On‐line laser desorption/ionization mass spectrometry of matrix‐coated aerosols

Abstract

Matrix-assisted laser desorption/ionization (MALDI) was used for the on-line analysis of single particles. An aerosol was generated at atmospheric pressure and particles were introduced into a time-of-flight (TOF) mass spectrometer through a single-stage differentially pumped capillary inlet. Prior to entering the mass spectrometer, a matrix was added to the particles using a heated saturator and condenser. A liquid matrix, 3-nitrobenzyl alcohol (NBA), and a solid matrix, picolinic acid (PA), were used. Particles were ablated with a 351 nm excimer laser and the resulting ions were mass-separated in a two-stage reflectron TOF mass spectrometer. Aerosol particles containing the biomolecules erythromycin and gramicidin S were analyzed with and without the matrix addition step. The addition of NBA to the particles resulted in mass spectra that contained an intact molecular ion mass peak. In contrast, PA-coated particles did not yield molecular ion peaks from matrix-coated particles.

Single Particle Mass Spectrometry–Bioaerosol Analysis by MALDI MS

“…A more powerful approach for on-line bioaerosol analysis is aerosol MALDI mass spectrometr y, as employed by Murray and coworkers. 25,26) Jackson et al 25) reported the on-line MALDI TOF MS analysis of proteinaceous material, whereby the particles were coated in-flight with the matrix nitrobenzyl alcohol.…”

Matrix‐free laser desorption/ionization of ions landed on plasma‐treated metal surfaces

“…33 It is also worth noting that a MALDI study attempting to generate gas-phase complexes of gramicidin S with transition metal cations resulted in protonated ions used as matrix, while metal cation adducts were negligible. 34 In contrast, nontraditional surface matrices such as highly ordered mesoporous WO 3 -TiO 2 showed a clear preference to form [M C K] C adducts.…”

Single-Particle Aerosol Mass Spectrometry (SPAMS) for High-Throughput and Rapid Analysis of Biological Aerosols and Single Cells

“…In aerosol MALDI mass spectrometry, aerosol particles coated with a matrix are either produced from a particle sample suspended in a MALDI matrix solution that is aerosolized or aerosol particles are coated on-the-fly with a vaporized MALDI matrix. Others have explored this approach before obtaining some encouraging results but have also reported challenges in obtaining reproducible mass spectra with aerosol MALDI-MS presumably due to non-uniform matrix coating of aerosol particles (35)(36)(37)(38)(39). Using aerosol MALDI, where peptides were mixed with a MALDI matrix (2,5-Dihydroxybenzoic acid or 2,5 DHB) and aerosolized, we could demonstrate the very high sensitivity of the SPAMS method reaching a 14 zmole detection limit for Gramicidin S, a peptide with molecular mass of 1141 Da (40).…”