Feasibility of detection and identification of individual bioaerosols using laser-induced breakdown spectroscopy.
The detection and identification of individual bioaerosols using laser-induced breakdown spectroscopy (LIBS) is investigated using aerosolized Bacillus spores. Spores of Bacillus atrophaeous, Bacillus pumilus, and Bacillus stearothemophilus were introduced into an aerosol flow stream in a prescribed manner such that single-particle LIBS detection was realized. Bacillus spores were successfully detected based on the presence of the 393.4- and 396.9-nm calcium atomic emission lines. Statistical analyses based on the aerosol number density, the LIBS-based spore sampling frequency, and the distribution of the resulting calcium mass loadings support the conclusion of individual spore detection within single-shot laser-induced plasmas. The average mass loadings were in the range of 2-3 fg of calcium/Bacillus spore, which corresponds to a calcium mass percentage of approximately 0.5%. While individual spores were detected based on calcium emission, the resulting Bacillus spectra were free from CN emission bands, which has implications for the detection of elemental carbon, and LIBS-based detection of single spores based on the presence of magnesium or sodium atomic emission was unsuccessful. Based on the current instrumental setup and analyses, real-time LIBS-based detection and identification of single Bacillus spores in ambient (i.e., real life) conditions appears unfeasible.
Dixon
P B
PB
Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida 32611-6300, USA.
Hahn
D W
DW
D000336:Aerosols / Q000032:analysis*; D000391:Air Microbiology; D001407:Bacillus / Q000648:ultrastructure; D002118:Calcium / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods; D005240:Feasibility Studies; D007834:Lasers; D010316:Particle Size; D013057:Spectrum Analysis / Q000379:methods; D013171:Spores, Bacterial / Q000737:chemistry / Q000302:isolation & purification*; D014131:Trace Elements / Q000032:analysis
D000336:Aerosols; D014131:Trace Elements; D002118:Calcium