The Design and Construction of an Ion Trap Based System for Laser Pyrolysis/Mass Spectrometry of Single Organic Aerosol Particles.

Abstract : A multifunction Paul trap capable of stabilizing and analyzing electrostatically charged microparticles as well as a broad range of ions and macro-ions has been developed. Typically, particles in the 0.1-10/m range are introduced by aerosolization and a single particle is selected and stabilized under scattered light observation while the pressure is reduced to < 1(exp-5) torr. A new particle trajectory pattern, observed in the equatorial plane, offers a potentially new, nondestructive, optical method for determining the m/z value of microparticles and macro-ions, with a maximum theoretical accuracy of approx. 1:10(exp 6). Irradiation of the particle with a Nd YAG laser enables production of laser fragmentation/ionization mass spectra of 1 micrometer dia polystyrene particles and of Bacillus subtilis spores. Shot-to-shot reproducibility is still unsatisfactory, however, and mass calibration problems need to be resolved. Nonetheless, the high intensity and complex organic nature of the ion signals indicate the potentiality for chemical and physical characterization of single microorganisms and other components of respirable aerosols. jg