AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
State-of-Art Toolbox for High Resolution De-convolution of Ion-Cluster Signal from Time-of-Flight Mass Spectrometry Data
HEIKKI JUNNINEN, Gustaf Lönn, Mikael Ehn, Siegfried Schobesberger, Tuukka Petäjä, Douglas Worsnop, Markku Kulmala, University of Helsinki
Abstract Number: 645 Working Group: Instrumentation and Methods
Abstract Recent developments in atmospheric measurement techniques that include a time-of-flight mass spectrometry (TOFMS) as a mean for separation and detection are increasing in number. Many of the application share the same mass spectrometer that is customizable for a specific needs and has been proven to be robust enough even for a field measurements. The TOFMS has the resolution power of 3000 to 6000 Th/Th, has mass accuracy less than 20 microTh/Th, and is built by Tofwerk AG.
Examples of application that are commercially available or built by research groups are; atmospheric pressure interface TOFMS (APiTOF - for measuring ambient ions), atmospheric pressure chemical ionization (NO3-CI-APiTOF - for sulphuric acid detection with nitrate ionization; H-CI-APiTOF – proton transfer for amine and ammonia detection), reduced pressure chemical ionization (Ac-CI-APiTOF – acetic acid ionization for detection of weak acidic molecules; PTR-TOF – proton transfer for VOC detection), aerosol instruments (TD-CIMS, thermal desorption aerosol collection of 10-30nm particles, laser-AMS – for laser desorption of 10-30nm particles, MOVI-CIMS – simultaneous sampling of aerosol and gaseous sample).
Common for the all techniques listed above is the same mass spectrometer and the same data format and thus, the same data analysis requirements and needs. Work presented here provides common tools for initial steps of data analysis of time of flight mass spectrometry data. Each sampling and ionization technique has a specific post-processing and calibrations but the raw data acquired by the mass spectrometer is the same for all.
Toolbox presented here features all the essential steps required for high resolution data analysis, including custom time averaging and filtering of raw data, robust mass calibration, defining instrument parameters, unit mass resolution stick calculations and high resolution peak fitting. The later includes custom peak shape and isotope locking. In the presentation these steps will be explained in detail and real world examples will be used to illustrate the process.