Journal of Environmental Protection, 2011, 2, 482-488
doi: 10.4236/jep.2011.24056 Published Online June 2011 (http://www.SciRP.org/journal/jep)
Distribution Behaviour of Dimethoate in Tea Leaf
Shivani Jaggi1*, Bikram Singh2, Adarsh Shanker2
1Maya Institute of Technology & Management Selaqui, Dehradun, Uttarakhand, India, 2Institute of Himalayan Bioresource Tech-
nology (IHBT), Council of Scientific & Industrial Research, Palampur (Himachal Pradesh), India
Received February 9th, 2011; revised March 17th, 2011; accepted May 2nd, 2011.
ABSTRACT
A study was undertaken to assess the distribution behaviour of Dimethoate in tea leaf. Tea bushes were subjected to
Dimethoate spray at recommended dose and double the recommended doses. The extraction of pesticide was done using
chloroform and the analysis wa s done using a Hewlett-Packa rd 5890 series II gas chromatog raph with Nitrogen Phos-
phorus Detector (NPD). The penetration behaviour of Dimethoate was studied in dry and wet seasons. Variations in
penetration were observed in dry and wet seasons which was attributed to climatic factors like temperature, humidity,
rainfall, sunlight and physicoch emical properties of the residue like water solubility, partition coeffici ent and formula-
tion type. Residues observed in the cell wall and tissues confirm its good penetrating ability inspite of its hydrophilic
nature. Higher penetration in wet season as indicated can be attributed to the route through the stomatal pores.
Keywords: Tea, Cuticle, Dimethoate, Dissipation
1. Introduction
Tea, Camellia sinensis (L) O. Kurtze, is the most impor-
tant plantation crop in India occupying 420,000 ha of
land. All over the world it is a popular invigorating and
refreshing drink having excellent medicinal properties.
Considering that an estimated amount of 18 - 20 billion
cups are consumed daily in the world its economic and
social interest is clear [1]. Like any other crop tea planta-
tions are also subjected to ravages of insects, mites, plant
pathogens, nematodes etc. The perennial nature of the
crop and the more equitable weather pattern prevailing in
tea areas are favorable for insect pests resulting in
250-500 million kg of annual loss of crop. In terms of
monetary loss it could be approximately 500 million-1
billion US $ [2]. The insects target almost all plant
parts such as roots, stem, leaves and buds. Thus every part
of the tea plant is a potential target for a wide spectrum of
pests and disease causing organisms.
Tea is an unusual crop where leaves are sprayed di-
rectly with pesticides, harvested and processed even
without washing. The shoots of the tea plant are thin and
tender (233 - 291 m) with cuticle thickness 4 - 10 m
and surface area per unit weight of leaf (tender leaf 41.7
cm2/gm and mature leaf 15.9 cm2/gm respectively).Tea
leaf, with thin cuticle, relatively larger surface area and
short interval between pesticide application and harvest,
is expected to be permeable to various groups of chemi-
cals. Pesticide thus could have negative impact both on
ecology and quality of tea when applied [3]. Conse-
quently tea represents a significant potential of human
exposure to pesticide residues by virtue of high applica-
tion of pesticides to tea crop coupled with the average
intake of 6 gms of dried (made) tea per day per individ-
ual [4,5]. Some basic studies on plant cuticles as barriers
against the diffusion of chemicals have been reported
[6,7]. Pesticide penetration into the leaf surface plays
important practical implications as it allows the residues
to stick/persist thus maintaining its efficacy even if it
rains after the treatment [8]. Moreover once the pesticide
has penetrated the epicuticular wax solar radiations act-
ing on the pesticide molecule have to cross the cuticle
thus reducing the photodegradative activity [9]. Further-
more, cuticular wax can hold on the pesticide residues
resulting in low volatility from the leaf surface. The in-
formation available on the fate of pesticides on tea leaf
and role leaf cuticle, plays in the dissipation under dif-
ferent environmental conditions is scanty in literature.
