The separation of Diazinon from its interference in the one-dimensional analysis was also better
when employing GCxGC (Figure 7).
Diazinon
m/z 124 179
Diazinon
1DGC
124 Interference
Figure7.
One-dimensional GC (1DGC) andGCxGC (contour plot on right) analyses for Diazinon in
ash leaves. Thematrix interference that contains substantial 124 ion and is coelutingwith Diazinon
in 1DGC is easily resolved fromDiazinon using GCxGC. The peak containing the 124 ion is the
large red spot in the contour plot.
Conclusions
GC-TOFMS and GCxGC-TOFMS are both powerful techniques for determining pesticides inmatrix
due to automated peak find and spectral deconvolution, and because of the peak capacity increase
affordedwith GCxGC. GCxGC-TOFMS has the potential to produce better spectra for
organophosphate pesticides in themost complexmatrices. TOFMS is the onlymass spectrometer
that has the acquisition speed to support GCxGC, and a full mass spectrum is always obtained.
Acknowledgment
John Gallagher at the United States Department of Agriculture inGulfport, Mississippi provided the
ash leaves extract. The GC columns were from Frank Dorman at Restek Corporation.
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