99 / 302
5
Thermo Scientific Poster Note
•
PN63619_E 06/12S
Conclusion
This poster demonstrates:
Online pre-concentration and extraction for 1mL inject
level.
The quantitation of HR/AM data using TraceFinder sof
Plus Orbitrap instrument.
Spectral confirmation of MS
2
spectrum collected in th
quantitation data using ExactFinder software.
Ability to quantitate and confirm samples in the same
in water samples.
Acknowledgements
We would like to thank Paul Yang from the Ontario Ministry f
supplying the antibiotic standards for this analysis.
All trademarks are the property of Thermo Fisher Scientific and its subsidiaries.
encourage use of these products in any manners that might infringe the intellec
Spectral Confirmation
To add additional confirmation to the antibiotics detected in the samples, spectral
confirmation of the MS
2
spectrum collected in the HCD cell was performed using
ExactFinder™ software. Samples were submitted to the software after acquisition. The
MS
2
spectra were searched against the built-in Environmental and Food Safety and
Clinical Research spectral libraries. These libraries contain MS
2
spectra collected on
Orbitrap instruments. Because all Orbitrap platform mass spectrometers are
compatible, they provide identical spectra.
The spectral match for the antibiotic trimethoprim is shown in Figure 4. This
comparison is from the HCD MS
2
spectrum of the calibration standard corresponding
to a concentration of 80 pg/mL. The top spectrum is the library reference spectrum.
The bottom spectrum is the collected sample spectrum. The library reference
spectrum is cleaner, because it was collected using a Thermo Scientific LTQ Velos Pro
Orbitrap mass spectrometer by direct infusion. Thus, there is much less background,
no co-eluting peaks, or matrix to generate extraneous ions. Nevertheless, the two
spectra match in the main fragment peaks, as well as the protonated molecular ion at
m/z
= 291.1446 amu. This spectral confirmation helps to eliminate the possibility of
false-positives, and can be used for identification point scoring systems.
TABLE 2. List of antibiotics analyzed with their theoretical masses, LOQs and
reproducibility
Compound
Theoretical Mass (
m/z)
LOQ (pg/mL)
% RSD at LOQ
Carbamazepine
332.14050
0.2
8.90
Erythromycin
734.46852
40.0
14.30
Ketoprofen
255.10157
1.0
9.90
Norethindrone
299.20056
1.0
13.50
Roxithromycin
837.53185
9.9
4.20
Sulfachloropyridazine
285.02075
1.0
7.30
Sulfadimethoxine
311.08085
0.4
4.80
Sulfamerazine
265.07537
0.6
4.90
Sulfamethazine
279.09102
1.0
3.45
Sulfamethizole
256.02089
1.0
6.30
Sulfamethoxazole
254.05939
1.0
6.60
Sulfathiazole
271.03179
0.6
3.60
Trimethoprim
291.14517
1.6
13.10
FIGURE 4. Spectral comparision of the MS
2
spectrum of
trimethoprim obtained at a concentration of 80 pg/mL. T
spectrum is the top spectrum, the lower spectrum is fro
comparison was performed with ExactFinder software.