title: Development of size-selective sampling of Bacillus anthracis surrogate spores from simulated building air intake mixtures for analysis via laser-induced breakdown spectroscopy.
abstract: Size-selective sampling of Bacillus anthracis surrogate spores from realistic, common aerosol mixtures was developed for analysis by laser-induced breakdown spectroscopy (LIBS). A two-stage impactor was found to be the preferential sampling technique for LIBS analysis because it was able to concentrate the spores in the mixtures while decreasing the collection of potentially interfering aerosols. Three common spore/aerosol scenarios were evaluated, diesel truck exhaust (to simulate a truck running outside of a building air intake), urban outdoor aerosol (to simulate common building air), and finally a protein aerosol (to simulate either an agent mixture (ricin/anthrax) or a contaminated anthrax sample). Two statistical methods, linear correlation and principal component analysis, were assessed for differentiation of surrogate spore spectra from other common aerosols. Criteria for determining percentages of false positives and false negatives via correlation analysis were evaluated. A single laser shot analysis of approximately 4 percent of the spores in a mixture of 0.75 m(3) urban outdoor air doped with approximately 1.1 x 10(5) spores resulted in a 0.04 proportion of false negatives. For that same sample volume of urban air without spores, the proportion of false positives was 0.08.
authors.affiliation: U.S. Environmental Protection Agency (E305-01), Office of Research and Development, Research Triangle Park, North Carolina 27711, USA. snyder.emily@epa.gov
authors.forename: Emily
authors.initials: E
authors.lastname: Gibb-Snyder
authors.forename: Brian
authors.initials: B
authors.lastname: Gullett
authors.forename: Shawn
authors.initials: S
authors.lastname: Ryan
authors.forename: Lukas
authors.initials: L
authors.lastname: Oudejans
authors.forename: Abderrahmane
authors.initials: A
authors.lastname: Touati
mesh_terms: D000336:Aerosols; D000388:Air; D000389:Air Conditioning; D000393:Air Pollutants / Q000737:chemistry; D001408:Bacillus anthracis / Q000737:chemistry / Q000254:growth & development / Q000302:isolation & purification*; D023482:Bioterrorism / Q000517:prevention & control; D002947:Cities; D005189:False Positive Reactions; D007834:Lasers; D010047:Ovalbumin / Q000737:chemistry; D010316:Particle Size; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D013171:Spores, Bacterial / Q000737:chemistry / Q000302:isolation & purification*; D001335:Vehicle Emissions
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D001335:Vehicle Emissions; D010047:Ovalbumin