Correlation between Partition Coefficients Polymer/Food Simulant, KP,F, and Octanol/Water, Log POW ― a New Approach in support of Migration Modeling and Compliance Testing

An investigation on the migration of various migrants from low-density polyethylene (LDPE) into food simulants was undertaken to determine the correlation of partition coefficients between LDPE/food simulants, K P,F , and octanol/water, P OW . The migration tests were carried out using four simulants (10 %, 50 %, 95 % ethanol and olive oil) in contact with a LDPE film which was spiked with 15 compounds. These model migrants cover a wide range of potential migrants in plastics food packaging materials and can be characterized by octanol/water partition coefficients ranging from log P OW = 0.36 to 18.08. In all simulants a correlation of increasing log P OW with increasing log K P,F was found. Assuming a linear relationship, correlation coefficients (R) for 10 %, 50 %, 95 % ethanol and olive oil were 0.98, 0.65, 0.80 and 0.68, respectively. Using the correlation line as a calibration curve, log K P,F can be predicted from the log P OW values of the migrants for a given food simulant and, hence, migrating amounts can be estimated by migration modelling provided the migrant concentration in the polymer is known. This approach is a new estimation procedure to obtain K P,F values from easily accessible P OW values which can significantly reduce the efforts for compliance assessment by minimizing time and costs to be spent compared to carrying out an enormous number of specific migration test. Furthermore, this approach will support experimental migration testing since it provides a method to determine which simulant is appropriate for a given foodstuff.