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A Strategy for an Unknown Screening Approach on Environmental Samples using HRAM Mass Spectrometry
comparison.
B
ations of a suspect screen
ow was run. For this the
sferred to the screening
itioned component
settings and parameters
inder to SIEVE
detection process could be
lt, 5000 components were
ntains all components
e, refinement of this list was
process, all samples were
ter sample, so a simple filter
atrix and background
ving 1829 components in
pal component analysis to
water samples were closely
e (surface water 1, see Fig.
nt in its content, so the filter
uld be further refined.
filtering for significant
surfacewater1
tapwater
high resolving power of R = 70,000 @
m/z
200 used in this
analysis.
FIGURE 7. Importance of sufficient resolution for
unambiguous identification of components: The
monoisotopic signl (A) and the first isotope signal (B)
are surrounded by matrix signals of similar intensity
which are only separated by means of the high
resolving power used.
Since all final processing was done in one application, the
results of target, suspect and unknown screening could
easily be combined into one result, making result reporting
and archiving one single step. Since all data transfer
between the two applications is fully automated, Fig. 8
shows a short selection of compounds which had not been
part of the initial target screening, but were found in the
unknown screening process.
FIGURE 8. Selection of additional contaminants not
present in previous target and suspect screen.
Compound Name Formula
m/z (Apex) m/z (Delta (ppm)) RT (Measured) Isotopic Pattern Score (%)
Bisoprolol
C18H31NO4
326.2330
0.57
5.12
100
Candesartan C24H20N6O3 441.1671
-0.50
6.56
100
Carbofuran
C12H15NO3
222.1127
-0.19
5.18
98
Dibenzylamine C14H15N
198.1277
-0.66
7.31
98
Irbesartan
C25H28N6O 429.2401
-0.03
6.45
100
Loxoprofen
C15H18O3
247.1332
0.45
5.52
85
Mexacarbate C12H18N2O2 223.1443
-0.06
5.53
96
Oxazepam C15H11ClN2O2 287.0584
0.48
6.29
96
Propiconazole C15H17Cl2N3O2 342.0774
0.21
7.43
89
Tramadol
C16H25NO2
264.1961
0.10
4.35
100
Conclusion
In this example of environmental analysis we could show
that it is possible to enhance the capabilities of target and
suspect screening with its limitations by a streamlined
general unknown screening with a high degree of
automation from within one application. The resolving
power of the Exactive Plus bench top Orbitrap MS system
is the driving force behind the selectivity and reliability of
the obtained results because this serves for the separation
of the analyte peaks from background and matrix signals.
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Presented at RAFA, Prague, Czech Republic, Nov 5-8, 2013.