GC nitrogen carrier gas solution: Comparing helium and nitrogen in GC-TOFMS exact mass analysis
MSTips No. 317
The global shortage of helium (He), which is used as a GC carrier gas, is becoming a serious issue for various research organizations. As replacement carrier gases such as hydrogen (H2) and nitrogen (N2) are being tried, nitrogen, which is inexpensive and safe, is attracting increased attention. However, nitrogen as a GC carrier gas is known to compromise peak separation and sensitivity of chromatograms as well as qualitative analysis accuracy due to changes in mass spectral data, collectively affecting the analytical results.
In this work, we examined the effects of nitrogen carrier gas on the performance of our GC-TOFMS for high resolution, accurate mass analysis. As a model application, an acrylic resin, which was introduced in MS Tips 300 , was subjected to pyrolysis analysis. EI and FI were used for ionization. Resulting exact mass data was analyzed by msFineAnalysis to derive estimated molecular formulas. The above measurement was performed with helium and nitrogen carriers, and resulting chromatograms and exact mass data were compared to examine the effect of the carrier gases. The EI/FI ion source used for the measurement has an advantage that it does not affect sensitivity when nitrogen is used as a carrier, as discussed in MS Tips 299 . Therefore, it was expected that the analytical results with nitrogen carrier gas would be comparable to those with helium carrier gas.