Ongoing helium shortages can cause unpredictability for gas chromatographers. Find the best way for your laboratory to manage price fluctuations and potential delivery interruptions with helium carrier gas for GC analyses.
First, consider whether you really need to use helium as your carrier gas. Regulated methods, SOPs, or high-sensitivity GC/MS methods may require the use of helium. In these cases, helium conservation should be pursued. However, other methods may allow for more flexibility where GC users should consider alternative carrier gases like hydrogen or nitrogen.
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Option 1: Conserve helium
Helium conservation is an easy approach for chromatographers who cannot or do not want to change their GC methods. Try these approaches:
Take advantage of Gas Saver.
Utilize the optional programmable helium conservation module for your Agilent 8890, 8860, or 7890B GC.
Check and maintain your helium infrastructure to prevent leaks.
Agilent Gas Saver works with split/splitless and multimode inlets by reducing the split flow rate at a specified time after the injection while maintaining constant septum purge and column flow rates throughout the GC run. The split flow rate always remains at this lower level except during the injection. Often, the total flow can be reduced by 50% or more by simply using Gas Saver.
The optional helium conservation module should be considered for GC systems that are not running continuously. It automatically switches the carrier gas supply to nitrogen during idle time, keeping the flow path inert and the system at temperature while in standby. This process can be automated with "sleep" and "wake" methods in Agilent OpenLab CDS to prevent interruptions to your GC workflow.
Combining the helium conservation module with Gas Saver can greatly reduce helium consumption when:
Laboratories, especially those with large helium distribution manifolds, should perform a periodic helium use audit and leak check that could reduce consumption and result in substantial savings. Watch this short video to learn how to do this, and see how an Agilent site employed this approach to reduce helium use by 40%.
For a more in-depth look at helium conservation, check out this webinar.
Option 2: Convert to an alternative carrier gas
To avoid any disruptions caused by helium shortages, think about whether an alternative carrier gas would be possible for your analyses. Are you using GC or GC/MS? If GC/MS, consider hydrogen carrier gas. However, if you are doing GC, more options are available. If your method resolution is more than sufficient, try nitrogen. If it is resolution-critical, try hydrogen.
Helium to hydrogen conversion
Methods that will generally require less optimization include analytes that are:
At higher concentrations
Analyzed with split injections
ASTM D5769 - GC/MS analysis of aromatics in gasoline
When converting from helium to hydrogen carrier gas, allow time for necessary updates to SOPs and validation.
There are a few considerations when using hydrogen as a carrier gas.
There are flow limitations with MS pumping capacity, so a turbo pump is recommended.
Peak elution orders and column sample capacity may change slightly.
Hydrogen may interact with analytes and the sample flow path, so an inert column and flow path are recommended. Lower inlet temperatures can reduce the chance of hydrogen reacting with the system.
Certain solvents, such as methylene chloride and carbon disulfide, should be avoided.
Get detailed instructions on converting your Agilent EI GC/MS system from helium to hydrogen carrier gas. While this user guide focuses on GC/MS, it also includes many useful tips for any GC user considering switching to hydrogen carrier gas.
Both GC and GC/MS offer built-in hydrogen safety features. More considerations for GC and GC/MS users working with hydrogen gas are outlined in the Agilent GC/MS Hydrogen Safety user manual.
Helium to nitrogen conversion
Nitrogen often gets a bad reputation as a GC carrier gas due to reduced resolution. But when method resolution is more than adequate with helium, nitrogen can provide a good separation without the supply and cost issues of helium or the safety concerns of hydrogen.
GC analysis of FAME content in biodiesel by EN14103
Method translation for your new carrier gas
Need help converting your existing helium-carrier method to an alternative carrier gas? Check out the method translation software that is built into OpenLab CDS software or can be downloaded as a standalone application. Using your existing helium method parameters, this tool will automatically suggest new pressure, flow, velocity, and temperature program rates for hydrogen or nitrogen, ensuring virtually identical relative retention order.
Learn more about alternative carrier gases from Agilent experts in this webinar.
Comparing carrier gas options
Carefully consider all your options when choosing a carrier gas for your GC or GC/MS method.
Always the first choice, if available
Excellent chromatographic and MS performance
All reference spectra in libraries are obtained with helium
Best alternative to helium
Better chromatographic resolution and speed compared to helium
Widely available in chromatographic grades
Safer than hydrogen
Frequent shortages and delivery interruptions
Inconsistent or high costs
Sometimes difficult to find in chromatographic grades