Résumé
This study validates the potential use of FTIR and Raman spectroscopy as suitable analytical methods for determining the diffusivity of a migrant in a plastic packaging material, one of the key points on safety assessment of food contact materials (FCM). Despite its relative low sensitivity, FTIR based analysis supplied data in the material on desorption of an additive (Uvitex OB) and sorption of a food constituent (olive oil) in a non-destructive and “in situ” mode. These data allowed to determine the diffusivity of Uvitex OB (8.0±2.5⋅10-14 m2s-1) and olive oil (6.9±3.4⋅10-14 m2s-1) in LLDPE. Raman cartography innovatively supplied the profile of additive concentration in the z-direction (thickness) of the FCM and confirmed that mass transfer in the system roughly followed a Fickean behaviour.