine the rate of CIPC degradation. CIPC completely removed after the first
day with no detectable 3CA formation. A second incubation experiment for
PWPE removal was repeated after four months storage of the effluent at 4°C.
The result of CIPC removal showed a small initial drop about 14% within one day
which might be interpreted as adsorption followed by a steady line with no
further change in the concentration during the 22 days of incubation. It is
suggested that the cold storage killed off the bacteria and reduced the
decomposition process. Thus, having established that the microbial degradation
was the predominant process with the fresh PWPE, the degradation kinetic order
needs to be determined. The analysis of degradation kinetics shows that the
process corresponds to a first order model (R
2
=0.99) and the degradation rate
was calculated to be 2.0 days
−1
. The half-life was 0.36 day.
CIPC removal from synthetic potato wash water (SPWW) was studied to
determine the rate of CIPC degradation. CIPC completely disappeared after 1.2
days with no detectable 3CA formation. An identical incubation experiment for
SPWW was repeated after four months for potato tubers stored at 4°C. The
slowing of degradation might be explained by stressing of the potato surface‘s
6
bacteria due to the change from cold storage to 20°C causing one population to
die and another to develop. Thus having established that the microbial

degradation was the predominant process with the fresh SPWW, the degradation
kinetic order needs to be determined. The analysis of degradation kinetics shows
that the process corresponds to a zero order model (R
2
=0.98) and the
degradation rate was calculated to be 7.3 mg/L/day.
CIPC removal from suspensions of potato materials can be summarised as
follows: CIPC adsorption process of potato materials lasts 1 day; it continues on
the secondary adsorbent (starch) accompanied by slow microbial degradation
and gradual microbial population growth. Finally, microbial degradation finishes
the process with a sharp decrease of CIPC concentration. The 3CA intermediate
from CIPC spike was undetected.
The clarified synthetic potato washing water experiment supported the
argument that the aim of excluding adsorption from the system worked and only
the decomposition process was observed. The 1 h sedimentation is sufficient to
achieve removal of adsorption surfaces and the longer sedimentation time
results in losses of decomposed microorganisms.
Overall, the removal results suggested that there are two separate populations
i.e. CIPC decomposers and 3CA decomposers. CIPC decomposing microorganisms
and 3CA decomposing microorganisms are present in the effluent from the
potato washing plant and on the surfaces or the soils of CIPC treated potatoes
but not in the river water samples. The numbers of CIPC and 3CA decomposing
organisms decline on storage of the potatoes and the effluent at 4°C. In
addition, CIPC decomposition is inhibited by the addition of nutrients. However,
these removal studies were based on filtration. Thus, to enable the amount
adsorbed in soil suspensions to be measured and the microbial degradation rate
to be accurately evaluated, the application of (LLE-Vortex) for the simultaneous
extraction of CIPC and 3CA from soil-water system was necessary.
The microbial degradation of 10 mg/L CIPC and 10 mg/L 3CA at 20°C in the
freshly prepared SPWW was simultaneously measured by PTFE filtration and LLE-

Vortex methods to compare the methods. The 3CA intermediate as a result of
7
CIPC degradation was also included. The results showed that the degradation
curves were similar for both analytical methods as the soil coating the potato
tubers was very sandy and when the washes were generated in 2 L flasks and
diluted, the content of soil in the suspension became negligible. The microbial
degradation of CIPC in SPWW was linear from start to the end with zero order
degradation rate of 2.11 mg/L/day. 3CA intermediate reached a maximum of 1.5
mg/L after day 1, and then degraded. The 10 mg/L 3CA degradation was curved
thus initial and final straight lines were fitted and the zero order degradation
rates were found to be 0.74 and 2.82 mg/L/day, respectively. The degradation
for all was observed to be complete in less than one week.
The incubation experiment at 20°C was repeated with the addition of 100 mg/L
CNP nutrients from glucose, ammonium sulphate and monopotassium phosphate
to the spiked SPWW. The addition of CNP nutrients suppressed 10 mg/L CIPC
degradation and slightly delayed 10 mg/L 3CA degradation. The 3CA
intermediate was not detected. The CIPC degradation rate calculation was
impractical as 8 mg/L CIPC still remained in the suspension after 26 days and it
was time dependent. The degradation rate of 10 mg/L 3CA after the two days
lag period was fitted and the zero order degradation rate of 3.36 mg/L/day was
determined. Degradation was observed to be complete for 10 mg/L 3CA sample
in less than one week which was similar to the unfortified finishing time.
The SPWW suspension was incubated at four different temperatures of 5°C,
10°C, 15°C and 20°C to study the impact of these temperatures on the
degradation rate. The degradation of 10 mg/L CIPC increased with temperature
with no lag phases; straight lines were plotted and the zero-order degradation
rates were calculated as 0.52, 1.21, 1.83 and 2.13 mg/L/day at 5°C, 10°C, 15°C
and 20°C respectively. Analysis of 3CA intermediate formation shows that CIPC
samples incubated at different temperatures demonstrated different 3CA
formation trends and some of them reached 3.5 mg/L. In contrast, the initial

