Chapter 6 Using Tools and Applications

66.1 Using the Elemental Composition Calculator

This section includes:

•Determining elemental composition

•Setting limits

6.1.1Determining Elemental Composition

This section includes:

•Description

•Determining identity of fragment masses

•Procedure

•Calculating

•Results

•If no results are displayed

•Displaying the theoretical isotope distribution

Description

Determining identity of fragment masses

The Elemental Composition calculator determines possible elemental or amino acid compositions for a given mass. The application then generates a theoretical isotope pattern using the Mass Resolution specified in Basic Peak Detection settings, compares each observed mass and isotope pattern to the theoretical mass and isotope pattern for each possible composition, and reports an isotope match score that reflects how closely they match.

You can also use the Elemental Composition calculator to determine the identity of fragment masses. To do so, set Peak Labels to display Mass Difference From Selected Peak, then specify the mass of the intact molecule. For more information, see “Setting spectrum labels” on page 3-56.

6-2 Applied Biosystems