The operational considerations for switching from helium to hydrogen are explained and options discussed. Analysts need to make decisions about their approach to switching the carrier gas to hydrogen. Are they looking for analysis time reductions or would they like to quickly switch their analysis without having to optimize or change their run conditions? The source of the hydrogen and purity levels needed for its use as a carrier gas are discussed along with the advantages or disadvantages of using hydrogen generators versus gas cylinders.

1. Switching from Helium to Hydrogen
for Gas Chromatography (GC)
In-house generation of Hydrogen leads to shorter analysis times, lower cost
and fewer safety concerns than when Helium is used
March 12, 2013

2. Using Helium in Gas Chromatography
Helium is frequently used as the carrier gas
in GC as it:
• Provides good separations
• Is an inert gas
Helium is a minor component of natural gas.
It is found in Texas, Oklahoma, Kansas
Algeria and Qatar
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3. Issues with using Helium
• It is a critical natural resource
• It is used in a variety of
applications (e.g. cryogenic
cooling, tank purging, welding)
• There is a limited supply which
is being depleted
• The cost has increased
dramatically in recent years
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4. Hydrogen is an Alternative Carrier
Gas for GC
• Hydrogen provides increased column
efficiency (lower HETP), which leads to a
shorter run time
• A lower separation temperature can be
used, which provide for longer column life
and can reduce analyte decomposition
• It is readily available
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5. Comparing the Use of Helium or
Hydrogen
• When H2 is used, a much higher flow rate
can be used…leading to faster
separations.
• He-the optimum flow rate is 20-30 cm/sec
• H2- the optimum flow rate is 25-65 cm/sec
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6. Comparing the Separation at the
Same Linear Gas Rate for Both Gases
Separation of bacterial acid methyl esters is
very similar with He and H2 (flow=25 cm/s)
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7. Increasing the Linear Gas Rate for H2
Raising the rate to 50 cm/sec shortens the
separation time to 16 min!
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8. Generation of Hydrogen
Electrolysis of water
H2O + 2e- → 2 H2 + O2
Via a Metallic Electrode - use 20% NaOH
as an electrolyte
Via a Proton Exchange Membrane (e.g.
Nafion) - does not require an electrolyte
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9. How to Supply H2 to a Gas
Chromatography System
• Use a high pressure H2 tank, which is
available from commercial organizations.
• Use an in-house gas generator
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10. Advantages of In-house Generation
of Hydrogen - Safety
• An in-house generator provides only
the necessary amount of gas that is
ported directly to the GC
• A tank may contain a large quantity of
gas and a leak could cause an
explosion
• Tanks are bulky and transporting
them to the laboratory may lead to an
accident
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11. Advantages of In-house Generation
of Hydrogen - Convenience
• An in-house generator can supply
gas on a 24 h/7d day basis.
• It is not necessary to interrupt
system operation to exchange
tanks.
• It is not necessary to keep extra
tanks in inventory, order new
tanks, etc.
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12. Advantages of In-house Generation
of Hydrogen - Cost
• The operating cost of an in-house generator is
very low. Maintenance involves changing filters
a few times a year.
• If tanks are employed, the overall cost includes
demurrage, the labor cost of changing tanks,
ordering and shipping costs, etc.
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13. Advantages of In-house Generation
of Hydrogen – Green Issues
• In-house generation require only water
and electric power.
• Tank gas requires the transport of heavy
tanks from the supplier’s facility and
empty tanks must be returned to be
refilled.
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14. Switching from Helium to Hydrogen
in the GC Lab
When changing the carrier gas:
• Use High Purity gas - 99.9999% pure
• Adjust the split ratio on the injector
• Adjust the temperature program
• Verify the elution order
• Optimize the detector
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15. Generating Hydrogen with Metal
Electrodes
• The Parker Balston H2PD-300 hydrogen
generator includes Palladium tubes as
electrodes. Only H2 (and its isotopes) pass
through it to provide ultra-high purity gas.
• H2 purity = 99.99999%
• O2 <0.01 ppm, Moisture < 0.01 ppm
• Max. flow rate = 300 mL/min
• Max. Pressure 60 psi
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16. Generating Hydrogen with a Proton
Exchange Membrane
• The Parker Balston H2PEM-510 employs
an ionic polymer (Nafion) to generate H2. A
Pd membrane further purifies the gas.
• H2 purity =99.9995%
• O2 <0.01 ppm, Moisture< 1 ppm
• Max. flow rate = 510 mL/min
• Max. Pressure 100 psi
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17. Benefits of using In-house
Generation of H2 in the GC Lab
An in-house generator provides:
• Faster separations at lower temperature
• Increased safety - tanks are not used
• Increased convenience - 24/7 operation
• Decreased cost - low cost of operation
• Lower energy input than tank He or H2
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