Biology Reference
In-Depth Information
FIGURE 1 Two-dimensional map of UHPLC-MS raw data.
different selectivity from chromatographic tech-
niques and is therefore complementary. 11 Small
injection volumes in the nanoliter range are
required, which can constitute an advantage
when a very limited amount of sample is avail-
able but also a limitation in terms of sensitivity.
The coupling of CE with MS is challenging, but
recent analytical developments allowedabroader
implementation in metabolomics. 12
By combining the advantages of these new
analytical tools, high-throughput strategies can
be implemented to assess the metabolic pro
as clinical diagnostics, biomedical research, plant
science, toxicology, microbiology, pharmaceu-
tical research, and environmental science. 15,16
Two strategies can be distinguished, depend-
ing on the number of investigated metabolites,
namely targeted (i.e., pro
ling) and untargeted
approaches (i.e.,
fingerprinting). The former are
dedicated to the analysis of a speci
c subset of
compounds related to a given biochemical
pathway or a particular class of molecules. The
latter intend to provide an unbiased global moni-
toring of metabolites in a biological system
without a priori limitations. Untargeted analytical
approaches are therefore essential to evaluate
biological phenomena in a holistic perspective.
Both strategies are complementary and a sequen-
tial methodology can be carried out. As a starting
point, untargeted approaches are frequently
achieved to derive data-driven hypotheses. Tar-
geted methods are then applied for the reliable
quantitation of relevant metabolites and un-
equivocally con
le
of bio
uids with high sensitivity and selectivity
and a better assignment of metabolites. Although
a prior chromatographic or electrophoretic sepa-
ration step allows an easier and more reliable
metabolite quantitation, no single separative
method is optimal to handle all classes of
compounds. 13 Cross-platform comparisons were
performed to compare and associate data
obtained from LC, GC, and CE experiments. 14
rm compound identities.
TARGETED VERSUS UNTARGETED
STRATEGIES
DATA HANDLING
Metabolomic experimental setups are now
routinely implemented for the discovery of
biomarkers in various application
The high resolution and sensitivity of modern
analytical MS devices allow the
ne character-
ization of biological samples. On the other
fields, such
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