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

The collision-induced dissociation (CID) spectra of positive ions of the herbicide diclofop-methyl are reported. The results indicate that for relatively low collision energies (<75 eV, laboratory frame of reference), the distribution of the CID ions of the molecular ion correlates in a qualitative manner with the occurrence of transformation products arising from the degradation of the herbicide in geologic or biofilm 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 transformation products in soil, 4-(2,4-dichlorophenoxy)dehydrophenetole (molecular ion 282) and 4-(2,4-dichlorophenoxy)phenol (molecular ion 254) respectively. At higher collision energies (>45 eV), product ions were 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 source.