© Benaki Phytopathological Institute
Vlastaras
et al.
60
dichloromethane and petroleum ether were
used in the extraction procedure. All sol-
vents were of pesticide residues grade and
were obtained from Lab Scan (Ireland).
(b) Pesticide standards
In this study, 44 analytes were selected
with distinct physicochemical characteris-
tics as shown in Table 1
(2, 7). They included
polar and non-polar compounds, as well as
compounds of various molecular masses.
Representative analytes for various
chemical groups, including organophos-
phorus, organochlorine, triazole, triazine,
strobilurin, pyrethroid, dinitroaniline and ni-
trogen-containing pesticides, were select-
ed according to their physicochemical prop-
erties, such as polarity, water solubility and
vapour pressure (see Introduction). It is im-
perative to add that these are not the only
physicochemical parameters that may used
to select the representative analytes. The
Table 1.
Analytes studied, their chemical class and basic physicochemical characteristics.
Analyte
K
OW
, logP
Vapor Pressure (mPa)
Solubility (mg/l)
Organophosphorous
acephate
-0.89
0.226 (24
o
C)
790 g/l (20
o
C)
azinphos-methyl
2.96
c. 4-5 (20°C)
0.32 (20°C)
cadusafos
3.9
1.2x10
2
(25°C)
248
chlorpyrifos-methyl
4.24
3 (25
o
C)
2.6 (20
o
C)
diazinon
3.30
12 (25
o
C)
60 (20
o
C)
dichlorvos
1.9 (OECD 117); 1.42
(separate study)
2.1x10
3
(25°C) (OECD 104)
c. 18 g/l (25°C)
demeton s-methyl
1.32 (20°C)
40 (20°C)
22 g/l (20°C)
dimethoate
0.704
0.25 (25°C)
23.8 g/l (20°C)
ethion
4.28
0.20 (25°C)
2 ppm (25°C)
fenthion
4.84
0.74 (20°C); 1.4 (25°C)
4.2 (20°C)
methidathion
2.2 (OECD 107)
2.5x10
-1
(20°C)
200 (25°C)
omethoate
-0.74 (20
o
C)
3.3 (20
o
C)
Readily soluble in water
parathion–ethyl
3.83
0.89 (20°C)
11.0
parathion-methyl
3.0
0.2 (20°C); 0.41 (25°C)
55 (20°C)
phosalone
4.01 (20°C)
<0.06 (25°C)
3.05 (25°C)
pyrazophos
3.77 (20°C)
1.6x10
-3
(20°C)
33 (20°C)
triazophos
3.34
0.39 (30°C); 13 (55°C)
39 (pH 7, 20°C)
Amides
dichlofluanid
3.7 (21
o
C)
0.014 (20
o
C)
1.3 (20
o
C)
metalaxyl
1.75 (25°C)
0.75 (25°C)
8.4 g/l (22°C)
benalaxyl
3.54 (20°C)
0.66 (25°C, gas saturation
method)
28.6 (20°C)
Triazoles
fluquinconazole
3.24 (pH 5.6)
6.4x10
-6
(20°C)
1 (pH 6.6, 20°C)
myclobutanil
2.94 (pH 7-8, 25
o
C)
0.213 (25
o
C)
142 (25
o
C)
penconazole
3.72 (pH 5-7, 25
o
C)
0.17 (20
o
C) 0.37 (25
o
C)
73 (25
o
C)
propiconazole
3.72 (pH 6.6, 25°C)
2.7x10
-2
(20
o
C); 5.6x10
-2
(25°C)
100 (20°C)
tetraconazole
3.56 (20°C)
0.18 (gas saturation method)
156 (pH 7, 20°C)
triadimenol
3.11
0.02 (20°C); 0.06 (25°C)
64 (20°C)
Organochlorines
aldrin
6.50
8.6 (20°C)
0.027 (27°C)
dieldrin
5.40
0.4 (20°C)
0.186 (20°C).
endosulfan-a
4.74 (pH 5)
0.83 (20
o
C)
0.32 (22
o
C)
Pyrethroids
acrinathrin
5.6 (a.i. 20
o
C)
4.4x10
-5
(25
o
C)
< or = 0.02 (25
o
C)
bifethrin
>6
0.024 (25
o
C)
<1 μg/l
1...,20,21,22,23,24,25,26,27,28,29 31,32,33,34,35,36,37,38,39,40,...59