AI10382-GC-MS-Food Safety-Analysis - page 67

7. Standards and Reagent Preparation
7.1 Individual Pesticide Standard Stock Solutions
Prepared gravimetrically in ~1000 mg/L concentration
by weighing 10 mg from each analyte into a 20 mL
amber screw cap vial on a five digit analytical balance
and dissolving in 10 mL of appropriate solvent (acetone,
toluene or acetonitrile depending on the individual
compound). Concentrations of each individual standard
stock solutions were calculated gravimetrically using
weight of added compounds and solvents. All individual
standard stocks were stored in a freezer at -20 °C.
Validity of individual standard stock solutions was
6 months.
7.2 Intermediate Standard Stock and Working
Standard Solutions
Prepared by pipetting the appropriate amount of each
individual standard stock and diluting it with acetoni-
trile. The concentration of intermediate standard stock
solutions was 5000 ng/mL. Working standards were
prepared by diluting intermediate standard stock
solution accordingly. Intermediate standard stock
solutions were stored in a freezer at -20 °C, and the
working solutions in a fridge at 4 °C. Validity of
intermediate stock solutions was 3 months.
7.3 Individual Internal Standard Stock Solutions
Prepared gravimetrically in ~1000 mg/L concentration
by weighing 10 mg from each analyte into a 20 mL
amber screw cap vial on a five digit analytical balance
and dissolving in 10 mL of acetone for TPP and 10 mL
toluene for BFB. Exact concentration values were
determined based on the gravimetrical values of both
weighed compound and added solvent. Individual
internal standard stock solutions were stored in a freezer
at -20 °C. Validity of individual internal standard stock
solutions was 6 months.
7.4 Working Internal Standard Stock Solutions
Prepared individually by pipetting the appropriate
amount of each individual standard stock solution and
diluting it with acetonitrile. The concentration of
working internal standard stock solutions was 5000 ng/mL
and was used for direct spiking of the samples. Validity
of working stock solutions was 3 months.
7.5 1% Sorbitol Solution (Analyte Protectant)
Prepared in 70/30 v/v% ACN/H2O and used for adding
prior to injection. Protectant solution was added to the
sample prior to injection in order to prevent undesired
analyte interaction and consequent losses during the
injection.8
8. Apparatus Part Number
8.1 Fisher precision balance XP-1500FR
8.2 Sartorius analytical balance ME235S
8.3 Thermo Barnstead EASYpure®II water 3125753
8.4 ULTRA-TURRAX® – G25 dispergation tool 1713300
8.5 ULTRA-TURRAX 3565000
8.6 Vortex shaker 3205025
8.7 Vortex universal cap 3205029
8.8 Horizontal shaker 1069-3391
8.9 Horizontal shaker plate 1053-0102
8.10 Thermo Heraeus Freco 17 micro centrifuge 3208590
8.11 Pesticide Analyzer (TSQ 8000 Triple Stage
Qudrupole GC-MS with Thermo Scientific™
TRACE™ 1310)
9. Consumables Part Number
9.1 GC vial kit 60180-599
9.2 Pipette Finnpipette 100–1000 µL 3214535
9.3 Pipette Finnpipette 10–100 µL 3166472
9.4 Pipette Finnpipette 500–5000 µL 3166473
9.5 Pipette holder 3651211
9.6 Pipette tips 0.5–250 µL, 500/box 3270399
9.7 Pipette tips 1–5 mL, 75/box 3270420
9.8 Pipette tips 100–1000 µL, 200/box 3270410
9.9 Spatula, 18/10 steel 3458179
9.10 Spatula, nylon 3047217
9.11 Centrifuge tube rack 1066-3721
9.12 QuEChERS extraction tube, 50 mL, 250 pack 60105-216
9.13 QuEChERS clean-up tube, 15 mL, 50 pack 60105-225
9.14 GC column Thermo Scientific™ TraceGOLD™
TG-5SilMS, 30 m × 0.25 × 0.25 mm 10177894
9.15 PTV Baffle Liner (Siltek), Deactivated,
2 mm ID × 2.75 mm OD × 120 mm Length 453T2120
9.16 2 mL vial rack 12211001
10. Glassware Part Number
10.1 Volumetric flask, 10 mL FB50143
10.2 Volumetric flask, 25 mL FB50147
10.3 40 mL screw cap vial 1054-1593
10.4 Caps for 40 mL screw cap vial 1009-0962
10.5 500 mL bottle 9653640
10.6 100 mL bottle 1006-8060
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