Agriculture Reference
In-Depth Information
SRM con
MS platforms. The multiscreening step
consisted of full scan accurate MS techniques (e.g., TOF
rmation using the LC
-
QqQ
-
-
MS or Orbitrap MS)
and required an additional MS/MS-based quanti
rmation step.
However, HRMS has been demonstrated to be an attractive tool for trace analyte
detection by screening analysis, as well as for con
cation and con
rmation and quanti
cation in
challenging matrices.
Currently, available resolution achieved with HRMS means that its selectivity
exceeds that provided by currently used LRMS instruments for con
rmation.
HRMS has been shown to be capable of detecting compounds at trace concentra-
tions and identifying coeluted compounds, and can potentially suppress matrix
compounds. Additionally, because HRMS instruments acquire full scan accurate
data, they allow retrospective data analysis based on an
aposteriori
hypothesis.
This permits the detection of target compounds as well as the monitoring of
metabolites or degradation products, which are not commercially available for the
analytes investigated. Thus, it has been demonstrated that LC
HRMS opens the
possibility of identifying target and nontarget compounds and improves reliability
and robustness. In consequence, laboratory throughput is enhanced because the
samples do not need to be injected again if the monitoring of additional analytes is
requested.
Additionally, HRMS permits the elucidation of the elemental composition of
analytes based on exact masses and isotopic patterns (RIA). For reliable structural
assignment, high resolution (
-
10,000 FWHM) is recommended and the accuracy of
the isotope intensities must be excellent
>
fits for
substances without highly characteristic isotope patterns (compounds without Cl
or Br atoms) as is the case of some families of VDs (such as macrolides and
quinolones).
On the other hand, it can be concluded that HRMS analyzers such as the
Orbitrap, and to a lesser extent, TOF
to allow elemental formula
-
MS or QqTOF
-
MS, are also suitable for
quanti
cation, obtaining performance characteristics similar to conventional
LRMS analyzers, where a large number of analytes have to be detected and
quanti
ed. Therefore, UHPLC coupled with TOF
-
MS, QqTOF
-
MS, single-stage
Orbitrap
MS offers unsurpassed performance for screen-
ing purposes. They can also effectively provide quantitative information and are
accurate and sensitive enough to differentiate between positive and negative
samples in VDs.
-
MS, and LQT
-
Orbitrap
-
ACKNOWLEDGMENTS
The authors gratefully acknowledge the Spanish Ministry of Economy and Competitiveness
(MINECO) and FEDER for
financial support (Project Ref. AGL2010-21370). M.M.A.L.
acknowledges her grant (F.P.U.) (MINECO, Ref. AP2008-02811). P.P.B gratefully acknowl-
edges personal funding through the Agrifood Campus of International Excellence, ceiA3
(Spanish Ministry of Education, Culture and Sport). R.R.G. is also grateful for personal funding
through the Ramón y Cajal Program (MINECO-ESF).
