Single Particle Mass Spectrometry–Bioaerosol Analysis by MALDI MS

Abstract

The development of an aerosol mass spectrometer for the analysis of biological aerosols is described. The working principles of the aerosol mass spectrometer are particle sizing, particle selection and particle analysis by matrix-assisted laser desorption/ionization mass spectrometry (MALDI). The instrument has the capability of selecting only those aerosol particles that emit fluorescence when excited with 266 nm laser light, which differentiates the biological particles from virtually all other particles likely to be present in an aerosol.The implementation of a new ion source and delayed extraction has resulted in the capability of obtaining high-quality mass spectra of single bioaerosol particles. Isotopic resolution was obtained for a low-mass peptide. The sensitivity limit of the instrument was determined to be 1 zeptomole. The suitability of the aerosol mass spectrometer for the analysis of bacterial aerosol particles is demonstrated with an aerosol containing vegetative cells of the bacterium Escherichia coli when prepared off-line. The mass spectrum obtained has good resolution and covers a mass range up to 15 kDalton.