3
Separation Conditions
Part Number
Instrumentation:
Thermo Scientific TRACE GC Ultra
Carrier gas:
Helium
Column flow:
1.0 mL/min, Constant flow
Oven temperature:
90 °C (1 min), 30 °C/min, 180 °C (0.5 min), 5 °C/min, 280 °C (5 min),
30 °C/min, 320 °C (10 min)
Injector type:
Programmable Temperature Vaporizer (PTV)
Injector mode:
PTV Splitless (0.75 min)
Injector conditions:
80 °C (0.05 min), evaporation 14.5 °C/sec, 180 °C (1 min), transfer
2.5 °C/sec, 300 °C (3 min), 14.5 °C/sec, 330 °C (20 min) 50 mL/min
flow rate
MS Conditions
Instrumentation:
Thermo Scientific ISQ Single Quadrupole mass spectrometer
Transfer line temperature:
282 °C
Source temperature:
280 °C
Ionization conditions:
EI
Electron energy:
70 eV
Injection Conditions
Instrumentation:
Thermo Scientific TriPlus Autosampler
Injection Volume:
2 µL
Data Processing
Software:
Software: Thermo Scientific XCalibur
™
Segment
Compound
Start time
(min)
m/z (Quan) Qual ions Dwell time/
sec
1
Dichlobenil
3.50
(171), 173, 100, 136
0.05
2
Tribromoanisol
6.20
(346), 344, 329, 331
0.05
3
Sulfotep
6.80
(322), 97, 202, 146
0.05
4
Hexachlorobenzene
7.40
(284), 282, 283, 214
0.05
5
Parathion
10.40
(291), 109, 97
0.05
6
Triphenylphosphine (IS)
13.00
(262), 183, 108
0.05
7
EPN
18.90
(157), 169, 141, 110
0.05
8
Azinphos methyl
19.00
(160), 77, 132
0.05
9
Permethrin
20.90
(183), 163, 165, 153
0.05
10
Fenvalerate
23.00
(125), 167, 225
0.05
11
Deltamethrin
25.60
(253), 181, 251, 152
0.05
Results
In order to assess the method linearity, a calibration curve
was constructed for each of the ten pesticides spiked in
the sample matrix, using triphenylphosphine as the
internal standard (IS). The concentration range studied for
the selected pesticides in Table 2 was 25 to 1000 ng/g. The
coefficient of determination (R
2
) between area ratio of
sample and internal standard for all pesticides were higher
than 0.99 (Table 2), demonstrating good method linearity.
The analysis was performed in SIM. Figure 2 shows the
TIC chromatogram of spiked pesticides in cucumber
matrix at 10 µg/g in full scan. Six extractions of ten
pesticides in sample matrix spiked at 50 ng/g were
measured. These values do not appear to correlate with
those in table 2.
The recoveries for spiked pesticides
were between 75 and 120%, with an relative standard
deviation (RSD) under 9% (Table 2).
Table 1: SIM Scan Parameters