degradation rates of 10 mg/L 3CA at 5°C and 10°C could not be detected and
the final rates were linear. At 15°C and 20°C the graph was curved, forming an
inconsistent trend between the initial and final stages. Thus, at 5°C and 10°C
the final rates were 0.28 and 0.53 mg/L/day respectively. At 15°C and 20°C the
initial rates were 0.35 and 0.71 mg/L/day, while final rates were 3.82 and 3.52
8
mg/L/day respectively. Incubation of SPWW at different temperatures provided
an activation energy value of 63 kJ/mol for CIPC while the activation energy for
3CA based on initial and final rates were 99 and 130 kJ/mol, respectively.
Fresh soils that had no history of CIPC application contained CIPC and 3CA
degraders but they took 1–3 weeks to start. The degradation was linear and zero
order degradation rates were calculated for CIPC (4.20, 2.11, 2.62 mg/L/day)
and 3CA (1.51, 2.62, 1.92 mg/L/day) in Darvel, Cottenham and Dreghorn 2A,
respectively.
Drying the soils killed bacteria but the suspension still contained small numbers
capable of degrading CIPC and 3CA after a long incubation period.











9
Table of Contents

Abstract 2
Acknowledgement 21
Author’s Declaration 22
List of Abbreviations 23

Chapter 1 - Main Introduction 25

1.1 Background related to the use of sprout suppressants in the potato industry 25
1.1.1 Current state of UK potato market 25
1.2 Potato storage 28
1.2.1 Chemical-free storage 28
1.2.2 Use of sprout suppressant chemicals 29
1.2.3 Toxicity of CIPC and its metabolites to humans 32
1.3 The environmental fates of CIPC and its metabolite 3CA 36
1.3.1 Environmental toxicity 36
1.3.2 Properties 37
1.3.3 Environmental fate of CIPC and 3CA 41
1.4 Analysis of CIPC and its metabolites in environmental samples 49
1.4.1 Extraction methods 49
1.4.2 Instrumental analysis 58
1.4.3 HPLC analysis 58
1.5 Validation of analytical method 75
1.5.1 Calibration linearity 77
1.5.2 Accuracy 79
1.5.3 Precision 80
1.5.4 Limit of detection and limit of quantification 80
1.6 Thesis objectives 84

Chapter 2 - RP-HPLC method development for chlorpropham, propham and 3-chloroaniline in
methanol 86

2.1 Introduction 86
2.2 Materials and methods 89

2.2.1 Analysis of CIPC and IPC in RP-HPLC Shimadzu system A 89
2.2.2 Separation of the methanol-oxygen peak from 3CA 91
2.2.3 Effect of detection wavelength 92
2.2.4 Effect of different HPLC systems on the appearance of the methanol-oxygen peak
92
2.2.5 Effect of temperature control on the separation of the four peaks at 60%
methanol in water 93

2.3 Results and discussion 94

2.3.1 Analysis of CIPC and IPC in RP-HPLC Shimadzu system A 94
2.3.2 Summary of CIPC and IPC analysis conditions by RP-HPLC Shimadzu system A 96
2.3.3 Identification of the unknown peak 100
2.3.4 Separation of the methanol-oxygen peak from 3CA 106
2.3.5 Effect of detection wavelength 110
2.3.6 Effect of different HPLC systems on the appearance of the methanol-oxygen peak
113
2.3.7 Effect of temperature control on the separation of the four peaks at 60%
methanol in water 117
2.3.8 3CA method 120
10
2.3.9 CIPC method 122

2.4 Conclusion 125

Chapter 3 - Development of methods for preparation and handling aqueous solutions of CIPC,

IPC and 3CA 126

3.1 Introduction 126
3.2 Materials and methods 129

3.2.1 CIPC, IPC and 3CA peak area comparisons 129
3.2.2 CIPC, IPC and 3CA standard preparation in 100% deionised water 131
3.2.3 CIPC, IPC and 3CA adsorption by labware 132
3.2.4 RP- HPLC measurement 134

3.3 Results and discussion 135

3.3.1 CIPC, IPC and 3CA peak area comparisons 135
3.3.2 CIPC, IPC and 3CA standard preparation in 100% deionised water 141
3.3.3 CIPC, IPC and 3CA adsorption by labware 147

3.4 Conclusion 168

Chapter 4 – Adsorption of CIPC and 3CA in soils and their economical removal by plant waste
materials 169

4.1 Introduction 169

4.1.1 Importance 169
4.1.2 Adsorption in soil 171
4.1.3 Adsorption in plant and other waste materials 173
4.1.4 Objective 178

4.2 Materials and methods 178

4.2.1 Adsorption and desorption of CIPC and 3CA in soil samples 178
4.2.2 Removal of CIPC and 3CA by plant and other waste materials 183
4.2.3 Calculation 185
4.2.4 HPLC determination 186
4.2.5 XLfit
®
software 186

4.3 Results and discussion 187

4.3.1 Chromatograms of CIPC and 3CA in soils and waste materials 187
4.3.2 Adsorption and desorption of CIPC and 3CA in soil samples 192
4.3.3 Removal of CIPC and 3CA by plant and other waste materials 212

4.4 Conclusion 226

Chapter 5 – Removal of chlorpropham from river and waste water 227

5.1 Introduction 227
5.2 Materials and methods 230

5.2.1 HPLC chromatographic method 230
5.2.2 Removal of CIPC from river water 230
5.2.3 Removal of CIPC from potato washing plant effluent 237
5.2.4 Removal of CIPC from synthetic potato washing water 237
11
5.2.5 Removal of CIPC from potato materials suspension 238
5.2.6 Removal of CIPC from clarified synthetic potato wash water 238
5.2.7 CIPC measurement in free solids samples 240
5.2.8 CIPC measurement in solids-water samples 240

