High Resolution at Low Mass: Separation of H2 + and D+
Most familiar applications of high resolution mass spectrometry relate to exact mass measurements for elemental composition determination of compounds such as natural products, environmental contaminants, petrochemicals and synthetic organic compounds. However, high resolution can also be useful at the very low end of the mass scale for monitoring gases and isotopes.
The GCmate has a mass range that extends as low as m/z 1 and as high as m/z 3000 (at reduced accelerating voltage) and is capable of a resolving power up to 5,000. This is more than sufficient for analyzing low-mass species such as CO and N2 as well as H+, D+, H2+, HD+ etc. The example shown above was obtained by monitoring H2+ (m/z 2.01565) and D+ (m/z 2.0141) from a mixture of D2O and H2O at a resolving power of 3400. The difference in mass between these two species is only 0.00155 u.