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4th HR-AMS Clinic, Boulder,CO Paola Massoli Aerodyne Research

1) Adding new ions into PIKA to account for marine organic aerosol ion fragments 2) Precautions for deciding when N containing ions  peaks in fits are real or not. 4th HR-AMS Clinic, Boulder,CO Paola Massoli Aerodyne Research. 1) Adding new ions into PIKA to account for

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4th HR-AMS Clinic, Boulder,CO Paola Massoli Aerodyne Research

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  1. 1) Adding new ions into PIKA to account for marine organic aerosol ion fragments 2) Precautions for deciding when N containing ions  peaks in fits are real or not 4th HR-AMS Clinic, Boulder,CO Paola Massoli Aerodyne Research

  2. 1) Adding new ions into PIKA to account for marine organic aerosol ion fragments

  3. HR-ToF data collected (V mode)in marine environment NaCl (m/z 58) Diff ~ 90 Hz Broad shape due to surface vaporization

  4. …..and its isotope (Na37Cl, 1/3 of intensity of parent ion)

  5. Found several “unknown”peaks in the MSLikely halide clusters (Cl, Br) containing metals because they are on the left side of the m/z (also in closed, surface vaporization)

  6. Like this at m/z 125 (MnCl2)

  7. How do I make sure my guessed mass is right ? Use the isotope ratios of Cl, Br etc…. If MnCl2 is real, there should be 1) MnClj37Cl at mz 127 (UMR value) 2) Mnj37ClCl at mz 129 (UMR value)

  8. MnClj37Cl

  9. Need to modify the HR ion lists

  10. Still some unknowns….

  11. Use mmass.exe (public software)

  12. …once you fitted all the peaks (and properly modified HR batch, family and frag tables)

  13. 2) Precautions for deciding when N containing ions  peaks in fits are real or not

  14. Average todo wave w/ C3H2N

  15. No C3H2N….there seems to be a residual signal to be fitted

  16. One run….no clear sign that C3H2N should be fitted

  17. Look at Ar (m/z 40)

  18. Look at SO (m/z 48)

  19. Bottom line • N containing peaks are small, and they usually fall in the tail of big signals. The “peak broadening” can be an issue here • Look at average todo wave vs single run • Evaluate peak shape using Ar and SO • Look at time series and their noise • Loot at correlation plots between main peak and small ion (eg C4H4 and C3H2N of slide 16) to see if they co-vary: if yes, the small ion is not real • Look at average todo wave vs single run • Use W mode if you have it 

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