instrument can detect as many as several hundred
SRM transitions. The SRM condition set, which
comprises retention time, transition, repeller
voltage (sampling cone voltage) and ion-accel-
erating voltage for fragmentation, must be opti-
mized for each metabolite to be analysed. If SRM
conditions for a broad range of metabolites are
available, large-scale multiple SRM analysis will
provide a novel technique for metabolomics.
Furthermore, given that SRM is originally a
method for targeted analysis, reproducible anal-
ysis can be implemented if the analytical
conditions and data obtained are validated with
authentic compounds and case studies using
several plant materials. The SRM conditions for
approximately 1,000 authentic compounds were
optimized by liquid handling systems andflow
injection analysis using TQ-MS and UPLC-TQ-
MS (Yamazaki et al. 2013 ). This analytical sys-
tem, named widely targeted analysis, is practical
for plant metabolomics and offers several
advantages including reproducible detection of
various (more than 500) metabolites, femtomole-
level ultra-high sensitivity and high throughput(a)(b)(c)Fig. 16.1 Recent advances in metabolomics for LC
separation and MS detection.aSub-2-micron column of
UPLC provides peak widths of a few seconds (upper
panel), the 3-micron column of conventional LC provides
peak widths of more than 10 s (lower panel).bUsing
high-sensitivity scanning of UPLC-QTOF-MS, almost all
LC-separated peaks can be assigned to MS (precursor
ions representing molecular weight) and MS/MS data
(product ions).cIn SRM analysis using a triple quadru-
pole (Q1,Q2andQ3) instrument, the targeted metabolite
can be selectively detected by duplicated MSfiltrations,
the precursor ion inQ1and one of the product ions inQ3
(after fragmentation inQ2)176 Y. Sawada and T. Aoki