GC and Helium shortage



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.


1.1         Injector

Mode: splitless

Temperature: 250 oC

Carrier gas: Helium

1.2         Column

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.

1.3         Detector

Type: FID

Temperature: 300oC

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

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