5.3 Results and discussion 241

5.3.1 Representative chromatograms of CIPC in different environmental compartments
241
5.3.2 Removal of CIPC from river water 248
5.3.3 Removal of CIPC from potato washing plant effluent 254
5.3.4 Removal of CIPC from synthetic potato washing water 257
5.3.5 Removal of CIPC from potato materials suspension 261
5.3.6 Removal of CIPC from clarified synthetic potato wash water 264

5.4 Conclusion 269

Chapter 6 - Solvent extraction method development and application to degradation of CIPC
and 3CA 270

6.1 Introduction 270

6.1.1 Overview of liquid extraction methods for pesticides recovery 270
6.1.2 EPA methods for CIPC and other pesticides 271
6.1.3 Extraction improvement techniques 271
6.1.4 Choice of a solvent for LLE 272
6.1.5 Simultaneous separation of several compounds 273
6.1.6 Modifications of LLE extraction for the present study 273
6.1.7 LLE method for CIPC and 3CA simultaneous extraction 274

6.2 Materials and methods 275

6.2.1 HPLC chromatographic method 275
6.2.2 Materials 275

6.2.3 Extraction of CIPC and 3CA from deionised water by immiscible solvents using
separatory funnels 276
6.2.4 Extraction of CIPC and 3CA from deionised water by DCM using a LLE-VORTEX
method 277
6.2.5 Validation of the optimum LLE-VORTEX method in waste water 278
6.2.6 Application of LLE-Vortex method to microbial degradation of CIPC and 3CA in
synthetic potato wash water and soil suspensions 280

6.3 Results and discussion 282

6.3.1 Extraction of CIPC and 3CA from deionised water by immiscible solvents using
separatory funnels 282
6.3.2 Extraction of CIPC and 3CA from deionised water by DCM using a LLE-VORTEX
method 286
6.3.3 Summary of the optimum LLE-VORTEX method for simultaneous extraction of
CIPC and 3CA from deionised water 288
6.3.4 Validation of the optimum LLE-VORTEX method in waste water 289
6.3.5 Summary on method development 298
6.3.6 Application of LLE-Vortex method to microbial degradation of CIPC and 3CA in
synthetic potato wash water and soil suspensions 299

6.4 Conclusion 325



12
Chapter 7 – General discussion 326

7.1 Summary of experiments 326
7.2 Implications of the work 335

7.2.1 CIPC application 335
7.2.2 Storage 337
7.2.3 Washing water 337
7.2.4 Recommendations for future research 344
7.2.5 Recommendations for the potato processing industry 348

References 352
Publications 374













13
List of Tables
Table 1.1 - The detected residues in potato samples in the period 2000-2012. Adapted from
Pesticide Residues in Food, PRiF (2013) 35
Table 1.2 - Chlorpropham identification, physico-chemical and environmental properties. 38
Table 1.3 - Propham identification, physico-chemical and environmental properties. 39
Table 1.4 - 3-chloroaniline identification, physico-chemical and environmental properties. 40
Table 1.5 - Sample preparation techniques. Adapted from Beyer & Biziuk (2008). 50

Table 1.6 - Assessment of the linearity of a HPLC method. 78

Table 2.1 - Five different columns used in developing and separating the four peaks of 3CA,
methanol-oxygen peak, IPC and CIPC. 91
Table 2.2 - LOD and LOQ based on 10 injections from three concentration levels. 100
Table 2.3 - LOD and LOQ based on the lowest calibration curve (0.001 – 0.1 mg/L). 100
Table 2.4 - Peak areas of the unknown peak at different injection treatments using the
Shimadzu A system with degassed 72% methanol eluant, 210 nm, 1 mL/min flow
rate, Nemesis column at lab temperature, approx. 20°C. The injection solvent
was a subsample from the mobile phase. 103
Table 2.5 - HPLC Detectors accuracy and Bandwidth. 116
Table 2.6 - System precision based on 10 injections from 0.01 and 1.0 mg/L 3CA in methanol. 120
Table 2.7 - LOD and LOQ based on 10 injections from 0.01 and 1.0 mg/L 3CA in methanol. 122
Table 2.8 - System precision based on 10 injections from 0.01 and 1.0 mg/L CIPC in methanol. 123
Table 2.9 - LOD and LOQ based on 10 injections from 0.01 and 1.0 mg/L CIPC in methanol. 124

Table 3.1 - Filter papers description. 133
Table 3.2 - Solubility of CIPC in deionised water based on the mean of days 4-16. 142
Table 3.3 - Solubility of IPC in deionised water based on the mean of days 4-16 144
Table 3.4 - Stability of stock and standard solutions at 4°C and 20°C. 146
Table 3.5 - Recovery of 1.00 and 0.05 mg/L CIPC standards in deionised water from different
containers. 149
Table 3.6 - Recovery of 1.00 and 0.05 mg/L IPC standards in deionised water from different
containers. 150
Table 3.7 - Recovery of 1.00 and 0.05 mg/L 3CA standards in deionised water from different
containers. 151
Table 3.8 - Recovery of 1.00 and 0.05 mg/L CIPC standards in deionised water from different
stoppers. 152
Table 3.9 - Recovery of 1.00 and 0.05 mg/L IPC standards in deionised water from different
stoppers. 153

