Rapid In-Situ Detection of Aerosolized Chemicals of Interest by Single Particle Mass Spectrometry

SCHUYLER LOCKWOOD, Alla Zelenyuk, Pacific Northwest National Laboratory

     Abstract Number: 499
     Working Group: Instrumentation and Methods

Abstract
The PNNL single particle mass spectrometer, miniSPLAT, is currently employed as a “ground truth” instrument for detection of chemical species in aerosols as part of the testing and evaluation efforts for IARPA’s PICARD program. The goal of the program is to develop fieldable sensors that can detect and rapidly identify aerosol particles of interest in challenging environments. In this work, miniSPLAT was used to acquire single particle mass spectra of laboratory generated aerosols that represent model systems for different target materials, including chemical warfare agents, pharmaceutical based agents, such as fentanyl analogs, toxic industrial materials, environmental pollutants, explosives, and radioactive materials.

In most cases, target materials were introduced in the presence of background aerosol particles or “clutter”, resulting in the rapid increase in particle number concentrations above the background level, along with the appearance of particles with different shapes, sizes, and mass spectra compared to those of the background aerosol.

Custom single particle analysis software was used to classify particles with different mass spectra into different classes, making it possible to detect and identify particles composed of the target material within a couple of minutes, in both clean air and varied ambient background environments. Additionally, we discuss the observed particle-to-particle variations in mass spectral fragmentation patterns, which are inherent to the laser ablation ionization process.

We will demonstrate the utility of custom software to easily identify particles of interest based on single particle mass spectra with high abundance of the target parent ion peak and compare these mass spectra to those obtained by other ionization methods such as electron impact ionization of volatilized aerosols.