The mean recoveries of pesticides from fortified plant
samples were within 73–120%, when method I and
Florisil cleanup was used (Table 5), with the exception
of p,p-DDT which showed an extra high recovery
(>150), which is most probably due to matrix interferences.
Formothion (18%) and pyrazophos (30%) showed
low recoveries that could be explained on the basis of
their high polarity as discussed earlier. The interesting
finding here is that the recovery of tetramethrin was
73%. This might be explained once again on the basis of
polarity and interactions between analytes and coextractives
from the plant with the adsorbent (Florisil),
since aniseed is known to contain a variety of constituents
(Newall et al., 1996), and the presence of coextractives
with polarities higher than that of tetramethrin
could have caused more preferential adsorption of these
coextractives to Florisil, than tetramethrin, which might
caused tetramethrin to elute from Florisil column in
higher percentage. It is also possible that some constituents
in the P. anisum extract might have protected
tetramethrin from being degraded. When method II and
Florisil cleanup was used with P. anisum samples, the
mean recoveries were in the range 70–100% (Table 6)
including these of p,p-DDT and tetramethrin, with the
exception of formothion (14%) and pyrazophos (10%).
The mean recoveries of pesticides from fortified plantsamples were within 73–120%, when method I andFlorisil cleanup was used (Table 5), with the exceptionof p,p-DDT which showed an extra high recovery(>150), which is most probably due to matrix interferences.Formothion (18%) and pyrazophos (30%) showedlow recoveries that could be explained on the basis oftheir high polarity as discussed earlier. The interestingfinding here is that the recovery of tetramethrin was73%. This might be explained once again on the basis ofpolarity and interactions between analytes and coextractivesfrom the plant with the adsorbent (Florisil),since aniseed is known to contain a variety of constituents(Newall et al., 1996), and the presence of coextractiveswith polarities higher than that of tetramethrincould have caused more preferential adsorption of thesecoextractives to Florisil, than tetramethrin, which mightcaused tetramethrin to elute from Florisil column inhigher percentage. It is also possible that some constituentsin the P. anisum extract might have protectedtetramethrin from being degraded. When method II andFlorisil cleanup was used with P. anisum samples, themean recoveries were in the range 70–100% (Table 6)including these of p,p-DDT and tetramethrin, with theexception of formothion (14%) and pyrazophos (10%).
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