Determination of Partitioning Behaviour of Volatile Substances between Coated or Non-Coated Cardboard Samples and Air as a Basis for the Estimation of Migration from Packaging into Food

Partitioning of organic aroma compounds, wood derived volatile compounds, printing ink solvents or volatile environmental compounds between coated or non-coated cardboard and foodstuff is important for the migration behaviour of cardboard based food packaging and therefore for quality control of food packaging. The partitioning behaviour of all possible volatile organic compounds between cardboards and individual foodstuffs is difficult and too time consuming for being fully investigated. Therefore it may be more efficient and aim leading to determine these partition coefficients indirectly through experimental determination of the partitioning behaviour between cardboard samples and air. The aim of this investigation was to esthablish a method for the determination partition coefficients of volatile organic compounds between cardboard and air. For this purpose a headspace method was developed to measure the concentrations selected substances in air over the cardboard samples. The selected substances were a mixture of ten substances with differing volatility, polarity, molecular weight and chemical structure. This mixture was injected into empty headspace vials and vials containing cardboard samples. After equilibration an aliquot of each headspace was injected into a GC and detected by FID. Samples were spiked with different concentrations of volatile substances in the lower ppm range to determine the influence of the initial concentration of substances on partition coeffcients. By comparison of the headspace concentration of the substances with and without cardboard contact the partition coefficients between cardboard and air could be calculated. Partitioning kinetics was investigated to obtain the real equilibrium conditions at which the concentration of solutes did not increase further. Measurements were also carried out at different temperatures. Thus, the tendency of substances to be preferably in air or packaging at room temperature could be estimated by extrapolation of partition coefficient graphs for different temperatures.