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For MS/MS data, the intensity is associated with all masses, precursor, and fragment ions.
When data is viewed as a spectrum, mass-specific information about a compound is obtained. A spectrum looks
at a particular peak and provides
m/z
values of the corresponding compound, which can be used to find more
specific information. For example, a spectrum shows all of the masses that make up a peak, including the intensity
of each mass.
Spectral intensities may change, but the masses are fixed because the mass of a compound does not change.
There are two ways to generate spectral data:
• If only one scan is acquired, then the data is shown as a spectrum.
• From a chromatogram.
A typical spectrum is shown with the molecular weight, labeled with the
m/z
(mass-to-charge ratio), on the x-axis.
The intensity is shown on the y-axis.
Quantitative Analysis
Quantitative analysis is used to find the concentration of a specific substance in a sample. By analyzing an unknown
sample and comparing it to other samples containing the same substance with known concentrations (standards),
the software can calculate the concentration of the unknown sample. The process involves creating a calibration
curve using the standards and then calculating the concentration for the unknown sample. The calculated
concentrations of each sample are then available in a Results Table.
Integration
In LC-MS/MS data, integration refers to obtaining the area under a curve for the peak associated with a specific
compound. Through the development of a processing method which specifies the mass transitions, expected
retention times, internal standards, integration, and regression parameters, the software is able to automatically
integrate peaks for a given set of samples.
The compilation of quantitative or qualitative information for a given set of samples is called a Results Table. Refer
to
.
Results Tables
A Results Table is a compilation of the quantitative and qualitative information associated with a set of samples.
It includes, among others, the calculations for concentration and accuracy determined as a result of interpolating
the calibration (standard) curve. The library search results, formula finding results, and other qualitative analysis
results are also available in the Results Table. Area, height, and other numerical characteristics can be shown. The
number and type of columns in the Results Tables can be edited for simplified viewing.
Calibration Curves
A calibration curve, also know as a standard concentration curve, is a method for determining the concentration
of a substance in an unknown sample by comparing the unknown sample to a set of standard samples of known
System User Guide
SCIEX X500 QTOF System
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Principles of Operation