Gas chromatography (GC) uses a wide range of gases including helium, hydrogen, and nitrogen as the carrier gas. The most common carrier gas is helium. In recent years, however, the availability of helium has decreased and its cost has increased significantly. As a result, many chromatographers are now switching to hydrogen as a GC carrier gas.
The availability of helium
Helium is a minor component of natural gas formed by the natural breakdown of uranium. Fractional distillation of natural gas allows for the purification of helium from the natural gas. Many users worry about the future availability of this non-renewable natural resource.
Benefits of hydrogen over helium
Hydrogen offers several advantages over helium as a carrier gas including:
- Increased speed: Increasing the linear flow rate allows for shorter run times, thereby increasing the throughput of a laboratory.
- Achieve lower temperature separations: At the faster elution times, it may not be necessary to increase the column temperature run rate. It is possible to lower the maximum temperature needed for the analysis or remain at those temperatures for shorter periods.
- Longer column life: Lower temperatures lead to less column bleed resulting in longer column life. Hydrogen is a reducing gas and can remove potential acidic sites inside of the column. The removal of these sites leads to less sample absorption and less generation of phase breakdown (column bleed). The result is a longer usable life for the column.
- Environmental concerns: Helium is a by-product of natural gas or petroleum production and there are environmental concerns with the production and purification of the gas. Hydrogen is a green gas in that its production does not contribute to environmental pollution.
- Cost savings: The cost of hydrogen is significantly lower than that of helium.
- Availability: Since hydrogen is generated from the electrolysis of water, there is no need to worry about availability
Sources of hydrogen
Hydrogen can be obtained in the form of cylinders or from an on-site hydrogen generator.
Advantages of a hydrogen generator
- Safety: Eliminates the dangers of handling and storing high pressure hydrogen cylinders. A Parker hydrogen generator contains only 50 ml of stored gas, so there is no large volume of gas that could potentially vent and cause an explosion or asphyxiation. In fact, all Parker hydrogen generators are equipped with automatic shutdown on leak detection, and meet NFPA requirements and OSHA 1910.103 regulations governing the storage of hydrogen.
- Convenience: A hydrogen generator will produce a continuous supply of high purity hydrogen, eliminating the need to interrupt important analysis to change cylinders. There is no need to rely on outside vendors. Concerns over uncontrollable price increases, contract negotiations, long-term commitments, and tank rentals are eliminated.
- Space-saving design: A hydrogen generator frees-up valuable laboratory floor space. The compact design only takes up one square foot of bench space.
- Consistent purity: High purity hydrogen is required for carrier gas applications. Contaminant levels can vary from cylinder to cylinder which can affect sensitive analyses. A hydrogen generator will produce a consistent supply of high purity hydrogen on demand. Also, cylinders are often located a distance from the instrument - requiring long gas lines. Gas lines must be checked regularly for leaks. Leaks allow gas to escape and impurities to enter the gas supply which reduces purity and affects the accuracy of analysis. A hydrogen generator, on the other hand, can be placed next to the instrument it is servicing.
- Cost savings: When compared to the total costs associated with cylinders, a Parker hydrogen generator will pay for itself in one or two years.
This post was contributed by Judy Silva, Gas Generation Technology Blog Team Member - Parker Hannifin