The results obtained for bread samples evidenced how overnight
extraction with n-hexane often underestimates the total
mineral oil contamination present in the product (also when adding
anhydrous sodium sulphate to remove the water before extraction).
Particularly, it was found that after cooking, part of the
contamination present in the ingredients becomes less easily
extractable with n-hexane, but can be quantitatively extracted
with MAS. Fig. 3 displays an overlay of the LC–GC traces obtained
by applying MAS and overnight extraction with n-hexane in both
the spiked and the unspiked bread. Concerning the unspiked sample,
overnight extraction with hexane enabled extraction of 40% of
the MOSH extracted with MAS (1.0 mg kg1). This behaviour,
already observed in Melba toast (unpublished data), seems to indicate
that after cooking, part of the contamination remains firmly
enclosed into the product and cannot be easily extracted with nhexane
overnight, but can be completely extracted after MAS.
Differently from semolina pasta and bread, complete extraction
of mineral oil from the biscuit samples proved to be less difficult
and was achieved also when using overnight extraction. During
routine analysis a large number of biscuits with different fat content
was analysed in duplicate by applying both MAS and overnight
extraction with n-hexane (not all data are reported in this work). In
all cases the results obtained were comparable, indicating that
quantitative mineral oil extraction does not represent a difficult
task for this type of sample characterised by a high fat content (typically
ranging from 8 up to 25%) and a low moisture content (1–5%).
With respect to solvent extraction which co-extracts also the fat,
MAS allows the removal of fat before LC–GC analysis, with the