Desorption/Ionization Fluence Thresholds and Improved Mass Spectral Consistency Measured Using a Flattop Laser Profile in the Bioaerosol Mass Spectrometry of Single Bacillus Endospores
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- 作者：Paul T. Steele ; Abneesh Srivastava ; Maurice E. Pitesky ; David P. Fergenson ; Herbert J. Tobias ; Eric E. Gard ; and Matthias Frank
- 刊名：Analytical Chemistry
- 出版年：2005
- 出版时间：November 15, 2005
- 年：2005
- 卷：77
- 期：22
- 页码：7448 - 7454
- 全文大小：267K
- 年卷期：v.77,no.22(November 15, 2005)
- ISSN：1520-6882
文摘
Bioaerosol mass spectrometry is being developed toanalyze and identify biological aerosols in real time. Massspectra of individual Bacillus endospores were measuredwith a bipolar aerosol time-of-flight mass spectrometer inwhich molecular desorption and ionization were producedusing a single laser pulse from a Q-switched, frequency-quadrupled Nd:YAG laser that was modified to have anapproximately flattop profile. The flattened laser profileallowed the minimum fluence required to desorb andionize significant numbers of ions from single aerosolparticles to be determined. For Bacillus spores, thisthreshold had a mean value of ~1 nJ/
m2 (0.1 J/cm2).Thresholds for individual spores, however, could apparently deviate by 20% or more from the mean. Thresholddistributions for clumps of MS2 bacteriophage and bovineserum albumin were subsequently determined. Finally,the flattened profile was observed to increase the reproducibility of single-spore mass spectra. This is consistentwith the general conclusions of our earlier paper on thefluence dependence of single-spore mass spectra and isparticularly significant because it is expected to enablemore robust differentiation and identification of singlebioaerosol particles.
m2 (0.1 J/cm2).Thresholds for individual spores, however, could apparently deviate by 20% or more from the mean. Thresholddistributions for clumps of MS2 bacteriophage and bovineserum albumin were subsequently determined. Finally,the flattened profile was observed to increase the reproducibility of single-spore mass spectra. This is consistentwith the general conclusions of our earlier paper on thefluence dependence of single-spore mass spectra and isparticularly significant because it is expected to enablemore robust differentiation and identification of singlebioaerosol particles.