Introduction
Scan Types
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1-14 ______________________ Finnigan LTQ Hardware Manual _______________________
1.4 Scan Types
You can operate the LTQ in the following scan types:
• Full scan
• Selected ion monitoring (SIM)
• Selected reaction monitoring (SRM)
• Consecutive reaction monitoring (CRM)
• ZoomScan
Full Scan
The full scan scan type provides a full mass spectrum of each analyte or
parent ion. With full scan, in the last step of mass analysis (the ion scan-out
step) the mass analyzer is scanned from the first mass to the last mass without
interruption.
Full scan scan type provides more information about an analyte than does
selected ion monitoring (SIM) or selected reaction monitoring (SRM), but full
scan does not provide the sensitivity that can be achieved by the other scan
types.
The full scan scan type includes the following:
• Single-stage full scan
• Two-stage full scan
Single-Stage Full Scan
The single-stage full scan type has one stage of mass analysis (n =1 scan
power). With single-stage full scan type, the ions formed in the ion source are
stored in the mass analyzer. Then, these ions are sequentially scanned out of
the mass analyzer to produce a full mass spectrum.
Single-stage full scan experiments can be used to determine the molecular
weight of unknown compounds or the molecular weight of each component in
a mixture of unknown compounds. For example, you need a full scan to
determine the molecular weight of each component of a mixture of unknown
compounds, because you do not know what masses to expect from the
mixture.
To use the SIM or SRM scan type, you need to know what ions you are
looking for before you can perform an experiment. Thus, for SIM or SRM
you can use a full scan to determine the identity of an analyte and obtain its
mass spectrum. Then, you might use SIM or SRM to do routine quantitative
analysis of the compound.
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