When processing high-fat content foods with non polar solvents,
mineral oils are co-extracted with the fat. Since the LC column
has a limited capacity to retain fat (20 mg), an additional
purification step aimed at reducing or eliminating fat (passage
through a bed of activated silica) is therefore required to reach
higher sensitivity. As an alternative, to eliminate high amounts of
fat before LC–GC analysis, the sample can be saponified. Traditional
saponification followed by unsaponifiable extraction has been previously
applied for determination of mineral oil or endogenous nalkanes
in different food samples (Castle, Kelly, & Gilbert, 1993;
Koprivniak, Procida, & Favretto, 1997). Traditional saponification
has the advantage that it can be applied to all food types, avoiding
the need to remove water before the extraction step, but it has the
disadvantage of being solvent- and time-consuming.