Expected orders of magnitudes for partition coefficients

Three different approaches have been presented for estimating the partitioning of solutes between plastics and liquids. In the context of evaluating the output from these different approaches it is also useful to define the expected experimental ranges and limits for partition coefficients based on the solutes, plastic and contacting liquid phases involved. Table 4-9 shows approximate upper and lower limits for partition coefficients one may normally encounter in plastic/food systems based on the polarities of the solutes, plastics and foods. The table also gives approximate ranges of partition coefficient values for various solutes between typical food contact plastics and liquid phases. 

Polymer Very Polar Polyamide (PA) Ethylene vinyl alcohol (EVOH) 

To further illustrate the possible experimental ranges of partition coefficients, examples of experimentally determined partition coefficient ranges are given below. In Table 4-10 data for BHT partitioned between polypropylene and different food and food simulants at 40 °C and in Table 4-11 for d-limonene partitioned between LDPE and various foods and food simulants are shown. The partition coefficient values in these tables are representative examples of the ranges one can expect with polyolefins which are the most common food contact plastics. 

Liquid Phase d-Limonene liquid phase concentration ppm (w/v) Kp/l Reference 

Water with a sugar ester dispersant 1.8 84 Harita and Tanaka, 1989 

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