Size-resolved online chemical analysis of nanoaerosol particles: a thermal desorption differential mobility analyzer coupled to a chemical ionization time-of-flight mass spectrometer
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E-Artikel
Titel:
Size-resolved online chemical analysis of nanoaerosol particles: a thermal desorption differential mobility analyzer coupled to a chemical ionization time-of-flight mass spectrometer
Beschreibung:
<jats:p>Abstract. A new method for size-resolved chemical analysis of nucleation
mode aerosol particles (size range from ∼10 to ∼30 nm) is presented. The Thermal Desorption Differential Mobility Analyzer
(TD-DMA) uses an online, discontinuous principle. The particles are charged,
a specific size is selected by differential mobility analysis and they are
collected on a filament by electrostatic precipitation. Subsequently, the
sampled mass is evaporated in a clean carrier gas and analyzed by a chemical
ionization mass spectrometer. Gas-phase measurements are performed with the
same mass spectrometer during the sampling of particles. The characterization
shows reproducible results, with a particle size resolution of 1.19 and the
transmission efficiency for 15 nm particles being slightly above 50 %. The
signal from the evaporation of a test substance can be detected starting from
0.01 ng and shows a linear response in the mass spectrometer. Instrument
operation in the range of pg m−3 is demonstrated by an example
measurement of 15 nm particles produced by nucleation from dimethylamine,
sulfuric acid and water.
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