Table 3.10 - Recovery of 1.00 and 0.05 mg/L 3CA standards in deionised water from different
stoppers. 154
Table 3.11 - Recovery of 1.00 and 0.05 mg/L CIPC standards in deionised water from different
syringes. 155
Table 3.12 - Recovery of 1.00 and 0.05 mg/L IPC standards in deionised water from different
syringes. 155
14
Table 3.13 - Recovery of 1.00 and 0.05 mg/L 3CA standards in deionised water from different
syringes. 155

Table 4.1 - Soil characteristics (Khan 1987; Bakhsh 1988; Mazumder 1992; Amin 1995). 180
Table 4.2 - Soil characteristics (Khan 1987; Bakhsh 1988; Mazumder 1992; Amin 1995). 181
Table 4.3 - Literature values for proximate composition of plant materials used in the study. . 184
Table 4.4 - Description of composts used in the study. 184
Table 4.5 - Clay materials and descriptions. 184
Table 4.6 - The maximum adsorption capacity (Xmax) of CIPC and 3CA in soils. 204
Table 4.7 - Percentage of CIPC and 3CA desorption from clay and sandy soils. 210
Table 4.8 - The maximum adsorption capacity (Xmax) of CIPC and 3CA in waste materials. 222

Table 5.1 - Nutrients properties. 232
Table 5.2 - Different concentration of clarified supernatant. 239
Table 5.3 - The acidity of the potato washing plant effluent. 255
Table 5.4 - Kinetic analysis of the removal process from the fresh PWPE suspension. 255
Table 5.5 - The acidity of synthetic potato washing water. 258
Table 5.6 - Kinetics analysis of the removal process from fresh SPWW suspension 259
Table 5.7- Characterization of CIPC degradation at various potato materials 262

Table 6.1 - Properties of organic immiscible solvents. 275
Table 6.2 - Characteristics of two rotary evaporators. 276
Table 6.3 - Soil characteristics (Khan 1987; Mazumder 1992; Amin 1995). 279

Table 6.4 - Extraction with ethyl acetate at different pH and in presence of sodium chloride. . 285
Table 6.5 - Extraction by dichloromethane from deionised water. 286
Table 6.6 - Primarily extraction of CIPC and 3CA from deionised water by LLE-VORTEX. 287
Table 6.7 - Optimum extraction of CIPC and 3CA from deionised water by LLE-VORTEX 287
Table 6.8 - Validation of CIPC and 3CA extraction from dilute waste water. 296
Table 6.9 - Zero-order rate constants of 10 mg/L CIPC in unfortified SPWW at 20°C. 302
Table 6.10 - Degradation rate constant of 10 mg/L 3CA in unfortified SPWW at 20°C. 303
Table 6.11 - Degradation rate constant of 10 mg/L 3CA in fortified SPWW at 20°C. 306
Table 6.12 - Degradation rate constant of 10 mg/L CIPC at different temperatures. 309
Table 6.13 - Degradation rate constant of 10 mg/L 3CA at different temperatures. 310
Table 6.14 - pH values of the incubated SPWW at different temperatures. 312
Table 6.15 - Degradation rate constants of 10 mg/L CIPC in soil suspensions. 320
Table 6.16 - Degradation rate constants of 10 mg/L 3CA in soil suspensions. 321
Table 6.17 - The pH changes in the incubated three soil suspensions. 321

15
Lists of Figures
Figure 1.1 - Consumption of carbohydrate meal occasions. Data adapted from UK Potato
Council (2013a). 25
Figure 1.2 - Consumption of carbohydrate meal occasions. Data adapted from UK Potato
Council (2013a). 26
Figure 1.3 - Potato production flowchart for Great Britain for June 2011 to May 2012. Taken
from Potato Council website (UK Potato Council 2013b). 27
Figure 1.4 - CIPC fate in environment. Adapted from Führ (1991). 41
Figure 1.5 - CIPC degradation (blue line) and microbial population (red line) profiles for
primary (a) and secondary (b) metabolism (Linde 1994). 48
Figure 1.6 - HPLC scheme (Snyder, Kirkland & Dolan 2010). 59
Figure 1.7 - (a) Peak asymmetry and tailing factors definitions (A
S
and TF); (b) peak shape of

(A
S
and TF); (c) peak tailing effect on separation; (d) fronting; (e) overloaded
tailing (Snyder, Kirkland & Dolan 2010). 66
Figure 1.8 - Influence of k, N and α on resolution (Ahuja 2003). 68
Figure 1.9 - Van Deemter curve presenting the relationship between HETP and average
linear velocity. The Vopt = optimum velocity; Hmin = minimum plate height
(Dong 2006). 70
Figure 1.10 - HPLC chromatogram for pesticides analysis (Environmental Protection
Agency 2006b). Column: Ascentis column C18, 250 mm x 4.6 mm, 5 μm.
Mobile phase: (%A) water, (%B) acetonitrile. Column temperature: 30 °C. UV
detection: 210 nm. Flow rate: 1.0 mL/min. Samples were prepared in 16%
acetonitrile in water with an injection volume of 10 μL. 74
Figure 1.11 - HPLC chromatogram for CIPC (David et al. 1998). 74
Figure 1.12 - Calibration line of peak area versus concentration of an analyte. 79