Hence a study was initiated to understand the penetrating
and dissipation behavior of dimethoate on tea leaf sur-
face. Fate of dimethoate in tea and its brew have been
reported but still its exact behaviour on the tea leaf sur-
face is not known thoroughly [10,11].

Distribution Behaviour of Dimethoate in Tea Leaf483
2. Experimental Details
2.1. Field Trials
Field trials were carried out in dry and wet seasons at
Institute of Himalayan Bioresource Technology (IHBT)
tea experimental farm at Banuri, Palampur (1300 msl,
326′20″N × 7633′29″E), India. The maximum and
minimum temperature during dry and wet seasons as
recorded from the experimental farm was 32˚C, 23˚C and
30˚C, 18˚C respectively. Relative humidity was 64% and
82% respectively and the total rainfall was 97 mm during
wet season where as dry season was without any rainfall.
The commercial formulation of dimethoate was sprayed
(spray volume 400 l/ha) on tea bushes considering each
plot of 100 bushes per replicate at recommended dose
(200 gm a.i./ha) and double of the recommended dose
(400 gm a.i./ha). In control treatment (T0), water was
sprayed. Treatments were carried out in dry and wet sea-
sons. Spray was done with a calibrated Knapsack sprayer.
The weather parameters were continuously recorded in
the experimental period to monitor the effect of envi-
ronmental conditions.Green tea leaves (two leaves and a
bud) were plucked from each replicate of both the treat-
ment and control plots and brought to the laboratory each
time at 0 (immediately and 4 hours after spraying),
1,3,5,7,10,14 and 21days after the treatment. To see the
effect of leaky cuticle damaged leaves were also col-
lected from the same plots. Further to analyze the effect
of cuticle on the photodegradation of Dimethoate a labo-
ratory experiment was carried out in parallel by spraying
dimethoate on glass plate (i.e. without leaf) and other
with leaf under same environmental conditions to pro-
vide estimated behavioral information. The weather pa-
rameters during the experimental time are graphically
represented in figure below (see Figure 1).
2.2. Analytical Standards and Working Solutions
An analytical grade of dimethoate was obtained from
Dr.Ehrenstorfer Laboratories, Augsburg, Germany (re-
ported purity > 98%). For the field studies, formulation
grade of dimethoate (Rogor® 30 Emulcifiable Concen-
trate EC, Isagro Agrochemicals Pvt. Ltd., Mumbai) was
procured from the local market. Standard solution (1000
mg/l) was prepared in acetone and the spiking solution
(50mg/l) was diluted from the stock solution and the so-
lutions required for preparing a standard curve (0.2, 0.5,
1.0, 1.5, 5.0 and 10.0 mg/l) were prepared from the stock
solution by serial dilutions. All chemicals used for ex-
traction and analysis of the residues and activated carbon
were products of Merck India Limited, Mumbai India.
Anhydrous sodium sulphate AR (Analytical Reagent)
used was supplied by S.d. fine-chemicals, Mumbai.
Figure 1. Weather parameters.
2.3. Apparatus
Gas Chromatograph
A Hewlett-Packard 5890 series II gas chromatograph
(Avondale, PA-USA) supported by a nitrogen phospho-
rus detector (NPD), a HP-7673 autosampler and integra-
tor (Hewlett-packard) using split-splitless injector, con-
nected to HP 3365 Chemstation system software (Hew-
lett-packard) was used. The detection was done using
Nitrogen Phosphorus Detector (NPD). Peak resolution
was done on a HP-17 medium polar capillary column (25
m length × 0.2 mm id) containing 50% phenyl and 50%
methyl polysiloxane coated fused silica (0.25 µm film
thickness) (Hewlett-Packard, Co., Wilmington, DE). De-
tailed analytical conditions were as follows. The injec-
tion was made using a split mode (50:1), injector tem-
perature held at 260˚C. The temperature of the NPD was
held at 280˚C. The oven temperature was programmed at
150˚C for the initial 2 minutes and then ramped 10˚C
/min to 300˚C and finally maintained for 5 minutes. Car-
rier gas was nitrogen (purity 99.99%) at column flow rate
of 1 ml/min. The samples were filtered through millipore

Distribution Behaviour of Dimethoate in Tea Leaf 484
membrane teflon filters (0.45 µm particle size) before
injection into the chromatographic column.
