Laser-Induced Breakdown Spectroscopy Detection and Classification of Biological Aerosols

Abstract

Laser-induced breakdown spectroscopy (LIBS) is examined as a potential method for detecting airborne biological agents. A spectrally broadband LIBS system was used for laboratory measurements on some common biological agent simulants. These measurements were compared to those of common, naturally occurring biological aerosol components (pollen and fungal spores) to determine the potential of LIBS for discriminating biological agents from natural background aerosols. A principal components analysis illustrates that linear combinations of the detected atomic lines, which are present in different ratios in each of the samples tested, can be used to discriminate biological agent simulants from other biological matter. A more sensitive, narrowband LIBS instrument was used to demonstrate the detection of single simulant (Bg) particles in the size range 1-5 microns. Ca, Mg, and Na, which are present in varying concentrations between 0.3 and 11% (by mass) in the Bg particles, were observed in single particles using LIBS.

Laser Induced Breakdown Spectroscopy

“…Hybl et al 356 discussed LIBS as a potential method for detecting airbone biological agents. The authors used the PCA to illustrate that linear combinations of the detected atomic lines, which are present in different ratios in each of the samples tested, can be used to discriminate biological agent simulants from other biological matter.…”

Identification of single microbial particles using electro-dynamic balance assisted laser-induced breakdown and fluorescence spectroscopy

“…This problem was avoided here as the plasma was formed only from particle and from ambient air. In the previous studies by Hybl et al (2003Hybl et al ( , 2006, LIBS spectroscopy has been examined as a potential method for detecting airborne single biological agents. Ca, Na, Mg, and K were typical elements in the LIBS spectra for airborne bacterial and fungal spores, which is in line with our results.…”

“…Na, Ca, and K have strong emission lines within the bandwidth of the spectrometer used in this work. They have been reported acting as dominant compounds in LIBS spectra of bacterial and fungal spores (Hybl et al 2003(Hybl et al , 2006Singh and Rai 2011) and the detection of Na, Ca, and K is not interfered by the elements present in the ambient air. In this study, we measured actual mass concentrations of these elements in single spores.…”

“…It can be used for measuring elemental components in aerosol plumes or in a single aerosol particle (Hybl et al 2003(Hybl et al , 2006J€ arvinen et al 2014). Dutouquet et al (2013) demonstrated LIBS analysis on the particles injected in the radio-frequency plasma discharge and trapped in levitation.…”

“…Fortes et al (2014) reported spectral identification of individual micro-and nano-sized particles by the sequential intervention of optical catapulting, optical trapping, and LIBS having 30% relative standard deviation of LIBS signal for the inspection of Ni microspheres. LIBS also has been explored as a potential method detecting fungal spores and bacteria based on the concentrations of Na, Ca, and K (Hybl et al 2003(Hybl et al , 2006. One of the challenges in the single particle LIBS analysis is the control of particle location and hit rate (Hybl et al 2006;Park et al 2009;Tj€ arnhage et al 2013), but this can be overcome by the use of the electro-dynamic balance (EDB) chamber (J€ arvinen et al 2014).…”