Two important considerations for selecting a carrier gas are purity and analysis speed. As gas constantly flows into the detector, high-purity gas of at least 99.995 % is needed to reduce baseline noise that could obscure separation analysis results.
For decades helium has been the go-to gas for GC, but recent market instability and looming shortages have many users looking at other options. In particular, hydrogen offers multiple advantages for GC applications, comparing favorably to helium. A VICI DBS gas generator produces high-purity hydrogen and results in faster analysis times.
The Curves Don’t Lie
The van Deemter curve function is useful to compare the carrier efficiencies of different gasses. Band broadening, or separation, is when molecules spread out within a chromatography column, enabling analysis. The van Deemter curve is based on an equation for a hyperbolic function that shows the point where peak separation occurs. The use of different carrier gasses can affect the separation time due to their velocity.
The curve below plots plate height (H) compared to linear velocity of the gasses. Hydrogen can be used at a higher flow rate than either helium or nitrogen—its viscosity increases more slowly with temperature—thus it has higher velocities. A higher linear velocity reduces sample throughput time, increasing the efficiency of laboratory operations.
Using hydrogen as the carrier gas allows efficient separations to be obtained in half the time compared to using helium.
To learn more about using hydrogen generators as a replacement for He cylinders, read the white paper.
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