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Chapter 6 Using Tools and Applications
6-16 Applied Biosystems
6
10. Select the calculation mode:
• FWHM—Resolves peaks using the full peak width
at peak half height.
• 10% Valley—Resolves peaks to a 10 percent
valley.
11. Set the Threshold %. Signal intensity below this percent
intensity is not included in the calculation or display.
NOTE: Setting Threshold % too high distorts the
isotope pattern.
12. Click Calculate.
The theoretical isotope distribution is displayed in the
Spectrum window with an ISO trace label and the
elemental formula, or the amino acid, DNA, or RNA
sequence.
The result is displayed in the Result tab in the Output
window. For more information, see “Evaluating traces”
on page 6-18.
Add and subtract
examples
The following examples illustrate how the software adds and
subtracts groups to or from an elemental formula, and how it
applies the charge state field.
To calculate a theoretical isotope distribution for doubly
sodiated β-cyclodextrin with a +2 charge state (m/z 545)
With these parameters specified
The software performs
this calculation
Formula
*
—C42H60O30 (C
42
H
60
O
30
+ 2Na)/2
Group type—Na
Group Count/Charge—2
Add