Signal variation in single particle aerosol mass spectrometry

Rapid and accurate detection of airborne micro-particles is currently an important problem in national security. One approach to such detection, bioaerosol mass spectrometry (BAMS), is currently under development at Lawrence Livermore National Laboratory. BAMS is a type of single particle aerosol mass spectrometry that rapidly records dual-polarity mass spectra of aerosolized micro-particles. However, the accuracy of the BAMS system is limited by various uncertainties, resulting in shot-to-shot variations in the mass spectra. I found that the variations in mass peak areas in BAMS spectra were significantly larger than those predicted by Poisson statistics based on the mean number of detected ions. Furthermore, these variations were surprisingly consistent as a function of peak area among synthetic, organic, and biological samples. For both positive and negative ions, the standard deviation in a peak's area was approximately proportional to the mean value of that area to the 0.9 power. Using the consistency of this data, I also developed a novel method for quantitatively evaluating the similarity between mass spectra using a chi-square factor. Peak area variations in other single particle aerosol mass spectrometers may be similarly analyzed and used to improve methods for rapid particle identification.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Physics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2007

Author dc:creator

• Wissner-Gross, Zachary Daniel

Advisor dc:contributor.advisor

• Matthias Frank and Young Lee.

• Physics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/40921

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/40921