Figure 2.1 - Analysis of 3CA, IPC and CIPC using the Shimadzu A system with degassed 72%
methanol eluant, 210 nm, 1 mL/min flow rate, Nemesis column at lab
temperature, approx. 20°C. The standard was a 1 mg/L 3CA, IPC and
CIPC in methanol. Peaks 1, 2,3 and 4 were 3CA, unknown peak, IPC and CIPC,
respectively. 94
Figure 2.2 - Analysis of IPC and CIPC using the Shimadzu A system with degassed 68%
methanol eluant, 210 nm, 1 mL/min flow rate, Nemesis column at lab
temperature, approx. 20°C. The standard was a 1 mg/L IPC and CIPC in
methanol. Peaks 2, 3 and 4 were unknown peak, IPC and CIPC, respectively. 95
Figure 2.3 - Shimadzu LC-Solution software integration method. 97
Figure 2.4 - System precision at different concentration ranges for the analysis of IPC
and CIPC. 98
Figure 2.5 - Calibration curve for the high range (10 – 100 mg/L) of CIPC and IPC in
methanol. 99

Figure 2.6 - Calibration curve for the medium range (1 – 10 mg/L) of CIPC and IPC in
methanol. 99
Figure 2.7 - Calibration curve for the low range (0.001 – 0.1 mg/L) of CIPC and IPC in
methanol. 99
Figure 2.8 - Analysis of 3CA, IPC and CIPC using the Shimadzu A system with degassed 60%
acetonitrile eluant, 210 nm, 1.5 mL/min flow rate, Nemesis column at lab
temperature, approx. 20°C. The standard was a 1 mg/L 3CA, IPC and CIPC in
acetonitrile. Peaks 1, 3 and 4 were 3CA, IPC and CIPC, respectively. 102
16
Figure 2.9 - Peak areas of the unknown peak in 15 different methanol batches using the
Shimadzu A system with degassed 72% methanol eluant, 210 nm, 1 mL/min
flow rate, Nemesis column at lab temperature, approx. 20°C. The injection
solvent was a subsample from the mobile phase. 102
Figure 2.10 - Using the Shimadzu A system with 72% methanol eluant, 210 nm, 1 mL/min
flow rate, Nemesis column at lab temperature, approx. 20°C. A blank from
a mobile phase was 1) Inject without treatment, 2) Purged with air and
3) Degassed with Helium, using a) Degassed and b) Non-degassed mobile
phase at 210 nm. 104
Figure 2.11 - The effect of 72%-55% methanol eluant strengths on Nemesis column,
using the Shimadzu A system, 210 nm, and 1 mL/min flow rate at lab
temperature, approx. 20°C. The standard was a 1 mg/L 3CA, IPC and CIPC
in methanol. Peaks 1, 2, 3 and 4 were 3CA, methanol-oxygen peak, IPC and
CIPC, respectively. 106
Figure 2.12 - The effect of 72%-55% methanol eluant strengths on Columbus column,
operated at same conditions. 107
Figure 2.13 - The effect of 72%-55% methanol eluant strengths on Hypersil column,
operated at same conditions. 107
Figure 2.14 - The effect of 72%-55% methanol eluant strengths on a Spherisorb column,
operated at same conditions. 108
Figure 2.15 - The effect of 72%-55% methanol eluant strengths on a Sphereclone column,

operated at same conditions. 108
Figure 2.16 - The effect of 85%-72% methanol eluant strengths on Nemesis column, using
the Shimadzu A system, 210 nm, and 1 mL/min flow rate at lab temperature,
approx. 20°C. The standard was a 1 mg/L 3CA, IPC and CIPC in methanol.
Peaks 1, 2, 3 and 4 were 3CA, methanol-oxygen peak, IPC and CIPC,
respectively. 109
Figure 2.17 - The effect of 75% methanol eluant a) neutral and b) buffer using the
Shimadzu A system, 210 nm, 1 mL/min flow rate, Nemesis column at lab
temperature, approx. 20°C. The standard was a 1 mg/L 3CA, IPC and CIPC in
methanol. Peaks 1, 2, 3 and 4 were 3CA, methanol-oxygen peak, IPC and
CIPC, respectively. 110
Figure 2.18 - Effect of detection wavelength for analytes on Shimadzu A system at 72%
methanol using Nemesis column. Peaks 1, 2, 3 and 4 were 3CA,
methanol-oxygen peak, IPC and CIPC, respectively. 111
Figure 2.19 - UV spectrum for the four peaks using the Diode array detector, using
1 mg/L 3CA, IPC and CIPC standard in methanol. 112
Figure 2.20 - Shimadzu system A with manual injection. 114
Figure 2.21 - Shimadzu system A with autosampler injection. 114
Figure 2.22 - Shimadzu system B with manual injection. 114
Figure 2.23 - Thermo system with autosampler injection. 115
Figure 2.24 - Diode array with autosampler injection. 115
Figure 2.25 - The effect of 30°C column temperature on the separation of the four peaks
using the Thermo system with degassed 60% methanol eluant, 210 nm, and 1.5
mL/min flow rate. The standard was a 1 mg/L 3CA, IPC and CIPC in methanol.
Peaks 1, 2, 3 and 4 were 3CA, methanol-oxygen, IPC and CIPC, respectively. 118
Figure 2.26 - The effect of 25°C column temperature on the separation of the four peaks
using the Thermo system with degassed 60% methanol eluant, 210 nm, and 1.5
mL/min flow rate. The standard was a 1 mg/L 3CA, IPC and CIPC in methanol.
Peaks 1, 2, 3 and 4 were 3CA, methanol-oxygen, IPC and CIPC, respectively. 118

