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RT Precursor
Width
Collision Max. Excitation Range
Product Ion
Qualifiers
Compound
(min)
(m/z)
(amu)
Energy (V)
Energy (q)
(m/z)
(m/z)
(m/z)
Dichlorvos
8.48
185
1
3
0.225
53-195
93
131, 109, 170, 63
Molinate
13.05
126
2
3
0.3
45-136
98
83, 55, 82, 81
Trifluralin
13.34
264
2
3
0.225
150-274
206
188, 160, 171, 177
Ethoprophos
14.57
158
2
2
0.225
84-168
114
130, 94, 140
Di-allate
15.45
234
3
3
0.225
140-244
192
150,193
Phorate
15.73
231
2
3
0.225
165-241
203
175, 185
Propyzamide (Pronamide)
16.86
173
2
3
0.225
135-183
145
146
Atrazine
17.42
200
6
4
0.225
84-210
122
132, 94, 134, 158
Diazanon
17.51
179
1
4
0.225
86-189
137
164, 138, 161, 96
Gamma BHC (Lindane)
17.92
219
4
3
0.225
171-229
181
183, 182, 184
Aldrin
22.15
263
1
5
0.225
217-273
229
228, 227, 230, 249
Metribuzin
23.69
198
2
4
0.225
93-208
151
103, 110, 153, 128
Dursban (Chlorpyrifos)
24.16
314
5
3
0.225
248-324
286
258, 287, 288, 285
Malathion
24.16
173
3
4
0.225
125-183
136
145, 137, 138, 135
Sevin (Carbaryl)
24.16
144
1
3
0.3
105-154
116
115
d-10 Parathion
24.34
301
2
3
0.225
105-311
269
147, 115, 148, 271
Parathion
24.49
291
4
3
0.225
99-301
142
263, 137, 109, 114
trans
-Chlordane
25.73
375
4
4
0.225
256-385
301
266, 337, 303, 339
Terbufos
26.02
199
7
3
0.225
133-209
171
172, 153, 143, 173
cis
-Chlordane
26.08
373
5
4
0.225
254-383
301
337, 299, 264, 335
Bifenthrin
28.29
181
7
4
0.225
143-191
166
165, 167, 178, 153
cis
-Permethrin
30.99
183
3
4
0.225
143-193
168
165, 155, 153, 181
trans
-Permethrin
31.19
183
3
4
0.225
143-193
168
165, 155, 153, 181
Table 3: MS/MS parameters for pesticides in tea
Results and Discussion
Linearity
The calibration curve was spiked into the tea matrix.
Levels ranged from 1 ng/g to 1200 ng/g, depending on the
compound and its MRL in green tea. The linearity for most
compounds was R
2
> 0.995. The results of the linearity are
shown in Table 4. Figures 6 and 7 are two examples of
calibration curves.
Limits of Detection and Quantitation
The actual LOD and LOQ were determined by preparing
matrix spikes at a level near or below the MRL.
Concentrations of 7.5, 15, 37.5, 75, or 300 ng/g were
analyzed in seven matrix samples and the LOD and LOQ
calculated from these results by multiplying the standard
deviation by 3.143 and 10 respectively. The results are
shown in Table 5. These results exhibit that this method is
able to meet or exceed the MRL requirements for most of
the compounds, even at the most stringent level.
Method Validation Results
The method validation calculations were performed on
five matrix samples spiked at a concentration of 37.5, 75,
150, 225, 600, or 1200 ng/g. Samples had an average of
104% recovery with an average % RSD of 10.8%. MVD
results for selected concentrations are shown in Table 6.
Conclusions
The ITQ 700 GC-ion trap MS was thoroughly evaluated
and showed excellent accuracy at low concentrations for a
large number of pesticide residues analyzed in green tea.
Using the instrument’s MS
n
functionality allows the user to
identify, confirm, and quantify in one analytical run. The
injector demonstrated low endrin and DDT breakdown
(< 15%) on a daily basis, proving that the system can
analyze active compounds without the need for continual,
expensive, and time-consuming maintenance. Calibration
curves for most pesticides studied met a linear least squares
calibration with a correlation coefficient of R
2
> 0.995.
The Method Validation Study generated an average % RSD
of 10.8% for five replicate analyses at 37.5, 75, 150, 225,
600, or 1200 ng/g and a calculated average LOD of 14 ng/g
in tea based on 7 replicate analyses of 7.5, 15, 37.5, 75,
or 300 ng/g These results demonstrate that the ITQ 700
can comply with international regulations for the control
of pesticides in tea.
