2
Experimental Details
Consumables
Part Number
Columns:
TraceGOLD TG-5SilMS, 30 m x 0.25 mm x 0.25 μm 26096-1420
GuardGOLD 2 m x 0.53 mm ID
26050-0253
Press-Fit
64000-001
Injection port septum:
BTO, 12.7 mm
313032280
Liner:
PTV Silcosteel liner for PTV simulated on-column,
45322052
1 x 2.75 x 120 mm
Column ferrules:
100% graphite ferrules for Thermo Scientific
29053486
TRACE™ injector, 0.53 mm ID
Colum ferrules:
Graphite/Vespel
®
for transfer line, 0.25 mm ID
29033496
Injection syringe:
85 mm 26s Gauge, 10 μL fixed needle syringe
365D0321
for a Thermo Scientific TriPlus™ RSH Autosampler
Sample vials:
Thermo Scientific National™ 9 mm
C4000-11
Target DP Polypropylene Vial, 300 µL
Thermo Scientific National 9 mm Target DP™ Vial,
C4000-9TR
Total Recovery with 10 µL Reservoir
Thermo Scientific Chromacol™ 9 mm screw caps 9-SC(B)-ST101
with High Purity Silicone/PTFE septa
LC-MS grade water
Preparation of Calibration Standards
A stock standard solution of 1 mg/mL of bifenthrin, permethrin, cyfluthrin, and cypermethrin was prepared in ethyl
acetate. Calibration standard solutions were then prepared in ethyl acetate at the following concentrations: 50, 100, 200,
500, 1000, and 2000 ng/mL. A 100 µL aliquot of each calibration standard was then placed into an autosampler vial
followed by the addition of 10 µL of 10 µg/mL of internal standard to each vial.
Sample Preparation: SPE Extraction Protocol
Part Number
SPE cartridge:
Thermo Scientific HyperSep™ C18 SPE column,
60108-701
2000 mg/15 mL
Compound:
(i) Bifenthrin, (ii)
cis/trans
permethrin, (iii) cyfluthrin,
and (iv) cypermethrin 1 L each at 0.10 ng/mL in water
Matrix:
LC/MS water
Conditioning stage:
10 mL ethyl acetate, 10 mL acetone, 2 x 10 mL aliquots water applied
sequentially to the SPE cartridge and then pulled through under
vacuum at 4-5 mL/min
Application stage:
1 L of sample was applied to the SPE cartridge under vacuum
at 4-5 mL/min
Washing stage:
10 mL of water was added to a 1 L vessel, swirled, and placed onto the
SPE cartridge. Then the cartridge was dried for 20 min under vacuum.
Elution stage:
10 mL ethyl acetate was added to the sample vessel, swirled, and then
placed onto the SPE cartridge. Then an additional 10 mL ethyl acetate
was applied directly onto the cartridge.
Additional stages:
Solvent was evaporated to dryness at 40 °C and the residue
reconstituted in 100 µL of ethyl acetate to give the final concentration
of pyrethroids at 1000 ng/mL. Then 10 μL of 10 μg/mL of internal
standard was added to the vial.
