  Most technologies, including conventional mass spectrometry, struggle to
measure the mass of particles in the MDa to GDa range. Although this mass range
appears optimal for nanomechanical resonators, early nanomechanical-MS systems
suffered from prohibitive sample loss, extended analysis time or inadequate
resolution. Here, we report on a novel system architecture combining
nebulization of the analytes from solution, their efficient transfer and
focusing without relying on electromagnetic fields, and the mass measurements
of individual particles using nanomechanical resonator arrays. This system
determined the mass distribution of ~30 MDa polystyrene nanoparticles with a
detection efficiency 6 orders of magnitude higher than previous
nanomechanical-MS systems with ion guides, and successfully performed the
highest molecular mass measurement to date with less than 1 picomole of
bacteriophage T5 105 MDa viral capsids.
