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GCxGC-TOFMS Chromatogram of QuEChERS Extract of Lemon Using Rxi-5Sil MS and Rtx-200

GC_FF1218
ColumnRxi-5Sil MS 30 m, 0.25 mm ID, 0.25 µm (cat.# 13623)
Rtx-200 1.5 m, 0.18 mm ID, 0.20 µm (cat.# 45001)
SamplePesticides in lemon extract
QuEChERS internal standard mix for GC-MS analysis (cat.# 33267)
Diluent:Acetonitrile
Injection
Inj. Vol.:1 µL splitless (hold 1 min)
Liner:Gooseneck splitless (5 mm) w/deactivated wool (cat.# 22973-200.1)
Inj. Temp.:250 °C
Purge Flow:40 mL/min
Oven
Oven Temp.:Rxi-5Sil MS: 90 °C (hold 1 min) to 310 °C at 4 °C/min (hold 2 min)
Rtx-200: 100 °C (hold 1 min) to 320 °C at 4 °C/min (hold 2 min)
Carrier GasHe, corrected constant flow (1.8 mL/min)
Modulation
Modulator Temp. Offset:25 °C
Second Dimension Separation Time:4 sec
Hot Pulse Time:1.2 sec
Cool Time between Stages:0.8 sec
DetectorTOFMS
Transfer Line Temp.:290 °C
Analyzer Type:TOF
Source Temp.:225 °C
Electron Energy:70 eV
Mass Defect:-20 mu/100 u
Solvent Delay Time:5 min
Tune Type:PFTBA
Ionization Mode:EI
Acquisition Range:45-550 amu
Spectral Acquisition Rate:100 spectra/sec
InstrumentLECO Pegasus 4D GCxGC-TOFMS
NotesRtx-200 (cat.# 45001) is a 10 m column. A 1.5 m section was cut off and used as the second dimension column.

Internal Standard: 100 µL of QuEChERS internal standard mix for GC-MS analysis (cat.# 33267) and 100 µL of QuEChERS internal standard mix for LC-MS/MS analysis (cat.# 33261) were added to each 10 g sample. These internal standard mixes require no dilutions (“snap-and-shoot”) and contain compounds specified in the EN 15662 QuEChERS method.

Extraction: 10 mL acetonitrile was added to a 10 gram sample of homogenized lemon. After a 1 minute shake, Q-sep European method extraction salts (cat.# 26236) were added and the sample was pH adjusted with NaOH followed by another 1 minute shake. The sample was then centrifuged with Q-sep 3000 centrifuge (cat.# 26230).

dSPE: Add 1 mL extract to QuEChERS dSPE cleanup tube containing 150 mg MgSO4, 25 mg PSA, and 25 mg C18 (cat.# 26216). Shake for 30 seconds and centrifuge with Q-sep 3000 centrifuge (cat.# 26230).