Sample Preparation in Global Metabolomics of Biological Fluids and Tissues - Proteomic and Metabolomic Approaches to Biomarker Discovery - page 51

ABBREVIATIONS

or capillary electrophoresis (CE-MS) in various
con

gurations further augments metabolite
coverage to hundreds or even thousand(s) of
additional metabolites in a single analysis.
Inaddition to the selection of the analytical plat-
form, the choice of sample preparation strategy
extensively contributes to the success of a given
experiment because it affects both the observed
metabolite pro

DBS dried blood spot or dried bio uid spot

CE capillary electrophoresis
CSF cerebrospinal uid

EDTA ethylenediaminetetraacetic acid
ESI electrospray ionization
GC-MS gas chromatography-mass
spectrometry
HILIC hydrophilic interaction chromatography
HPLC high-performance liquid
chromatography
HUSERMET Human SerumMetabolome project
LC-MS liquid chromatography-mass
spectrometry
NMR nuclear magnetic resonance
PBS phosphate buffered saline
PCA principal component analysis
RSD relative standard deviation
SPME solid-phase microextraction
SPE solid-phase extraction
TFC turbulent

le and data quality. 7 e 10 The capa-
bilities and limitations of sample preparation
method used in a given study can compromise
the accuracy of the biological interpretation, as
shown in several recent studies in which both
up- or downregulation ofmetabolites couldbedis-
torted 11 and/or contradictory biological interpre-
tation of active metabolite pathways could be
made depending on the extraction method
chosen. 12 In the latter study, 17 out of 69 pathways
showed contradictory results with different
extractionmethods, demonstrating the truly enor-
mous in uence that the choice of sample prepara-

tionmethod has on the observedmetabolome and
accurate biological interpretation in discovery
metabolomics. Therefore, the focus of this chapter
is to critically discuss strengths, weaknesses, new
trends, and future directions of various sample
preparationmethods used in global metabolomics
of biological

ow chromatography
UHPLC ultra high-performance liquid
chromatography

INTRODUCTION

fluids and tissues.

The main objective of global metabolomics or
untargeted metabolite pro ling studies is to

successfully analyze as many small molecular
weight species as possible in a single experiment.
A typical biological

AN IDEAL SAMPLE
PREPARATION METHOD FOR
GLOBAL METABOLOMICS ?

fluid sample is expected to
contain more than 1,000 metabolites, even by
the most conservative accounts. 1 e 3 The large
number of metabolites and their chemical diver-
sity and enormous dynamic range of concentra-
tions (11 orders of magnitude observed for
human serum 3 ) necessitate the use of multiple
analytical techniques, with nuclear magnetic reso-
nance (NMR) and mass spectrometry (MS) being
the most dominant. NMR can typically detect
about 25 to 100 of the most abundant metabo-
lites, 3 e 6 whereas the combination of MS with
liquid (LC-MS), gas chromatography (GC-MS),

An ideal sample preparation method for the
metabolomic analysis of biological samples
should (1) be unselective, (2) be simple and fast
with a minimal number of steps, (3) be reproduc-
ible, and (4) incorporate a metabolism quenching
step, 13 as shown in Figure 1 . Clearly, no single
procedure meets all of these requirements, so
a compromise between competing parameters
is often made. Thus, to understand the limita-
tions and performance of the method used in
a given study, Figure 1 also summarizes