Chromatography without spectral detectors
such as diode array, mass-spectral or fast scanning is unthinkable today. Recorded
with such detectors, a chromatogram consists of spectra (set
of measurements for different wavelengths, masses, etc.) evolved over time. Another way to get a multi-channel chromatogram is
to measure several responses from different detectors, connected
consecutively or in parallel, such as UV+RI+radioactivity
detector in LC or TCD+FID+ECD+FID in GC. In this case, the
spectrum is a set of responses of all detectors in use at
one time.
Factor analysis considers
a region of multi-channel chromatogram by comparing all the spectra in the region
using linear algebra.
Factor analysis of the chromatographic peak shows whether the substance being eluted is homogeneous or not. If the
peak originates from one component, spectra within the whole
peak will be similar. If spectra within the peak are significantly
different, the peak consists of two or more overlapped peaks.
The main goal of factor
analysis is computational separation
of the peaks that are not separated by chromatography.
Chrom&Spec
uses self-modeling factor analysis which enables pure component detection. This approach
is based on the concept of “best local purity”
for spectra of the peak. Using the spectra obtained, the full
elution profile of every component can be reconstructed.
In many cases factor analysis is a very precise method, allowing
not only detection of an extra component, but also providing the correct quantification
of the extra component.
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