Dr. Bruce Quimby is a Senior Applications Scientist in the Mass Spectrometry Division of Agilent Technologies, located in Wilmington, Delaware. He is currently working on GC/MS applications in multiple areas including environmental and food safety.
Lakshmi Krishnan is the GCMS Single Quadrupole Product Manager in the Mass Spectrometry division of Agilent Technologies, located in Santa Clara, California. Lakshmi obtained her M.S. in Biotechnology with a focus on Business Administration, from San Jose State University. At Agilent, she works on new product introductions, marketing, and commercialization of GC/MSD platforms.
Q: How has the recent helium (He) shortage affected GC/MS labs?
A: In the past, He shortages have led to higher He gas prices and delayed deliveries, but this is the first time we are seeing a complete lack of delivery due to restricted supply.
Q: Under the current scenario of price fluctuations with He and potential delivery interruptions, what steps must be taken?
A: The first step would be to consider whether your lab requires He or not. For SOPs or regulated methods that call for He, He conservation techniques would be an easy alternative for those who do not want to change their GC methods. Technologies such as ‘Gas Saver’ and the ‘Helium Conservation Module’ assist with this. Another important step labs should follow is to check and maintain their helium infrastructure to prevent leaks.
When considering alternate carrier gases due to interruptions in helium supply, nitrogen (N2) is not recommended due to limitations in performance, particularly sensitivity. Hydrogen (H2) is the best alternative for GC/MS analyses, providing greater chromatographic resolution, speed, and a diverse range of applications while also offering the fewest limitations when compared to N2.
Q: One of the concerns about H2 is safety due to its flammability. How are these concerns addressed?
A: Safety is always the first and most important consideration when handling gases. Agilent has a long history of over 50 years in manufacturing GCs and GC/MSs with extensive experience in design and testing for safety with H2 gas. Our products have been engineered for use with hydrogen for over 40 years, and we are confident of the safety protocols we have in place with our instruments. Our GCs are built with H2 safety features like safety shutdown protocols, flow limiting frits, and oven On/Off commands to program into your sequences. For detailed safety information, see the Agilent Hydrogen Safety Manual for GC/MS (part number G7003-90053). H2 generators can also be used, as they also offer some useful safety features.
Q: If a lab decides to switch from He to H2 gas, what are the requirements that must be considered?
A: A lab must consider the following changes in a move from helium to hydrogen gas:
- GC/MSD and GC/TQ hardware changes—like switching to a 9 mm drawout lens, and if possible, using the HydroInert source that has been designed for use with H2 carrier gas
- Choosing new chromatographic conditions, including selecting a column and method conditions appropriate for H2 flow rates
- Potential reduction in signal-to-noise (S/N) ratio (2 to 5 times or more) due to higher noise
- Changes in spectra and abundance ratios for some compounds
- Activity and reactivity of H2 with some analytes—consider using a multimode inlet (MMI) in the cold splitless mode for compounds susceptible to reactions
Agilent has a very helpful document detailing the steps for conversion: Agilent EI GC/MS Instrument Helium to Hydrogen Carrier Gas Conversion User Guide (part number 5994-2312EN). If additional assistance is desired, Agilent CrossLab application and method migration consulting service can guide you to overcome application problems and help you optimize your H2 methods.
Q: Agilent GC/MSs have historically been able to run on H2 carrier gas, so what is the need for this new HydroInert technology?
A: HydroInert is a new EI source that is optimized for use with hydrogen. There are design improvements that help significantly improve spectral and chromatographic performance. In other words, previously a system could run on H2 and have some limitations in data, but now we see a substantial improvement with the use of HydroInert.
It opens the door for a wide variety of applications that can now run with H2 that were previously restricted to He. For example, with single quadrupole instruments used to identify unknowns, the improved spectral fidelity of HydroInert makes H2 use much more practical. With triple quadrupole instruments used for pesticides in food, HydroInert improves low-level detection, permitting most analytes to be measured down to 1 ppb.
Q: What are the key takeaways for the readers from this discussion?
A: If you can still reliably get He and the price is not a major concern, it is still the recommended carrier gas to use. We’ve discussed ways to overcome the He shortage. One of them is saving He, and the second is an alternative carrier gas, most notably H2. Current He methods can be converted to H2 carrier gas—and we have numerous ways, like calculators and guides, to help do that—but keep in mind there will be reduced S/N (sensitivity) with H2. Our recommendation is to include HydroInert when considering switching to H2 carrier gas to avoid reactivity issues and help get the best out of your spectra.