17
Figure 2.27 - The effect of 20°C column temperature on the separation of the four peaks
using the Thermo system with degassed 60% methanol eluant, 210 nm, and 1.1
mL/min flow rate. The standard was a 1 mg/L 3CA, IPC and CIPC in methanol.
Peaks 1, 2, 3 and 4 were 3CA, methanol-oxygen, IPC and CIPC, respectively. 119
Figure 2.28 - The effect of 20°C column temperature on the separation of the three peaks
using the Thermo system with degassed 60% methanol eluant, 210 nm,
and 1.1 mL/min flow rate. The standard was a 1 mg/L 3CA and IPC in
methanol. Peaks 1, 2 and 3 were 3CA, methanol-oxygen and IPC, respectively. . 120
Figure 2.29 - Calibration curve for (1 – 10 mg/L) 3CA in methanol. 121
Figure 2.30 - Calibration curve for (0.05 – 0.8 mg/L) 3CA in methanol. 121
Figure 2.31 - The effect of 33°C column temperature on the separation of the three peaks
using the Thermo system with degassed 70% methanol eluant, 210 nm,
and 1.4 mL/min flow rate. The standard was a 1 mg/L IPC and CIPC in
methanol. Peaks 2, 3 and 4 were methanol-oxygen, IPC and CIPC, respectively. 122
Figure 2.32 - Calibration curve for (1 – 10 mg/L) CIPC in methanol. 123
Figure 2.33 - Calibration curve for (0.05 – 0.8 mg/L) CIPC in methanol. 124

Figure 3.1 - IPC and CIPC peak shape in 100% methanol and 100% deionised water as
injection solvent. 136
Figure 3.2 - CIPC peak shape in 100% methanol and 100% deionised water as injection
solvent. 137
Figure 3.3 - 3CA peak shape in 100% methanol and 100% deionised water as injection
solvent. 138
Figure 3.4 - Comparison between the peak area of CIPC, IPC and 3CA in 1%, 5%, 20% and
100% methanol in deionised water. 140
Figure 3.5 - The solubility of CIPC in deionised water till day 16. 142
Figure 3.6 - The Solubility of IPC in deionised water till day 16. 143
Figure 3.7- Dissolving speed of 3CA in deionised water. 144
Figure 3.8 - Recovery of the 1st to 4th 5 mL aliquot of 1 mg/L standards in deionised

water passed through different types of filter papers. 158
Figure 3.9 - Recovery of five standards concentrations in ten sequential 5 mL aliquots
passed through No.1 filter paper. 160
Figure 3.10 - Recovery of five standards concentrations in ten sequential 5 mL aliquots
passed through GF/B filter paper. 161
Figure 3.11 - Recovery of five standards concentrations in ten sequential 5 mL aliquots
passed through PTFE filter paper. 162
Figure 3.12 - Recovery of five standards concentrations in ten sequential 5 mL aliquots
passed through Nylon filter paper 163
Figure 3.13 - Recovery based on averaging aliquots 6-10. 165

Figure 4.1 - Representative chromatograms of CIPC in soils at a concentration of 8.0 mg/L
by Shimadzu A system. 188
Figure 4.2 - Representative chromatograms of 3CA in soils at a concentration of 8.0 mg/L
by Thermo system. 189
Figure 4.3 - Representative chromatograms of CIPC in waste materials at a concentration
of 8.0 mg/L by Shimadzu A system. 190
Figure 4.4 - Representative chromatograms of 3CA in waste materials at a concentration
of 8.0 mg/L by Thermo system. 191
18
Figure 4.5 - 10 µg/mL CIPC and 3CA uptake within 30 days at 20°C and 30°C using 5g soil. 194
Figure 4.6 – 10 µg/mL CIPC and 3CA uptake in clay and sandy soils within four days at 20°C
using 1 g soil. 195
Figure 4.7 - Temperature effect on 10 µg/mL CIPC and 3CA adsorption. 196
Figure 4.8 - pH effect on 10 µg/mL CIPC and 3CA adsorption. 198
Figure 4.9 - Adsorption isotherm of CIPC and 3CA in clay and sandy soils at 20°C. 200
Figure 4.10 - Langmuir isotherm of CIPC in three soils. 202
Figure 4.11 - Langmuir isotherm of 3CA in three soils. 203
Figure 4.12 - CIPC experimental and theoretical adsorption isotherm for the three soils. 205
Figure 4.13 - 3CA experimental and theoretical adsorption isotherm for the three soils. 206

Figure 4.14 - CIPC and 3CA Xmax plotted against LOI in soils. 207
Figure 4.15 - CIPC and 3CA Xmax plotted against total carbon in soils. 207
Figure 4.16 - CIPC and 3CA desorption versus adsorption in clay soils at 20°C. The 3CA
desorption was not detected in Downholland 1A, Downholland 2A and
Midelney 2A. 209
Figure 4.17 - CIPC and 3CA desorption versus adsorption in sandy soils at 20°C. 209
Figure 4.18 - Correlation between desorption and loss on ignition for CIPC and 3CA. 211
Figure 4.19 - Correlation between desorption and total carbon for CIPC and 3CA. 211
Figure 4.20 - The adsorption% of 10 µg/mL CIPC and 3CA on different sorbents. 214
Figure 4.21 - Adsorption isotherm of CIPC and 3CA on waste materials. 218
Figure 4.22 - Langmuir isotherm of CIPC in three waste materials. 220
Figure 4.23 - Langmuir isotherm of 3CA in three waste materials. 221
Figure 4.24 - CIPC experimental and theoretical adsorption isotherm for three waste
materials. 223
Figure 4.25 - 3CA experimental and theoretical adsorption isotherm for three waste
materials. 224

