Chapter 6 Using Tools and Applications

10.

Select the calculation mode:

6

 

• 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.

Add and subtract examples

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.

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

(C42H60O30 + 2Na)/2

Group type— Na

 

Group Count/Charge— 2

 

Add

 

 

 

6-16 Applied Biosystems