we are currently unable to get Helium. We'll run our Helium gas inventory in a few weeks. Between other applications for our facility, it is used as a carrier gas on our GCs for solvent analysis (validated method). I'm copying our method below. Would it be best to use N2 or H2? How do I calculate the equivalent flow. Any other option?
Thanks in advance.
Temperature: 250 oC
Carrier gas: Helium
Type: fused silica capillary
Model: DB-200 (J&W p/n 122-2033),
Nominal Length: 30m
Nominal diameter: 0.25mm
Nominal film thickness: 0.5 µm
Mode: constant pressure, 15 psi.
Nominal initial flow: 1.4 mL/min.
Hydrogen flow: 40 mL/min
Air flow: 350 mL/min
Mode: constant makeup flow
Makeup gas: Nitrogen (30 mL/min)
1.4 Temperature profile
Initial temperature: 40oC for 2 minutes
Ramp: increased from 40oC to 130oC at a rate of 20oC/min
Ramp time: 4.5 minutes
Post temperature: maintained at 130oC for 5.5 minutes.
Total run time: 12 minutes