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- Posts: 15
- Joined: Wed Feb 15, 2017 6:29 pm
In order to do this, I'm referencing procedures for impurity calibration from Part 9 of the AHRI standard.
The NOTE after 9.2.3 states, "The purest stock refrigerant will contain some of the impurities found in the method. The ppm amounts of impurities already in the stock refrigerant are determined via the Method of Standard Addition.."
My proposed Standard Addition Method (please critique):
- Vacuum gas bulb and fill gas bulb with high purity Halon 1301 stock as seen in Figure C9-1.
Remove from setup. Set aside. - Setup second gas bulb, evacuate, and fill with known impurities. Then Remove bulb from setup. Set aside.
- Setup third gas bulb, evacuate, and fill with high purity N2. Remove from set up. Set aside.
- Withdraw 0.2mL of high purity Halon 1301 with 1mL gas tight syringe.
- Withdraw (varying amounts: 0.2, 0.4, 0.6 mL) impurities with the same 1mL gas tight syringe.
- Withdraw the balance of the 1mL syringe with high purity N2.
- Inject 1mL sample into GC-MS and run.
Other general information:
- Gas bulbs will be pressurized to 1atm psia.
- Gas tight syringe uses 22-gauge x 1.5" stainless steel deflected point needle.
- The high purity Halon 1301 stock will have been purity tested from an outside lab
QUESTIONS:- Should I avoid mixing and diluting within the syringe? The gas tight syringe has 0.1mL major graduations and 0.02mL sub-minor graduations.
- I plan on using 1mL samples of Halon for future analysis, should I consider different dilution volumes?
- A majority of the impurities are being mixed by a 3rd party vendor with known ppm amounts and the balance N2. A few impurities I will need to introduce, myself. Should I do another standard addition procedure for each impurity I introduce, or will this be dependent on how pure I can purchase that particular component?