文摘
Bioaerosol mass spectrometry is being developed toanalyze and identify biological aerosols in real time.Characteristic mass spectra from individual bacterialendospores of Bacillus subtilis var. niger were obtainedin a bipolar aerosol time-of-flight mass spectrometer usinga pulsed 266-nm laser for molecular desorption andionization. Spectra from single spores collected at anaverage fluence of ~0.1 J/cm2 frequently contain prominent peaks attributed to arginine, dipicolinic acid, andglutamic acid, but the shot-to-shot (spore-to-spore) variability in the data may make it difficult to consistentlydistinguish closely related Bacillus species with anautomated routine. Fortunately, a study of the laser powerdependence of the mass spectra reveals clear trends anda finite number of "spectral types" that span most of thevariability. This, we will show, indicates that a significantfraction of the variability must be attributed to fluencevariations in the profile of the laser beam.