The performance of the proposed method for
environmental samples was assessed in three types
of weed plants (Chenopodium album, Raphanus
raphanistrum and Capsella bursapastoris) growing
in crop and non-crop lands where the PUHs
studied are usually applied. Plants were fortified
at three concentration levels according to the
procedure described in Section 2.3. Initially, 1-g
of each plant was extracted with 10 ml of 10−3
mol l−1 HNO3 although the amount of sample
could have been increased up to 3 g by extracting
with 20 ml of acidic solution (breakthrough volume).
No samples containing herbicide residues at
detectable concentrations were found, so a recovery
test was carried out. The samples were spiked
four times at three concentrations (200, 400 and
600 ng per gram of plant) in order to have four
replicates for each spiked sample.