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- Using a cemented-needle 10 µL syringe, inject neat PFMCH into calibration level 7 (¿).
- Allow the PFMCH aliquot to completely evaporate (~10 minutes).
- Use a gastight syringe to extract 0.5 mL of ¿ 7 through the septum, and inject it into vial 6.
- Continue serial dilutions as noted to create all calibration levels as shown in Table 1.
Calibration Level | Reagent added to 20 mL crimp top headspace vial |
Concentration (ng/mL [ppb]) |
7 | 10 µL PFMCH | 900,000 |
6 | 0.5 mL Level |
7 (900,000 ng/L) | 22,500 |
5 | 0.1 mL Level |
7 (900,000 ng/L) | 4,500 |
4 | 0.5 mL Level |
6 (22,500 ng/L) | 562.5 |
3 | 0.5 mL Level |
5 (4,500 ng/L) | 112.5 |
2 | 0.5 mL Level |
4 (562.5 ng/L) | 14.1 |
1 | 0.5 mL Level |
3 (112.5 ng/L) | 2.81 |
Table 1. Dilution scheme for PFMCH.
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Prepare serial dilutions of stock level A into separate headspace vials. Use a cemented needle syringe from SGE Corp. (not a plastic-tip pipettor) to add the specified levels (Table 1) of stock solution A to 20 mL crimp-top headspace vials by injecting through the septum. Use the high precision 1-µL analytical syringe to accurately pipette small volumes. The crimp top headspace septa are good for only a few injections; remake standards from the stock solutions 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 |
Table 2: Serial dilution scheme for PFMD.
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