Numbers of
peptides vs type of mass spectrometers employed in Study
1. The number of distinct peptides identified in each experiment bore
a clear relationship to the type of instrument employed. While in
each case instrument vendor libraries performed operations such as
charge state determination and peak picking, the peak lists for identification
may not have been optimal for a variety of reasons. For this informatics
workflow in Study 1 (the upper panel on the left), the Orbitrap and
LTQ-class instruments from Thermo identified a greater diversity of
peptides than did the instruments from other manufacturers. Study
5 results (Sample 1B, the lower panel on the left; Sample 3A, the
upper panel on the right; Sample 3B, the lower panel on the right)
show that the Orbitrap has a larger number of peptides identified
than LTQ. Orbi@86 yielded very high sensitivity for samples 3A and
3B, with OrbiP@65, OrbiW@56, and LTQc@65 trailing behind but still
yielding more diverse peptide collections than the other LTQs.