Fig. 1: Mass resolution and signal-to-noise in Orbitrap-based CDMS scale with the transient recording time.
a, Ion signals of individual ions for HBV at increasing transient times of 128, 256, 512, 1,024, 2,048 and 4,096 ms (left to right), with a mass resolution for the 4 MDa particles extending from ~3,000 at 128 ms to above 100,000 at 4,096 ms (1 Th = 1 Da e–1). Δ means the full-width at half-height of the peak. Ø means the diameter of the virus particle. b, As in a, signals of individual ions of the 9.4 MDa FHV particles, with R approaching 100,000 at 4,096 ms. c, Average number of collisions the ions experience with background gas (xenon) during the transient time (top), with the green dots showing data for HBV and the purple dots for FHV. Although the number of collisions increases linearly, nearly all high-mass ions seem to survive, as evidenced by the observed resolution and signal-to-noise ratio (bottom) that scale exactly as expected with transient time, reaching a value of ~400 for the 9.4 MDa FHV particles at 4,096 ms. Therefore, for high-mass ions (molecular weight > 1 MDa), even longer transient times would lead to even higher resolution and signal-to-noise levels.
