title: Laser power dependence of mass spectral signatures from individual bacterial spores in bioaerosol mass spectrometry.
abstract: Bioaerosol mass spectrometry is being developed to analyze and identify biological aerosols in real time. Characteristic mass spectra from individual bacterial endospores of Bacillus subtilis var. niger were obtained in a bipolar aerosol time-of-flight mass spectrometer using a pulsed 266-nm laser for molecular desorption and ionization. Spectra from single spores collected at an average fluence of approximately 0.1 J/cm2 frequently contain prominent peaks attributed to arginine, dipicolinic acid, and glutamic acid, but the shot-to-shot (spore-to-spore) variability in the data may make it difficult to consistently distinguish closely related Bacillus species with an automated routine. Fortunately, a study of the laser power dependence of the mass spectra reveals clear trends and a finite number of "spectral types" that span most of the variability. This, we will show, indicates that a significant fraction of the variability must be attributed to fluence variations in the profile of the laser beam.
authors.affiliation: Lawrence Livermore National Laboratory, 7000 East Avenue, L-174, Livermore, California 94550, USA.
authors.forename: Paul T
authors.initials: PT
authors.lastname: Steele
authors.forename: Herbert J
authors.initials: HJ
authors.lastname: Tobias
authors.forename: David P
authors.initials: DP
authors.lastname: Fergenson
authors.forename: Maurice E
authors.initials: ME
authors.lastname: Pitesky
authors.forename: Joanne M
authors.initials: JM
authors.lastname: Horn
authors.forename: Gregg A
authors.initials: GA
authors.lastname: Czerwieniec
authors.forename: Scott C
authors.initials: SC
authors.lastname: Russell
authors.forename: Carlito B
authors.initials: CB
authors.lastname: Lebrilla
authors.forename: Eric E
authors.initials: EE
authors.lastname: Gard
authors.forename: Matthias
authors.initials: M
authors.lastname: Frank