Fruit and vegetables (specified in Tables 2 and
3) were purchased in local shops and stalls.
Selected parts were cut into small pieces using a
knife and placed in glass tubes by using tweezers
to avoid losses of volatile compounds by warming
of samples during handling.
Dichloromethane (Merck, Darmstadt, Germany),
containing an internal standard (perdeuterooctane
at 5 pl #1-~), was added to the
tubes to extract MAHs from the fruit and vegetables.
A 0.5-1.5-ml volume of CH2CI 2 was used
for each tube, depending on the mass of the
material (0.5 ml of extraction solvent per gram of
fresh biological material). The tubes were closed
with screw-caps and PTFE tape and placed in a
slowly rotating drum for at least 6 h (the optimum
extraction time found to extract MAHs
from plant leaves [11]). The extracts were then
filtered (Millex-HV 0.45-/zm filter) and the filtrates
were collected in small bottles, which were
tightly closed again and stored in a freezer. The
residual material after filtration was dried in an
oven at 50-60°C for 7 days and weighed again to
determine the dry mass of the samples.