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MATRIX-ASSISTED LASER DESORPTION IONIZATION OF SIZE AND COMPOSITION SELECTED AEROSOL PARTICLES. (R823980)
Citation:
Monsoori, B. A., A. S. Wexler, AND M. V. Johnston. MATRIX-ASSISTED LASER DESORPTION IONIZATION OF SIZE AND COMPOSITION SELECTED AEROSOL PARTICLES. (R823980). Analytical Chemistry. American Chemical Society, Washington, DC, 68:3595-3601, (1996).
Description:
Matrix-assisted laser desorption/ionization (MALDI) was performed on individual,
size-selected aerosol particles in the 2-8 mu m diameter range, Monodisperse aerosol droplets
containing matrix, analyte, and solvent were generated and entrained in a dry stream of air, The dried
particles were drawn from atmospheric pressure directly into the source region of a reflecting held
time-of-flight mass spectrometer. Individual particles were then detected by light scattering and
analyzed on-the-ny by MALDI, The particle size and composition were systematically varied, and
both liquid and solid matrices were studied, As the analyte-to-matrix mole ratio increased, the
analytesignal intensity first increased and then levelled off. Quenching effects were observed when
two different peptides were present in the same particle, These dependences were interpreted on the
basis of analyte surface activity and adsorption isotherms. With a liquid matrix, the analyte is thought
to partition between the particle surface and bulk, The signal intensity increases with analyte surface
coverage until a monolayer is formed, With a solid matrix, the analyte is thought to adsorb on the
surface of the originaldroplet containing matrix, analyte, and solvent When the solvent evaporates, the
analyte deposits on the dry particle surface. Again, the signal intensity increases with analyte surface
coverage until a monolayer is formed. With either a solid or liquid matrix, signal quenching is
observed when multiple analytes compete for surface adsorption. (33 References)