SIEVE User Guide

B Understanding the Framing Process
Aligning Peaks
Aligning Peaks
In this simplified representation of an experiment comparing three raw files (Controls) to
three raw files (Treatments), SIEVE first consolidates the spectra in a multivariate space:
Retention time versus m/z versus full-scan ms intensity (see Figure 23). Each of the control
samples is represented by green spectral peaks on the map; each of the treatment samples is
represented by red spectral peaks on the map. (In a real set of samples, thousands of peaks
would populate this plane).
Figure 23. SIEVE consolidates the spectra
Notice that there are green outlying peaks to the left of each of the three main clusters. These
peaks represent chromatographic shifts in retention time, requiring that the peaks first be
aligned using the ChromAlign process.
36 SIEVE User Guide Thermo Fisher