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- Pipette 12.25 ml of Optima grade Hexanes (that is what we currently use as of X395C) into a 20 mL headspace vial.
- Cap the vial with a PTFE septum (cream-colored "shiny" side facing the vial) and a magnetic crimp cap.
- Using a 10 uL µL cemented needle syringe, add 2.5 µL of neat PFMD into the vial. Let the needle remain the vial for a few moments after the injection to ensure all PFMD from the needle tip has evaporated into the vial.
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Table 2: Serial dilution scheme for PFMD. As of Exp395C, we are only using the Low Level calibration.
PFD calibration Level | µL STD A added to 20 mL screw cap GC2 vial | Concentration PFD (ng/mL headspace) |
BLANK | 0 | 0 |
1 | 0.02 | 0.1 |
2 | 0.04 | 0.2 |
3 | 0.06 | 0.3 |
4 | 0.1 | 0.5 |
5 | 0.2 | 1 |
6 | 1 | 5 |
7 | 2 | 10 |
8 | 4 | 20 |
Table 3: Dilution scheme for PFD.
To prepare STD A with PFD, pipet 13.72 mL hexane into a GC2 vial, cap the vial, add 0.7 µL PFD through the septum. The dilution follows the traditional PFMD dilution scheme. Concentration of STD A has been adjusted to allow for accurate syringing of extremely low volumes.
Hardware
The GC2 system comprises an HP 6890 gas chromatograph (GC) with a micro-electron capture detector (µECD).
The GC inlet is operated in splitless mode. PFT gas samples obtained using the headspace extraction method may be injected manually after incubation for 30 minutes at 70 deg. C, or can be injected by the Gerstel autosampler (whose incubator oven should be set to 70°C for 600 seconds). The injection port liner assembly is connected to a megabore column (Rt-Alumina BOND/KCl, 50 m, 0.53 mm ID, 10 µm thickness), and then to a µECD detector, which requires both carrier (helium) and makeup gases (nitrogen).
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