The effect of experimental variables on the efficiency of extraction
of PAH4 from food was investigated by extracting mussel samples,
which were selected as models for optimisation studies on the
basis of its representative protein, carbohydrate and fat content
(see the footnote in Table 4). Mussel samples (200 mg) containing
no PAH4 at detectable concentration levels were fortified with
10 lg kg1of each target PAH and analysed. It was checked that
the time of contact between the spike and the sample before its
extraction did not influence the recovery in the interval tested
(12–48 h), so 12 h was the time permitted for PAH-sample interaction
before analysis. The results were calculated as a mean of triplicate
measurements. Selection of optimal conditions for extraction
was based on the recoveries obtained for the target PAHs. The variable
investigated were the volume of extractant, sample amount
and time required to reach equilibrium conditions. The representativity
of the subsample selected for analysis was also investigated