Optimisation of pressurised liquid extraction (PLE) for rapid and efficient extraction of superficial and total mineral oil contamination from dry foods

• MOSH and MOAH determination in dry food using PLE followed by on-line LC–GC.
• PLE for selective extraction of superficial contamination (mainly from packaging).
• PLE method for determining total contamination.
• Method performances and comparison with classical solvent extraction.
• Applications to pasta and rice samples.

Pressurised liquid extraction (PLE) represents a powerful technique which can be conveniently used for rapid extraction of mineral oil saturated (MOSH) and aromatic hydrocarbons (MOAH) from dry foods with a low fat content, such as semolina pasta, rice, and other cereals. Two different PLE methods, one for rapid determination of superficial contamination mainly from the packaging, the other for efficient extraction of total contamination from different sources, have been developed and optimised. The two methods presented good performance characteristics in terms of repeatability (relative standard deviation lower than 5%) and recoveries (higher than 95%). To show their potentiality, the two methods have been applied in combination on semolina pasta and rice packaged in direct contact with recycled cardboard. In the case of semolina pasta it was possible to discriminate between superficial contamination coming from the packaging, and pre-existing contamination (firmly enclosed into the matrix).