COLLISION-INDUCED DISSOCIATION MASS-SPECTROMETRY OF THE HERBICIDE DICLOFOP-METHYL

The collision-induced dissociation (CID) spectra of positive ions of t he herbicide diclofop-methyl are reported. The results indicate that f or relatively low collision energies (<75 eV, laboratory frame of refe rence), the distribution of the CID ions of the molecular ion correlat es in a qualitative manner with the occurrence of transformation produ cts arising from the degradation of the herbicide in geologic or biofi lm materials. At low collision energies (30-45 eV, laboratory frame of reference), the CID spectra contained a preponderance of product ions at m/z 281 and 253. These product ions correspond to prevalent transf ormation products in soil, 4-(2,4-dichlorophenoxy)dehydrophenetole (mo lecular ion 282) and 4-(2,4-dichlorophenoxy)phenol (molecular ion 254) respectively. At higher collision energies (>45 eV), product ions wer e observed for up to three bond cleavages. The high energy CID product ions correspond to transformation products observed in mature biofilm materials cultivated on the parent herbicide as the sole carbon sourc e.