3. Standard Calibration Curve
Standard curve was prepared by diluting the stock solu-
tion to five different concentrations in acetone. The col-
umn was conditioned by repeated injections (3 times) of
the standard under constant operating conditions until the
peaks obtained were reproducible. Dimethoate was injected
at 0.2, 0.5, 1.0, 5.0 and 10.0 mg/l to validate the method.
Recovery Assay
Before laying the experiments in the field, recovery
studies were performed at 50.0 mg/l fortification level of
active ingredient (three replicates) of each matrix (green
leaves, dried leaves and soil). These samples were pre-
pared by adding known amount of standard in matrix
before extraction. The extraction was carried out as de-
scribed below in section The duplicate injections of each
extract were made in Gas Chromatograph (GC-NPD).
4. Extraction of Pesticide from Leaf Surface
Extraction of dimethoate was done with Chloroform (re-
covery > 90%) The extract was agitated mechanically
with acetonitrile for 3 hours on a horizontal shaker. The
mixture was filtered through Whatman no.1 filter paper
and the cake was washed twice with 20 ml solvent each
time. The combined water extract was partitioned with
150ml of acetonitrile twice in a 500 ml separating funnel.
Discarding the aqueous layer, the organic layer was con-
centrated to near dryness on a water bath and reconsti-
tuted with 1 ml of acetone for final analysis. The effect
of washing was thus confirmed by laboratory washing
and in case of samples collected from the treated fields in
dry and wet seasons, the residue was extracted in dichloro-
methane. The final eluate was evaporated to near dryness and the
residue was reconstituted with 1ml acetone for quantification.
4.1. Extraction of Pesticide from Epicuticular
Wax
Epicuticular wax extraction was done using the method
described by Mc. Donald et al. [12]. After thorough
washing to remove the surface pesticides, the tea leaves
were soaked in 100 ml of chloroform and shaken on an
automatic horizontal shaker for 1 minute. Extract was
filtered through Whatman No.1 filter paper and concen-
trated to 5 ml followed by passing through an adsorbent
column containing florisil topped with 1 cm of anhy-
drous sodium sulphate prewashed with chloroform. The
extract was eluted with 200 ml of chloroform, concen-
trated on a vacuum rotatory evaporator using a water
bath at 35˚C - 40˚C. The residue was finally reconstituted
with 1ml of acetone and quantified by GC (NPD).
4.2. Extraction of Pesticide from Cell Wall
Extraction of dimethoate was done by soaking the tea
leaves in 100 ml of chloroform and shaken on an auto-
matic horizontal shaker for 1 minute. Extract was filtered
through Whatman No.1 filter paper and concentrated to 5
ml followed by passing through an adsorbent column
containing florisil topped with 1 cm of anhydrous sodium
sulphate prewashed with chloroform. The extract was
eluted with 200 ml of chloroform, concentrated on a
vacuum rotatory evaporator using a water bath at 35˚C -
40˚C. The extract was finally eluted with dichloro-
methane (200 ml) from the florisil column. The eluate
was evaporated to dryness and reconstituted to 1 ml in
acetone and 2 µl of it was analysed by GC (NPD).
5. Detection and Quantification
Detection limit test
To determine the limit of detection made tea samples
were spiked with different concentration levels of di-
methoate standard and analysed by GC (NPD). The de-
tection limit was evaluated by the peak signal/noise (S/N)
ratio. An S/N ratio greater than 3 was considered as a
detectable peak.
