The
most serious inconvenience of the method is that
monuron and monolinuron formed the same isocyanate
(tr=6.795 min) and it was also the case
for linuron and diuron (tr=7.496 min). Therefore,
as no chromatographic signal for non-degraded
monuron and diuron was obtained and,
taking into account the above mentioned coincidence,
only qualitative assays for these two herbicides
could be carried out in the absence of
monolinuron and linuron. Thus, only the PUHs
providing parent compounds were selected for
further experiments.