migraDASH examples

1. mono layer

This is the simplest example to simulate a migration from a polymer plate into a food simulant or drinking water. The plate should consists of polyethylene (PE) and has a thickness of \(2\,\mathrm{mm}\) and a contact area of \(500\,\mathrm{cm}^2\). The second layer is a drinking water layer with a thickness of \(20\,\mathrm{mm} = 2\,\mathrm{cm}\), which results in a volume of \(500\,\mathrm{cm}^2 \cdot 2\,\mathrm{cm} = 1000\,\mathrm{cm}^3\). The contact time between the polymer plate and the drinking water should be 1 day at 23 °C. The PE includes the migrant trimethoxy vinyl silane (CAS 2768-02-7) with a initial mass fraction of \(100\,\frac{\mathrm{mg}}{\mathrm{kg}}\).

time/temperature cycles

The following cycle needs to be configured for the example:

	temperature		time		mode
C1		°C		d	migration

matrix

To configure the matrix, press first the -button in the layer 1 column, to get a second layer. Then enter the following value:

2 layers

matrix name
contact area	cm2

	layer 1	layer 2
layer name
thickness / volume	thickness mm volume mm3cm3dm3	thickness mm volume mm3
polymer/simulant	polyethylene (PE)	water

migrant

For the migrant section, enter the CAS number in the field name and click on the button migraBASE, left of migrant name. The molar mass and the \(\log P_{ow}\) are filled from the database.

1 migrant

no 1
migrant name

MTC / SML	mg/l
molar mass	g/mol
logPow$\log\,P_{ow}$

The migrant is at the beginning only in the polymer and not in the drinking water. So the value of \(100\,\frac{\mathrm{mg}}{\mathrm{kg}}\) is enterd for the first cycle w1 of the polymer layer and \(0\,\frac{\mathrm{mg}}{\mathrm{kg}}\) for the drinking water layer. For the diffusion coefficient of the polymer choose "Piringer". The diffusion coefficient will be estimated with the Piringer method. For the water layer choose "predefined", the predefined diffusion coefficient, in case of water \(0.0001\,\frac{\mathrm{cm}^2}{\mathrm{s}}\) is choosen ¹. For the partition coefficient between the drinking water and the polymer layer choose "\(\log P_{ow}\)" for the water layer. For the migration, there is no meaning to advise a partition coefficient to the first layer.

	layer 1 (polymer)	layer 2 (drinking water)
initial mass fraction	w1 value unit mg/kg	w1 value unit mg/kg
diffusion coefficient	compute Piringer	compute predefined
partition coefficient	compute logPow	compute logPow

Now you can press the submit-button to start the simulation.

2. repeated use

In case of migration test for contact materials to drinking water, there are several change cycles, i. e. the test water is refreshed after each cycle. In this example we will simulate the cold water test at 23 °C for 10 days for a polypropylene (PP) plate with a contact area of 500 cm² and a thickness of 3 mm. The duartion of the cycles are 1 day, 3 days, 3 days and 3 days.

time/temperature cycle

Fill the temperature 23 °C and the time 1 day for the first cycle, C1. Then press the copy button at the right side of the cycle. Change the time to 3 days in the second cycle C2. Copy this cycle two times, to finish the configuration of the cycles.

	temperature		time		mode
C1		°C		d	migration
C2		°C		d	migration
C3		°C		d	migration
C4		°C		d	migration

matrix

Configure the matrix for this example like in example 1, mono layer, but with PP instead of PE.

migrant

For the migrant, the configuration for the polymer layer is the same as for the example 1. The initial mass fraction values for the cycles w2, w3 and w4 are empty. This means the migration follows the law of diffusion.

For the water layer, the initial mass fraction is set to 0, for all four cycles w1, w2, w3, w4. This mean at the beginning of each cycle the mass fraction of the migrant in the water is set to 0, i. e. the water is refreshed. The rest of the configuration of the water layer is the same as in the example 1.

	layer 1 (polymer)	layer 2 (drinking water)
initial mass fraction	w1 value w2 value w3 value w4 value unit mg/kg	w1 value w2 value w2 value w2 value unit mg/kg
diffusion coefficient	compute Piringer	compute predefined
partition coefficient	compute logPow	compute logPow

3. multi layer

tbd.

4. set off layer

A two film consisting of two polymer layers is stored on a roll for 90 days at 23 °C. Afterwards the film is used as a packages of a cubic food with 1 dm³, and a migration modelling with 10 days at 40 °C should be modelled.

The example needs to two following cycles:

	temperature		time		mode
C1		°C		d	set_off
C2		°C		d	migration

The matrix of the example needs to be configured:

3 layers

matrix name
contact area	cm2

	layer 1	layer 2	layer 3
layer name
thickness / volume	thickness µmmmcm volume mm3cm3dm3m3	thickness µmmmcm volume mm3cm3dm3m3	thickness µmmmcm volume mm3cm3dm3m3
polymer/simulant	polyethylene (PE)	polypropylene(PP)	olive oil

The migrant has no contact to the rest of the matrix for the set-off cycle, but an initial value of '0' for the migration cycle.

1 migrant

no 1
migrant name

MTC / SML	mg/l
molar mass	g/mol
logPow$\log\,P_{ow}$
	layer 1 (polymer 1)	layer 2 (polymer 2)	layer 3 (food)
initial mass fraction	w1 value w2 keep unit mg/kg	w1 value w2 keep unit mg/kg	w1 no contact w2 value unit mg/kg
diffusion coefficient	compute Piringer	compute Piringer	compute predefined
partition coefficient	compute logPow	compute logPow	compute logPow

5. full immersion

tbd.

6. parts with complex geometry

tbd.

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1. Umweltbundesamt. Leitlinie zur mathematischen abschätzung der migration von einzelstoffen aus organischen materialien in das trinkwasser (modellierungsleitlinie). https://www.umweltbundesamt.de/sites/default/files/medien/419 /dokumente/modellierungsleitlinie.pdf. Stand 7. Oktober 2008. ↩