FormNo. 203-821-258 02/05-REV0
LECO is a registered trademark of LECO Corporation
2
MS: LECO Pegasus TOFMS
Ionization:
Electron ionization at 70 eV
Source Temperature: 225°C
StoredMass Range: 45 to 550 u
Acquisition Rate:
100 spectra/sec.
DataProcessing
LECOChromaTOF
®
softwarewith automated peak find and spectral deconvolution.
Results andDiscussion
Figure 1 simultaneously illustrates the complexity of the ash leaves extract and the power of
automated peak find and spectral deconvolution afforded by the fast acquisition capability and
spectral reproducibility of TOFMS. Thematrix peaks, especially the off-scalem/z 124, hide the
orange peak representingDiazinon (approximately 50 pg), and a caliper spectrum at the Diazinon
peak apex is representative of the background from the ash leaves. Note that the deconvoluted
mass spectrummatches nicely with a reference spectrum for Diazinon.
Deconvoluted
spectrum
Reference
spectrum
Raw
spectrum
Figure1.
Chromatogram of 50 pg Diazinon (orange peak) in an ash leaves extract plottedwith
ions representing thematrix. The raw spectrum taken at the peak apex for Diazinon is
representative of thematrix interferences. The deconvoluted TOFmass spectrummatches well with
the reference spectrum.
A similar chromatographic situation exists for Malathion in the complex ash leaves extract as shown
in Figure 2. Again, the raw spectrum taken at the peak apex for Malathion (approximately 125 pg)
ismainly showing ions for thematrix interferences, particularly 167, the turquoise off-scale peak in
Figure 2. The deconvoluted spectrum, while not perfect (it still contains some 167 ion), shows a
similarity of 806 (out of 999) against the first-hit library spectrum for Malathion.
