Sample Preparation in Global Metabolomics of Biological Fluids and Tissues - Proteomic and Metabolomic Approaches to Biomarker Discovery - page 69

a red blood cell metabolome study, only about
57% of metabolite features exhibited reasonable
linearity upon dilution. 68

and fractionation steps. However, one recent
study shows that use of HPLC fractionation fol-
lowed by chemical derivatization to increase
hydrophobicity prior to LC-MS analysis signifi-

finding shows
that current measures, such as the number of
metabolite features and method precision
(expressed as median RSD), are not fully suffi-

This

-
cantly improved metabolite coverage in urine:
1,218 metabolites were detected using a 1D
approach versus 3,564 metabolites detected
using a 2D approach with 7 fractions. 114 This
example shows the potential utility of prefractio-
nation techniques, and such approaches may
become more prevalent in the future, at least
for

-
cient to ensure good analytical data quality.
Data for additional parameters summarized in
Figure 1 is urgently needed. Finally, Koek et al.
provided an excellent discussion of quality
control and method validation strategies for
GC-MS metabolomics, 113 but the proposed strat-
egies such as the addition of different labeled
metabolites at each step from sampling until
injection could be immensely useful across
different analytical platforms in order to eval-
uate/document/control method performance
at each stage of sample preparation.
For deeper metabolome studies, future exper-
imental designs may consider inclusion of two or
more highly complementary methods in order to
increase the information content of the acquired
data.

comprehensive cataloging of various

metabolomes.

Acknowledgment
Portions of text in this chapter were reprinted/adapted from
ref. 10 , with kind permission from Springer Science þ Busi-

ness Media.

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ling of human amniotic

field. Another
interesting trend to note is that fractionation is
not generally used in global metabolomic studies
in contrast to proteomics, in which enormous
sample complexity demands routine depletion analysis II. Preparation of