In this post we show how enhanced Cold-EI spectra affect the identification results of NIST library searches.
As shown in Figure 1 below at the third trace the classical EI mass spectrum of n-C20H42 is characterized by a tiny molecular ion with relative abundance of 1.6% while it is the dominant ion in Cold EI as shown in the second trace mass spectrum.
|Figure 2. Combined Isotope Abundance Analysis with the TAMI software and NIST library of n-C20H42. The shown screen is of the TAMI software which fully confirms the NIST identification of the Cold EI MS of n-C20H42. Note the high TAMI software matching factor of 998 and increased combined TAMI-NIST identification probability of 99.97. (Click to Enlarge)|
In summary, Cold EI provides "lower fit but better hit" to NIST library search results.