6. Results and Discussion
6.1. Quantification
The GC analytical conditions were optimized in terms of
temperature program that allowed an improvement of the
time and the chromatographic run resolution. Moreover
to avoid the cross contamination between high and low
spiked samples, the sequence of injections was in the
following order: solvent, blank sample, sprayed samples
and finally standard solution. No interfering peaks were
present during the analysis of any samples as before each
run the solvent was injected.
Moreover, the adopted oven programming allowed a
good chromatographic separation of dimethoate. The total
run time was 14 minutes and the retention time of the
dimethoate in the given chromatographic conditions was
8.68 minutes and constant for each series of samples.
Chromatographic separation by HP-17 column provided
good results for the quantification of the samples.
6.2. Linearity
The calibration curve of the analysed dimethoate gave a
good regression line (R2 = 0.8827) in the range of ex-
plored concentrations, 0.1 - 10.0 mg/l. The detection
limit of dimethoate was taken to be 0.01 mg/kg, which
were much lower than the maximum residue limits fixed
by European Commision for dimethoate in tea (0.2
mg/kg). Residues below 0.01 mg/kg were detected but
not quantified. This low detection limit was achieved

Distribution Behaviour of Dimethoate in Tea Leaf485
because of the efficient cleanup step that allowed the
elimination of all the possible interfering peaks, giving a
low noise value.
6.3. Method Validation
The recovery of the fortified (50 mg/kg) samples of di-
methoate in made tea (in triplicate) ranged from 92.9% -
94.6%. The results showed good recovery and repro-
ducibility. The compounds of interest were well resolved
from other co-extractives. These results indicated that the
method used in this study provided a good cleanup.
6.4. Field Studies
The shoots of the tea plant are thin and tender (233 - 291
m) with cuticle thickness 4 - 10 m and relatively larger
surface area per unit weight of leaf (tender leaf 41.7 and
mature leaf 15.9 cm2/gm respectively). It is an unusual
crop where leaves are sprayed directly with pesticides,
harvested and processed even without washing. In the
preliminary experiments with tea leaf cuticle penetration
of dimethoate was measured immediately after applica-
tion as evaporation of water also affected the rate of
penetration [13].As indicated by data presented in Tables
2-5, the residues of dimethoate on leaf surface at 0 day
(immediately after spray) was found to be 9.07  0.14
mg/kg and 18.31  0.34 mg/kg whereas its concentration
was 9.01  0.10 mg/kg and 18.19  0.34 mg/kg respec-
tively at two different treatments when the samples were
collected 4 hours after spray. No penetration effect ob-
served in the epicuticular wax and cell wall when the
leaves were collected immediately after spray. This indi-
cated that during the evaporation of water the penetration
rate was negligible. In dry season the residue concentra-
tion in the epicuticular wax was 0.14  0.05 and 0.11 
0.10 mg/kg and in the cell wall was 2.97  0.02 and 4.41
 0.08 mg/kg in normal leaf when the samples were col-
lected 4 hours after spray at 200 and 400 gm a.i/ha re-
spectively. While the concentration in injured leaf was
0.17  0.02 and 0.68  0.06 mg/kg in epicuticular wax
and 3.04  0.06 and 6.12  0.12 mg/kg in cell wall.
Further, the concentration in leaf surface was found to
Figure 2. Standard curve.
be 0.02  0.00 mg/kg and 0.04  0.00 mg/kg at two dif-
ferent treatments on 7th day after spray. No residues
were detected on leaf surface after 10th day of treatment.
In wet season, the residue concentration in the cell
wall was 3.24  0.06 mg/kg and 6.25  0.19 mg/kg re-
spectively at two different treatments in normal leaf and
3.32  0.11 mg/kg and 7.20  0.17 mg/kg in injured
leaves whereas in wax the residue concentration was 0.03
 0.00 mg/kg, 0.08  0.01 mg/kg and 0.08  0.00 mg/kg,
0.08  0.00 mg/kg in normal and injured leaves respec-
tively. Further, this concentration in wax was negligible
in normal leaf and injured leaf on 3rd day after spray,
which declined to no detectable limit in 7th day after
spray. As observed from the data, the residues found on
the epicuticular wax and cell wall was comparatively
more in the damaged cuticle.
