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- Practical Guide -
Page 78 of 153
Calculation of migration
Conditions: One side migration
estimation
time dependent migration (TDM)
TDM with effect of partitioning (E1)
Result: C
F,t
= 0.84 mg/kg < 6 mg/kg (SML).
Discussion of the result
The migration rate is significantly smaller than the SML value even if the additive is
considered to be soluble in the simulant (which is equivalent to a fat test). The other 7
additives from table 4.2.2 have higher molecular weights. It is therefore extremely
unlikely that one of these additives exceeds the respective SML value under the above
conditions of use. An overall migration test may be a good additional investigation for
confirmatory purposes.
Example 4:
A steam sterilizable container with a capacity of 500 ml and a cylindrical form, with a
maximum wall thickness of 2 mm is used for liquid or paste with fatty substances on the
surface, according to reference number 08.03 in the Directive 85/572/EEC. The container has
a PP label. The additives used are Irganox 1076 (0.06 %) and Irgafos 168 (0.1 %). This
information was obtained from the producer of the article.
Compliance testing of the above article according to Directive 97/48/EEC requires test
conditions of 2 h at 121 C 2 h followed by 10 days at 40 C using simulant D, olive oil.
Which informations can be obtained by mathematical modelling?
In the following two procedures are described:
Procedure 1 (two separate migration effects):
Modelling with the software:
...requires to provide the following informations:
1.
Information about the polymer
polymer thickness (0.2 cm)
polymer density
(0.91 g/cm
3
)
pre-defined polymer
PP
OK
2.
Information about the migrateable substance
migrateable substance from Synoptic
Document
search PM-Ref No (68320)
search
(Octadecyl-3-(3,5-di-tert-
butyl-4-hydroxyphenyl)propionate)
select
relative molecular weight (531)
OK
substance concentration in polymer (600 mg/kg)
calculation of diffusion
coefficient
migration process takes place at one (1) constant temperature level T
1
temperature T
1
(121 C)
estimation of diffusion coefficient with eq. (4)
calculate diffusion coefficient D
1
OK.
(in this way the migration effect attributed by the high temperature condition alone is
considered)