© Benaki Phytopathological Institute
GC multiresidue method of multiclass pesticides
65
20.43% and at the 10*LFL from 88 – 99.7%
with a RSD between 0.55 – 19.14% for most
of the analytes studied. These results also in-
dicate good method accuracy.
Some compounds (aldrin-dichloflu-
anid and pendimethalin-penconazole) co-
eluted in the DB-5-MS column (Table 2). In
case a peak was found at the certain reten-
tion times, an acceptable method of confir-
mation was applied. It is of paramount im-
portance first to confirm the presence of the
compound and then to quantify it. One of
the acceptable confirmation methods is the
use of different polarity columns to confirm
the presence of a compound. According to
Table 5, the proper column for the separa-
tion of the above pairs is the DB-17. Addition-
ally, a GC-MS system can be used. The m/z
Table 4.
Average recovery values and relative standard deviation (RSD) for the 44 analytes in
grapes, as derived from the fortification experiments in both detection systems.
Analyte
LFL
1
(mg/Kg)
Recovery % ± RSD 10*LFL
1
(mg/Kg)
Recovery % ± RSD
acephate
0.02 (MRL)
50.8±4.05
0.2
28.1±7.34
acrinathrin
0.05
109.6±3.66
0.5
97.9±4.16
aldrin
0.01 (MRL)
103.8±1.22
0.1
96.8±5.32
atrazine
0.10 (MRL)
95.2±.1.88
1.0
94.3±1.03
azinphos-methyl
0.10
118.3±2.96
1.0 (MRL)
90.2±0.55
benalaxyl
0.10
105.5±4.79
1.0
96.6±0.81
bifenthrin
0.1
116.8±5.21
1
100.1±3.46
cadusafos
0.05
98.0±2.82
0.5
93.9±1.51
chlorpyrifos-methyl
0.10
100.4±1.77
1.0
97.5±0.87
cyfluthrin
0.05
102.9±2.53
0.5
94.0±3.36
deltamethrin
0.05
96.6±3.57
0.5
88.0±7.35
demeton -S- methyl
0.10
73.4±20.43
1.0
44.4±32.34
diazinon
0.02 (MRL)
100.5±1.83
0.2
97.4±0.76
dichlofluanid
0.1
112.2±1.56
1
90.0±0.94
dichlorvos
0.10 (MRL)
59.5±27.05
1.0
57.5±19.14
dieldrin
0.01 (MRL)
104.2±1.86
0.1
97.1±2.29
dimethoate
0.02 (MRL)
102.2±1.82
0.2
91.4±0.87
endosulfan a
0.05
103.6±0.87
0.5 (MRL)
95.7±2.51
esfenvalerate
0.05
97.3±1.57
0.5
93.1±4.85
ethion
0.10
103.0±2.21
1.0
98.5±1.34
fenpropathrin
0.05
103.6±1.61
0.5
96.1±2.33
fenthion
0.05
95.1±2.39
0.5
89.9±6.93
flucythrinate
0.05 (MRL)
101.9±1.57
0.5
93.1±4.85
fluquinconazole
0.10
120.6±3.97
1.0
76.9±3.84
kresoxim-methyl
0.1
106.2±1.39
1 (MRL)
96.5±2.20
metalaxyl
0.05
117.3±3.93
0.5
97.7±0.27
methidathion
0.02
107.4±7.55
0.2
98.7±2.39
myclobutanil
0.10
120.2±2.00
1.0 (MRL)
92.9±1.02
omethoate
0.10 (MRL)
52.0±6.46
1.0
30.1±5.03
parathion ethyl
0.05 (MRL)
104.3±1.80
0.5
97.2±0.70
parathion-methyl
0.05
98.3±4.02
0.5
89.1±0.87
penconazole
0.05
136.1±1.38
0.5
91.4±2.52
pendimethalin
0.05 (MRL)
102.9±1.41
0.5
95.5±1.86
permethrin
0.05 (MRL)
76.8±4.64
0.5
96.5±2.43
phosalone
0.05 (MRL)
107.2±4.79
0.5
92.4±1.14
prometryn
0.10
101.1±1.60
1.0
96.3±1.40
propiconazole
0.05
171.5±3.66
0.5 (MRL)
93.5±4.38
pyrazophos
0.05
124.6±1.16
0.5
92.9±1.38
simazine
0.10
99.3±1.77
1.0
91.9±1.41
terbuthylazine
0.1
71.5±6.27
1
85.9±9.72
tetraconazole
0.10
116.3±1.41
1.0
95.8±1.07
triadimenol
0.1
117.7±0.89
1
99.7±2.45
triazophos
0.02 (MRL)
106.9±2.13
0.2
96.9±0.86
trifluralin
0.05
95.4±1.60
0.5
93.8±8.34
1
LFL: lowest fortification level; 10*LFL: tenfold fortification level
1...,25,26,27,28,29,30,31,32,33,34 36,37,38,39,40,41,42,43,44,45,...59