Figure 5.1 - River Kelvin water sampling location, Glasgow, UK. 231
Figure 5.2 - Glazert Water water location, near Glasgow, UK. 231
Figure 5.3 - Extraction of organic matter and fractionation of Fulvic acid. 234
Figure 5.4 - Dissolved oxygen meter YSI Model 58 SN: 94 M27200. 236
Figure 5.5 - Representative chromatograms of CIPC in Kelvin River water, a) blank,
b) 10.0 mg/L CIPC. Analysed by Thermo system; CIPC method in section 2.3.9. . 242
Figure 5.6 - Representative chromatograms of CIPC in Glazert Water water, a) blank,
b) 10.0 mg/L CIPC. Analysed by Thermo system; CIPC method in section 2.3.9. . 243
Figure 5.7 - Representative chromatograms of CIPC in potato washing plant
effluent (PWPE), a) blank, b) 0.1 mg/L CIPC. Analysed by Thermo system;
CIPC method in section 2.3.9. 244
Figure 5.8 - Representative chromatograms of CIPC synthetic potato washing water
(SPWW), a) blank, b) 0.1 mg/L CIPC. Analysed by Thermo system; CIPC

method in section 2.3.9. 245
Figure 5.9 - Representative chromatograms of 0.1 mg/L CIPC in potato materials
suspension, a) chopped peel, b) blended peel, c) chopped tuber,
d) blended tuber. Analysed by Thermo system; CIPC method in section 2.3.9. 246
Figure 5.10 - Representative chromatograms of 0.1 mg/L CIPC in 78% clarified synthetic
potato wash water. Analysed by Thermo system; CIPC method in section 2.3.9. . 247
19
Figure 5.11 - Degradation of CIPC in River Kelvin water fortified by nutrition at 20°C
(a) and 30°C (b). 252
Figure 5.12 - Oxygen consumption in River Kelvin water fortified by nutrition at 20°C
(a) and 30°C (b). 252
Figure 5.13 - Degradation of CIPC in Glazert Water water fortified by nutrition at 20°C
(a) and 30°C (b). 253
Figure 5.14 - Oxygen consumption in Glazert Water water fortified by nutrition at 20°C
(a) and 30°C (b). 253
Figure 5.15 - Removal of CIPC from potato washing plant effluent and 3CA formation fresh
(a), after 4 months storage at 4°C (b). 256
Figure 5.16 - Zero-, first- and second-order kinetic plots for PWPE from the one day data
of Fig. 5.15a. 256
Figure 5.17 - Removal of CIPC from SPWW and 3CA formation fresh (a), after 4 months
storage at 4°C (b). 260
Figure 5.18 - Zero-, first- and second-order kinetic plot for SPWW from the one day data
of Fig. 5.17a. 260
Figure 5.19 - Degradation of CIPC in solutions containing potato materials. 261
Figure 5.20 - Degradation of CIPC (a) and formation of 3CA (b) in clarified suspensions
obtained after four days of calcium chloride sedimentation. 265
Figure 5.21 - Degradation of CIPC (a) and formation of 3CA (b) in clarified suspensions
obtained after 1 h calcium chloride sedimentation. 268
Figure 5.22 - Degradation of CIPC (a) and formation of 3CA (b) in clarified suspensions
obtained after 1 h sedimentation and fortified with CNP nutrition. 268

Figure 6.1 - Evaporation of CIPC and 3CA standards by two rotary evaporators. 283
Figure 6.2 - Extraction of 10 mg/L CIPC and 3CA from deionised water by four solvents. 284
Figure 6.3 - Representative chromatograms of CIPC in synthetic potato wash water
(SPWW) at different trace levels of a) 0.66 mg/L, b) 0.066 mg/L, c) LOQ
and d) blank. Analysed by Thermo system; CIPC method in section 2.3.9. 290
Figure 6.4 - Representative chromatograms of 3CA in synthetic potato wash water
(SPWW) at different trace levels of a) 0.66 mg/L, b) 0.066 mg/L, c) LOQ
and d) blank. Analysed by Thermo system; 3CA method in section 2.3.8. 291
Figure 6.5 - Representative chromatograms of 0.66 mg/L CIPC in fresh soil extracts
a) Darvel, b) Cottenham and c) Dreghorn 2A. Analysed by Thermo system;
CIPC method in section 2.3.9. 292
Figure 6.6 - Representative chromatograms of 0.66 mg/L 3CA in fresh soil extracts
a) Darvel, b) Cottenham and c) Dreghorn 2A. Analysed by Thermo system;
3CA method in section 2.3.8. 293
Figure 6.7 - Representative chromatograms of 0.66 mg/L CIPC in dried soil extracts a)
Downholland 1A, b) Midelney 1A and c) Quivox B. Analysed by Thermo system; CIPC
method in section 2.3.9. 294
Figure 6.8 - Representative chromatograms of 0.66 mg/L 3CA in dried soil extracts
a) Downholland 1A, b) Midelney 1A and c) Quivox B. Analysed by Thermo
system; 3CA method in section 2.3.8. 295
Figure 6.9 - LLE-VORTEX extraction of CIPC and 3CA from high soil suspension. 297
Figure 6.10 - Microbial degradation of 10 mg/L CIPC and 3CA formation in unfortified
SPWW at 20°C, n = 2. 300
Figure 6.11 - Microbial degradation 10 mg/L 3CA in unfortified SPWW at 20°C, n = 2. 300
20
Figure 6.12 - Microbial degradation of 10 mg/L CIPC and 3CA formation in fortified SPWW
with CNP at 20°C, n = 1. 304
Figure 6.13 - Microbial degradation of 10mg/L 3CA in fortified SPWW with CNP at 20°C,
n = 1. 305

