Persistent degradation products by bromoxynil and ioxynil
8 Jørgensen LF, Groundwater monitoring 2003 (in Danish).
Geological Survey of Denmark and Greenland, Ministry of
the Environment, Copenhagen, Denmark (2003).
degraded bromoxynil in the low concentrations seen
with Variovorax sp. 11 402 in the present study.
9 Jeannot R, Sabik H, Sauvard E and Genin E, Application of liq-
uid chromatography with mass spectrometry combined with
photodiode array detection and tandem mass spectrometry
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879:51–71 (2000).
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mation of dichlobenil to 2,6-dichlorobenzamide (BAM) by
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4
CONCLUSION
The usefulness and performance of the LC-MS/MS
method for Kd/Kdes determination and degradation
studies of bromoxynil and ioxynil has been demon-
strated. Using the isocratic LC-MS/MS method devel-
oped, simultaneous detection and quantification of
bromoxynil, ioxynil and their corresponding amides
and acids can be obtained within 14 min (Fig. 2). Bro-
moxynil and ioxynil had a low DT50 when degraded
by Variovorax sp. 11 402. Total mineralization by this
bacterial culture cannot be expected as persistent
degradation products, BrAM and IAM, were pro-
duced. As indicated by QSAR models, the reason for
the degradation inhibition may be related to steric
or electrostatic potential properties resulting from the
presence of halogen atoms in the ortho and meta posi-
tions. Considering the widespread detection of BAM
in Danish monitoring systems, it is highly relevant to
take into account a possible similar problem caused
by the formation of the persistent compounds BrAM
and IAM. If these transformation products are also
produced by the indigenous bacteria in soil, the poten-
tial degradation products can potentially leach to the
groundwater, as seen with BAM. This calls for further
investigations of the degradation products BrAM and
IAM in groundwater and soil.
12 McKillop
A
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a batch equilibrium method.
OECD Guidelines for Testing Chemicals, TG 106, Paris,
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ACKNOWLEDGEMENTS
The authors would like to thank Anne Goldbeck
for advice with the synthesis and Trine Henriksen
for introduction to the LC-MS/MS instrument. The
Immunalyse Project (Grant No. 9901188) and the
Danish Research Council (RECETO) financed the
degradation study.
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DOI: 10.1002/ps