Novel mass spectrometry technology development for large organic particle analysis

Abstract

Recently, mass spectrometry has been extended to detect large organic particles and biomolecules, which include large protein polymers, organic polymers, nanoparticles, virions, microparticles and cells. Different novel technologies have been developed to detect these very large particles. In this review, a brief introduction to the technology development is given, and future perspectives on the applications are included. In terms of the detection of very large biomolecules, a macromolecular ion accelerator was developed to achieve sufficient molecular ion energy to reach the megavolt region and increase the detection efficiency. Ions with mass-to-charge ratios (m/z) reaching 30 000 000 were successfully detected. For larger organic or bioparticles, laser-induced acoustic desorption was developed for placing these particles inside a quadrupole ion trap. Measurements of the masses of mammalian and poultry erythrocytes, organic microparticles and cells were achieved by a mass spectrometer with laser-induced acoustic desorption, a frequency-scanning ion trap and charge detection. The mass distributions of these particles were also determined. For nanoparticles and viruses, the number of charges on each particle is too low for accurate determination by a charge detector. The direct detection of nanoparticles/virions by a charge amplification detector is not feasible due to the low velocities of these nanoparticles. A novel approach was developed based on the simultaneous measurement of the different sizes and different numbers of charges of each nanoparticle to derive the masses of the nanoparticles. Due to recent developments in the detection of large organic particles, mass spectrometry can be used to detect masses ranging from atoms to cells.