1 research outputs found
Droplet Assisted Inlet Ionization for Online Analysis of Airborne Nanoparticles
Airborne nanoparticles play a key
role in climate effects as well as impacting human health. Their small
mass and complex chemical composition represent significant challenges
for analysis. This work introduces a new ionization method, droplet
assisted inlet ionization (DAII), where aqueous droplets are produced
from airborne nanoparticles. When these droplets enter the mass spectrometer
through a heated inlet, rapid vaporization leads to the formation
of molecular ions. The method is demonstrated with test aerosols consisting
of polypropylene glycol (PPG), angiotensin II, bovine serum albumin,
and the “thermometer” compound <i>p</i>-methoxybenzylpyridinium
chloride. High-quality spectra were obtained from PPG particles down
to 13 nm in diameter and sampled masses in the low pictogram range.
These correspond to aerosol number and mass concentrations smaller
than 1000 particles/cm<sup>3</sup> and 100 ng/m<sup>3</sup>, respectively,
and a time resolution on the order of seconds. Fragmentation of the
thermometer ion using DAII was inlet temperature dependent and similar
in magnitude to that observed with a conventional ESI source on the
same instrument. DAII should be applicable to other types of aerosols
including workplace aerosols and those produced for drug delivery
by inhalation