Residues observed in the cell wall and tissues confirm
its good penetrating ability inspite of its hydrophilic na-
ture. Higher penetration in wet season as observed from
the tables indicated the route could be through the
stomatal pores also. Little variation in the results as ob-
served from Tables 2-5 for normal and damaged cuticle
confirmed that cuticle was also acting as a barrier during
penetration of dimethoate residue. The tea leaf having
thin cuticle is expected to be permeable to various groups
of pesticides and dimethoate residue in the wax and cell
wall confirmed it but cuticle thickness alone may not be
responsible for the dimethoate penetration in the leaf.
Data in Table 1 proved that physical properties of the
Table 1. Physico chemical properties of Dimethoate.
COMMON
NAME DIMETHOATE
CHEMICAL
NAME
O,O-DIMETHYLS-METHYL-CARBAMOYL-
METHYL PHOSPHORODITHIOATE
EMPIRICAL
FORMULA C5H12NO3PS2
MOLECULAR
WEIGHT 229.3
VAPOUR PRES-
SURE 2.5 × 10–4 Pa at 25˚C
PHYSICAL
STATE COLOURLESS CRYSTALLINE SOLID.
MELTING
POINT 45 - 52.5˚C
BOILING
POINT 107˚C at 0.05 mmHg
VOLATILITY 1.107 mg/m3
SOLUBILITY
IN WATER 39 g/l
SOLUBILITY
IN ORGANIC
SOLVENTS
HIGHLY SOLUBLE IN CHLOROFORM,
METHYLENE CHLORIDE, BENZENE,
TOULENE, ALCOHOLS, ESTERS AND KE-
TONES.
SPECIFIC
GRAVITY AT
25˚C
1.281

Distribution Behaviour of Dimethoate in Tea Leaf 486
Table 2. Dimethoate distribution in tea leaf in dry season (200 gm a.i/ha).
Residue in mg/kg  standard deviation
Distribution in normal leaf surface Distribution in injured leaf
D
A
S Leaf surface Wax Cell wall Leaf surface Wax Cell wall
0(1) 9.07 ± 0.14 ND ND 8.96 ± 0.17 0.02 ± 0.00 ND
0(2) 9.01 ± 0.10 0.14 ± 0.05 2.97 ± 0.02 8.65 ± 0.13 0.17 ± 0.02 3.04 ± 0.06
1 6.17 ± 0.15 0.11 ± 0.09 2.03 ± 0.00 5.92 ± 0.12 0.21 ± 0.02 2.79 ± 0.06
3 1.46 ± 0.07 0.02 ± 0.00 0.03 ± 0.00 1.30 ± 0.01 0.02 ± 0.00 0.02 ± 0.00
5 0.05 ± 0.00 ND ND 0.04 ± 0.00 ND ND
7 0.02 ± 0.00 ND ND ND ND ND
10 ND ND ND ND ND ND
14 ND ND ND ND ND ND
21 ND ND ND ND ND ND
Table 3. Dimethoate distribution in tea leaf in dry season (400 gm a.i/ha).
Residue in mg/ kg  standard deviation
Distribution in normal leaf Distribution in injured leaf
D
A
S Leaf surface Wax Cell wall Leaf surface Wax Cell wall
0(1) 18.31 ± 0.34 ND ND 17.60 ± 0.30 0.03 ± 0.00 0.02 ± 0.00
0(2) 18.19 ± 0.31 0.11 ± 0.10 4.41 ± 0.08 17.36 ± 0.25 0.68 ± 0.06 6.12 ± 0.12
1 11.39 ± 0.23 0.90 ± 0.07 4.10 ± 0.10 11.18 ± 0.16 0.33 ± 0.07 5.93 ± 0.06
3 3.13 ± 0.13 0.06 ± 0.00 0.04 ± 0.00 2.95 ± 0.07 0.03 ± 0.00 0.03 ± 0.00
5 0.10 ± 0.01 ND ND 0.06 ± 0.00 ND ND
7 0.04 ± 0.00 ND ND ND ND ND
10 ND ND ND ND ND ND
14 ND ND ND ND ND ND
21 ND ND ND ND ND ND
Table 4. Dimethoate distribution in tea leaf in wet season (200 gm a.i/ha).