Figure 6.14 - Microbial degradation of 10 mg/L CIPC at different temperatures. 308
Figure 6.15 - Microbial degradation of 10 mg/L 3CA at different temperatures. 309
Figure 6.16 - 3CA Intermediate formation at different temperatures. 311
Figure 6.17 - CIPC linearity and activation energy data. 314
Figure 6.18 - Initial 3CA linearity and activation energy data. 315
Figure 6.19 - Final 3CA linearity and activation energy data. 316
Figure 6.20 - Microbial degradation of 10 mg/L CIPC and 3CA intermediate formation in
three soil suspensions. 319
Figure 6.21 - Microbial degradation of 10 mg/L 3CA in three soil suspensions. 319
Figure 6.22 - Microbial degradation of CIPC and 3CA formation in dried soils. 323

21
Acknowledgement
I would like to express my sincere gratitude and appreciation to my supervisors
Dr. T. H. Flowers and Dr. H. J. Duncan for their combined supervision,
inspiration, support and direction throughout the project.
An acknowledgement is extended to Dr. Geraldine McGowan and the staffs of
Sutton Bridge Experimental Unit for providing the required CIPC-treated
potatoes and the potato wash plant effluents that were used during degradation
experiments.
Special thanks to Dr. John Dolan who is currently a principal instructor for LC
Resources, California and a member of LCGC's editorial advisory board for his
continuous valuable information regarding HPLC analysis and troubleshooting.
I also wish to thank Dr. John Forsythe of 1, 4 Group, USA, for providing
information regarding CIPC application and unpublished potato wash treatments.
I am also grateful to Isabel Freer, Michael Beglan, Stuart Mackay, Ibrahim Madi,
Abdulmohsen Alsukaibi and other precious friends and colleagues at the
Environmental, Agricultural and Analytical Chemistry Section.
The financial support of Taibah University, Madinah, Saudi Arabia, that enabled
this research is highly appreciated.

Finally, and most importantly, I would like to express my sincere gratitude to my
parent, wife and children for their help, patient and support. Without you, it
would have been difficult, if not impossible to carry out this work.


22
Author’s Declaration
I hereby declare that this thesis is my own original research work and effort and
that it has not been submitted anywhere for any award. Where other sources of
information have been used, they have been acknowledged. Some of the results
may have been published elsewhere (Doland & Alsehli 2012).

BANDAR RASHED M. ALSEHLI
February 2014



23
List of Abbreviations
µg
Microgram
3CA
3-Chloroaniline
3CA intermediate
Metabolite produced via CIPC degradation
ACN
Acetonitrile
AU
Absorbance unit
CIPC

Chlorpropham
DAD
Diode array detector
g
Gram
i.d.
Internal diameter
IPC
Propham
LOD
Limit of detection
LOQ
Limit of quantification
M
Mean
m
Metre
MeOH
Methanol
mg
Milligram
min
Minute
24
mL
Millilitre
MPa
Mega Pascal
n
Number of replicate

ND
Not Detected
nm
Nanometre
psi
Pound per square inch
rpm
Revolutions per minute
RSD%
Relative standard deviation (in Percentage)
SD
Standard Deviation
Bandar R. M. Alsehli, 2014 Chapter 1 25
Chapter 1 - Main Introduction
1.1 Background related to the use of sprout
suppressants in the potato industry
1.1.1 Current state of UK potato market
Potatoes make up a significant part of the food market, and it is one of the
feedstock for mass-consumption products, along with rice wheat and maize.
Currently, the demand for potatoes is growing (UK Potato Council 2013c).
According to the data provided by UK Potato Council (2013a), the shares of the
main carbohydrate meal occasions for the four years ending November 2009-
2012 are illustrated in Fig. 1.1.
Figure ‎1.1 - Consumption of carbohydrate meal occasions. Data adapted from UK Potato
Council (2013a).

Bread, potatoes, pasta and rice were consumed in 17.1, 10.1, 2.6 and 1.5 billion
in-home meal occasions, respectively. The in-home potato meal occasions of
10.1 billion meal occasions, which means that each member of the population
consumed almost 3.5 meals a week through different potato meal types. The

types of potato meal occasions are shown in Fig. 1.2.
17.1
10.1
2.6
1.5
0
2
4
6
8
10
12
14
16
18
20
Bread Potatoes Pasta Rice
Meal occasions (billions)
In-home carbohydrate meal occasions
1 year end Nov 2009
1 year end Nov 2010
1 year end Nov 2011
1 year end Nov 2012