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PFMD Stock Level A (400,000 ng/L)
Using a 10 uL cemented needle syringe, add 2.5 .1 µL of neat PFMD reagent into 12.25 mL of Optima Grade hexane in a headspace vial (mixed hexanes will serve equally well).
Serial Dilutions for working standards:
Prepare serial dilutions of stock level A into separate headspace vials. Cap several BLANK vials in advance before working with PFMD to ensure a tracer free background. Use a cemented needle syringe from SGE Corp. (not a plastic-tip pipettor) to add the specified levels (Table 12) of stock solution A to 20 mL crimp-top magnetic cap headspace vials by injecting through the septum. Use the high precision 1 - µL analytical syringe to accurately pipette measure small volumes. Move plunger VERY slowly while drawing and dispensing the solution. You might not be able to see a drop forming at the tip of the needle. Just stay in the vial for a few moments to ensure the entire injection has evaporated into the vial.
The crimp top headspace septa are good for only a few injections; remake standards from the stock solutions solution after five or six injections. Table 2: Calibration standards dilution scheme
Batch | Calibration Level | Reagent STD A added to 20 mL crimp top headspace vial | Concentration (ng/mL headspace) |
Low Level | 4 | 1 µL | 20 |
3 | 0.75 µL | 15 | |
2 | 0.50 µL | 10 | |
1 | 0.25 µL | 5 | |
Blank | 0 µL | 0 | |
High Level | 5 | 62 µL | 1,240 |
4 | 31 µL | 620 | |
3 | 6.2 µL | 124 | |
2 | 0.78 µL | 15.5 | |
1 | 0.25 µL | 5 | |
| Blank | 0 µL | 0 |
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Preparing and Running Calibration Standards
- Use a dedicated LOW STANDARDS syringe for each concentration of tracer. See labels on syringes. this step. Do not use labeled syringes for any other purpose.
- If suspecting contaminated syringes, rinse syringes with methanol (fill syringes with Optima Methanol three times and discard contents, separate plunger and syringe, place segregated on clean foil) and bake them in the oven at 70°C for 12 hours to drive off any possible trace of PFT.
- Prepare dilutions of PFT as per the instructions above.
- In the Agilent Open Lab program, choose Method and Run Control.
- Choose the latest PFT method file and wait until the Ready message is lit. Do not raise the detector temperature without sufficient nitrogen quality and flow!
- If injecting manually, incubate the standards in the 70°C oven for 30 minutes beforehand, as if they were samples. The Gerstel oven should be set to the same temperature.
- Set up a Gerstel autosampler sequence for the calibration standards, or inject each level manually, beginning from the most dilute to the highest concentration. (The samples should be injected by the Gerstel or manually, the same as the standards.)
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