Residue in mg/ kg  standard deviation
Distribution in normal leaf surface Distribution in injured leaf
D
A
S Leaf surface Wax Cell wall Leaf surface Wax Cell wall
0 (1) 4.15 ± 0.13 ND ND 3.86 ± 0.10 ND ND
0 (2) 4.00 ± 0.01 0.03 ± 0.00 3.24 ± 0.06 3.65 ± 0.08 0.02 ± 0.10 3.32 ± 0.11
1 0.08 ± 0.00 0.05 ± 0.05 4.14 ± 0.09 0.06 ± 0.00 0.08 ± 0.13 4.25 ± 0.03
3 0.02 ± 0.00 0.02 ± 0.00 0.82 ± 0.03 0.03 ± 0.00 0.01 ± 0.00 0.94 ± 0.02
5 ND 0.03 ± 0.00 0.02 ± 0.00 ND 0.02 ± 0.00 0.02 ± 0.00
7 ND ND ND ND ND ND
10 ND ND ND ND ND ND
14 ND ND ND ND ND ND
21 ND ND ND ND ND ND

Distribution Behaviour of Dimethoate in Tea Leaf487
Table 5. Dimethoate distribution in tea leaf in wet season (400 gm a.i/ha).
Residue in mg/ kg standard deviation
Distribution in normal leaf Distribution in injured leaf
D
A
S
Leaf surface Wax Cell wall Leaf surface Wax Cell wall
0(1) 8.03 ± 0.07 ND ND 7.90 ± 0.05 ND ND
0 (2) 7.83 ± 0.05 0.08 ± 0.01 6.25 ± 0.14 7.44 ± 0.08 0.05 ± 0.00 7.20 ± 0.17
1 0.14 ± 0.02 0.08 ± 0.01 5.24 ± 0.91 0.10 ± 0.01 0.05 ± 0.00 6.64 ± 0.08
3 0.04 ± 0.00 0.05 ± 0.01 1.34 ± 0.09 0.04 ± 0.00 0.04 ± 0.00 1.42 ± 0.07
5 ND 0.05 ± 0.00 0.05 ± 0.00 ND 0.04 ± 0.00 0.03 ± 0.00
7 ND ND ND ND ND ND
10 ND ND ND ND ND ND
14 ND ND ND ND ND ND
21 ND ND ND ND ND ND
residue and environmental conditions might be equally
involved. Low partition coefficient Kow (0.7) and high
water solubility of 39 g/l might have enabled it to pene-
trate inside the inner region of the cuticle. They are rap-
idly absorbed under high humid conditions, supporting
the view that there was an aqueous route traversing the
cuticle and maximum penetration might be due to stomatal
pores. Thus the permeation of active ingredients was
influenced by their solubility characteristics as evident by
their partition coefficients. The Kow reflected the lipo-
philicity of the compound and was related to the degree
and rate at which it would be absorbed by leaf [14]. Fur-
thermore, penetration as observed in the leaf surface could
be attributed to the emulsifiable concentrate formulation
used as they allow better deposits and different adjuvants
keep the deposit in binded form and minimize the early
loss of pesticide by increasing the rate of penetration.
The adhension, retention and distribution of agrochemi-
cals sprayed on plant surfaces also depends on target
wettability [15]. However it could be envisaged that tem-
perature and humidity could have roles to play.
8. Conclusions
Above studies confirmed that the dimethoate distribution
on the tea leaf surface and decrease in surface residue is
due to the collective behaviour of cuticle, its solubility,
penetration, partition coefficient, vapour pressure and the
formulation along with the environmental conditions at
the time of experiments.
