(a) Illustration of the single-particle ion trap mass spectrometer. Aerosols enter the inlet orifice and are tightly collimated into a particle beam by the aerodynamic lens system. The particle beam passes through a skimmer into the main chamber of the mass spectrometer. The particles are intercepted by focused diode laser beams apart and their scattered light is detected by two separate PMTs. Their time of flight between the two detection points is recorded for direct correlation to the aerodynamic particle size. Timing electronics trigger a focused pulsed laser to fire when the particle reaches the center of the ion trap. The nascent ions from the particle are then mass analyzed by standard ion trap techniques. (b) Picture of final instrument.
Aerodynamic size distribution of ambient airborne particles.
Positive ion mass spectra acquired from individual airborne particles sampled from laboratory air with aerodynamic sizes of (a) , (b) , and (c) .
(a) Aerosol mass spectrum of acetaminophen particles generated by nebulization from a 50% by volume solution of methanol and water, (b) isolation of parent acetaminophen ion at , (c) MS/MS spectrum of ion with a collision energy of 1.0 and of 0.3, (d) MS/MS/MS spectrum of the fragment and (e) MS/MS/MS/MS spectrum of the fragment.
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