Easing the Switch to Hydrogen as a Carrier Gas on GC-MS
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Helium, having a finite resource and inefficient production process, is very expensive. As such, demand has increased for applications that use hydrogen as the carrier gas.
Despite hydrogen being used successfully in many labs, concerns persist about converting existing helium-based methods to hydrogen. These concerns typically include the length and cost of the switching process, failing to meet the performance of current methods and safety concerns.
To help scientists overcome these issues and make a wider range of applications possible, Agilent recently launched the HydroInert source for hydrogen carrier gas on gas chromatography/mass spectrometry (GC/MS). To learn more about this new introduction and how it is designed to improve chromatographic efficiencies with hydrogen carrier gas we spoke to Aaron Boice, GC/MS marketing manager at Agilent.
Ash Board (AB): What are some of the issues faced when switching from helium to hydrogen as a carrier gas?
Aaron Boice (ABO): Initially switching to hydrogen requires some thought and conversion of existing methods. Agilent has built-in tools in their software as well as a user guide to help customers to migrate from one carrier gas or column format to another. Since hydrogen is a reactive gas, unwanted in-source chemistry such as hydrogenation and dechlorination reactions can occur in the mass spectrometer electron ionization (EI) source. This alongside the commonly increased background signal seen when switching to hydrogen, can impact performance, sometimes quite significantly, making applying hydrogen carrier gas to many applications difficult.
AB: How does the HydroInert source overcome these issues?
ABO: HydroInert minimizes unwanted in-source reactions, preserving spectral fidelity for confident library matches, and allows consistent use of multiple reaction monitoring (MRM) transitions that were developed using helium.
AB: How does the performance compare, are there any drawbacks with switching from helium to hydrogen?
ABO: Helium is still the preferred carrier gas for GC/MS, offering the most inert and sensitive overall performance. Nitrogen has historically been considered due to inertness but suffers in resolution, especially at faster speeds. Now with HydroInert, we find hydrogen is the best alternative when helium is unavailable. Every analyte is different, but we see that spectral fidelity when using hydrogen carrier with the HydroInert source is comparable to traditional EI. Sensitivity when using hydrogen isn’t quite the same as helium, but due to the properties of hydrogen, we appreciate improved chromatographic resolution, especially with high flow rates. This helps with quantitation, and can be leveraged for shorter run times.
AB: Can you explain how the HydroInert source is optimized for use with hydrogen?
ABO: The proprietary materials used in the HydroInert source are key to the optimization. Traditional EI sources create conditions which can catalyze reactions occurring with hydrogen present, however the HydroInert source is more inert to H2, and the mass spectra retain their normal characteristics observed in He mass spectra.
AB: Is the HydroInert source suitable for all applications/samples that currently use helium or are there limitations? Is it possible for labs to overcome these limitations?
ABO: The product is designed to help make a wider range of applications possible, and there are many GC/MS applications we are continuing to test at Agilent and with partners. So far, we have seen excellent results with semi volatile organic compounds (SVOCs), volatile organic compounds (VOCs), and polycyclic aromatic hydrocarbons (PAHs). We will continue to publish our results in other areas as they are available.
AB: Is the HydroInert source available on all Agilent GC/MS and GC/MS/MS systems, can it be retrofitted to existing systems?
ABO: The HydroInert source is available on the 5977A, 5977B, and new 5977C GC/MSD systems. On GC/TQ, it is compatible with the 7000C, 7000D, and new 7000E systems.
Aaron Boice was speaking to Dr. Ash Board, Editorial Director at Technology Networks.