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Benefits of converting from helium to hydrogen as a carrier gas for gas chromatography
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Benefits of converting from helium to hydrogen as a carrier gas for gas chromatography


The operational considerations for switching from helium to hydrogen …

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.

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  • 1. Switching from Helium to Hydrogenfor 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 Qatar2
  • 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 years3
  • 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 available4
  • 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/sec5
  • 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)6
  • 7. Increasing the Linear Gas Rate for H2 Raising the rate to 50 cm/sec shortens the separation time to 16 min!7
  • 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 electrolyte8
  • 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 generator9
  • 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 accident10
  • 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.11
  • 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.12
  • 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.13
  • 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 detector14
  • 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 psi15
  • 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 psi16
  • 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 H217