Abstract Number: 279 Working Group: Instrumentation and Methods
Abstract A particle trap laser desorption mass spectrometer (PT-LDMS) has been developed for online particle measurements of sulfate, nitrate, and organic carbon. The first prototype of the PT-LDMS, as given by Takegawa et al. (Aerosol Sci. Tech., 2012), has been used in the laboratory to demonstrate the proof of concept. Here we present the second prototype, which is aimed to be a compact, field deployable instrument (total size of 800 mm (W) x 700 mm (D) x 800 mm (H) with two 300 l/s turbo molecular pumps (TMPs), one 80 l/s TMP, and 90 l/min backup scroll pump.)
Aerosol particles collected on the particle trap are vaporized by the CO2 laser. The evolved gas is confined within a cell and introduced into the QMS. The quartz cell used in the first prototype has been replaced with a gold-coated aluminum one for easier machining and maintenance. The measurement cycle, which consists of particle collection, inlet valve closing, laser desorption, and data acquisition, can be fully automated. The nominal collection time of 7 min and analysis and buffer time of 3 min yields the time resolution of 10 min. Evaluation of the instrument performance during ambient measurements and intercomparison with other instruments will be discussed in the presentation.