9. Acknowledgements
We are especially grateful to Director, IHBT for provid-
ing necessary facilities and CSIR, India for financial as-
sistance. The authors wish to thanks Guru Nanak Dev
University, Amritsar, India for the guidance.
REFERENCES
[1] T. C. Choudhuri, “Pesticide Residues in Tea,” Global
advances in Tea Science , 1999, pp. 369-378.
[2] Anonymous, “Tea,” The Planters Chronicle, Vol. 90, No.
7-9, 1990, p. 319.
[3] N. Muraleedharan, “Pesticide Residues in Tea: Problems
and Perspectives.” The Planters Chronicle, Vol. 9, 1994,
pp. 371-375.
[4] Q. Chen, “Tea—the Best Drinking for Health,” China
Tea, Vol. 3, No. 28, 1985.
[5] Z. Deng, B. Tao and X. Li, “Effect of Tea on the Living
Time of Musca Domesticas and the Anti-Stress of KM
Rats.” Journal of Nanchang University, Vol. 19, No. 2, 1997,
pp. 69-72.
[6] G. S. Hartley and I. J. Graham-Bryce, “Physical Princi-
ples of Pesticide Behaviour,” Vol. 1-2, Academic Press,
London, 1980.
[7] J. Schonherr, and P. Baur, “Cuticle Permeability Studies:
a Model for Estimating Leaching of Plant Metabolites to
Leaf Surface.” Journal of Aerial Plant Surface Microbi-
ology, 1989, pp. 1-23.
[8] P. Cabras, A. Angioni, P. Caboni, V. L. Garau, M. Melis,
F. M. Pirsi and F. Cabitza, “Distribution of Folpet on the
Grape Surface after Treatment,” Journal of Agriculture
and Food Chemistry, Vol. 48, No. 3, 2000, pp. 915-916.
doi:10.1021/jf990069u
[9] P. Cabras, A. Angioni, V. Garau, M. Melis, F. M. Pirsi
and E. V. Minelli, “The Effect of Epicuticular Waxes on
Fruits of Fenthion,” Journal of Agriculture and Food
Chemistry, Vol. 45, No. 9, 1997, pp. 3681-3683.
doi:10.1021/jf970102h

Distribution Behaviour of Dimethoate in Tea Leaf 488
[10] S. Jaggi, C. Sood, V. Kumar, S. D. Ravindranath and A.
Shanker, “Leaching of Pesticide in Tea Brew,” Journal of
Agricultural and Food Chemistry, 2001, Vol. 49, No. 11,
pp. 5479-5483. doi:10.1021/jf010436d
[11] C. Sood, S, Jaggi, V. Kumar, S. D. Ravindranath and A.
Shanker, “Effect of Various Manufacturing Stages on
Pesticide Residues in Tea.” Journal of the Science of
Food and Agriculture. Vol. 84, No. 15, 2004, pp 2123-
2127. doi:10.1002/jsfa.1774
[12] R. E. McDonald, H. E. Nordby and T. G. Mccollum,
“Epicuticular wax morphology and composition related to
grape fruit injury,” Horticulture Science, Vol. 28, 1993,
pp. 311-312.
[13] P. Baur, “Effects on Cuticular Penetration of Neutral Polar
Compounds: Dependence on Humidity and Tempera-
ture,” Journal of Agriculture and Food Chemistry, Vol.
47, No. 2, 1999, pp. 753-761. doi:10.1021/jf980507h
[14] G. G. Briggs, R. H. Bromilow and A. A. Evans, “Relationship
between Lipophilicity and Root uptake and Translocation
of Non-Ionised Chemicals in Barley.” Pesticide Science, Vol.
13, No. 5, 1982, pp. 294-504. doi:10.1002/ps.2780130506
[15] R. E. Gaskin, K. D. Steele and W. A. Forster, “Characterizing Plant
Surfaces for Spray Adhesion and Retention.” New Zealand Plant
Protection, Vol. 58, 2005, pp. 179-183.