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- Practical Guide -
Page 75 of 153
Example 1:
A film of LDPE with a thickness of 100 Ám is used for sandwiches with fatty substances on
the surface. This kind of food is stored at 4░ C for maximum 7 days. It is known that the film
contains Irganox 1076 and Irgafos 168 as additives.
What information can be obtained about the specific migration of the two additives by
mathemical modelling?
Modelling with the software
... requires to provide the following informations:
1.
Information about the polymer
«
polymer thickness (0.01 cm)
«
polymer density
(0.945 g/cm
3
)
«
pre-defined polymer
«
LDPE
«
OK
(the density value 0.945 is the highest density for LDPE and gives a worst case for the
amount of migrant per volume of PO. The density ranges for each class of polymer are
shown when the pre-defined polymer is selected).
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 (5000 mg/kg)
«
calculation of diffusion
coefficient
«
migration process takes place at one (1) constant temperature level T
1
«
temperature T
1
(5░ C)
«
estimation of the diffusion coefficient with eq. (4)
«
calculate diffusion coefficient D
1
«
OK.
(The above initial concentration of 5000 mg/kg can be assumed as an upper limit for all
the additives from table 4.2.1 for PO. From a practical and economical standpoint this
value is exaggerated.)
3.
Information about the foodstuff or food simulant
«
food simulant
«
D olive oil
«
OK.
Information about the packaging
«
Conventional EEC Packing
«
yes
«
OK.
Information about the contact between material and food
«
T
1
«
solubility of
migrant
«
soluble
«
OK
«
user defined contact data
«
days (10)
«
OK.
Calculation of migration:
Conditions: One side migration
«
estimation
«
time dependent migration (TDM)
«
TDM
with effect of partitioning (E1). (Remark that TDM with effect of partitioning is the
selection that is usually is the right one for these situation of modelling, This is useful
because there are several options in the software)
Result: m
F,t
/A = 2.8 mg/dm
2
.
Discussion of the result:
Save the above result of modelling in a corresponding file, denoted for example as Ex1.