Validation of

Migration Modelling

► EU-Project SMT-CT98-7513

► EU Project

"Certified Reference Materials"

Content

► EU-Project SMT-CT98-7513

Estimation of Diffusion Coefficients

EU-Projekt

Evaluation of migration

models to be used

under directive

90/128/EEC

Partner No Name Institute Country

1 Piringer FABES DE Coordinator

2 Vergnaud Uni St. Etienne FR

3 Feigenbaum INRA FR

4 Castle MAFF UK

5 Rijk TNO NL

6 O’Brien PIRA UK

7 Franz FHG-ILV DE

8 Hamelton APME BE

9 Chaminade EuPC BE

10 Hadjiyianni BIT-FCA BE

11 Rebre ATOFINA FR

12 Brands/Lickly DOW Chemicals CH/USA

13 Schönhausen CIBA CH

14 Hinrichs COGNIS DE

15 Milana ISS I

16 Söderhjelm KCL SF

17 Begley FDA USA

Contract SMT4-CT98-7513

Scientific work

● systematic collection of diffusion data

- scientific literature

- food contact petitions (EFSA, FDA, BfR)

● experimental investigation of diffusion properties

- Pira International

● comparison between theory and experiment

RT

EA

eDD

0DP

Influence of:

polymeric material

(mobility)

migrant (size)

temperature

Estimation of diffusion coefficients (LDPE, RT)

-14

-13

-12

-11

-10

-9

-8

-7

-6

0 20 40 60 80 100 120

Mr2/3

log

DP

1

23

AP‘=11,5 , =0

Estimation of diffusion coefficients (LDPE, RT)

PE

-10,5

-10

-9,5

-9

-8,5

-8

-7,5

-7

150 200 250 300 350 400 450

Mr

log

Dp

log Dp ex LDPE

log Dp calc

AP‘=11,5, =0

Estimation of diffusion coefficients (LDPE, 40°C)

PP

-10,5

-10

-9,5

-9

-8,5

-8

-7,5

-7

150 200 250 300 350 400 450

Mr

log

Dp

log Dp ex PP

log Dp calc

AP‘=13,1, =1577

Estimation of diffusion coefficients (PP, RT)

DP - Diffusion coefficient (D0 = 104 cm²/s)

AP= AP‘-/T - material specific constant

( - material specific temperature constant)

Mr - relative molar mass of migrant in Dalton

T - temperature in K

EA - reference activation energy

(= R·10454 = 86,9 kJ, R = 8,314 J/K·mol)

TR

RMMADD rrPP

10454003.01351.0exp

3/2

0

Diffusion modelling

0

5

10

15

20

25

30

35

40

4 5 6 7 8 9 10 11 12 13 14 15 16

AP'-valueno. values: 134

mean value AP‘ = 11,29

standard deviation = 1,76

confidence interval (95%) = 7,85 - 14,74 ( = MW ± 1,96*STABW)

AP‘* = 14,5

Upper limit AP*-values

real diffusions coefficient: DP AP

„upper limit“ diffusion coefficient : DP* AP*

- an „upper limit“ diffusions coefficient DP* gives a „worst

case“ migration estimation

Legal requirements for AP-values

Polymer AP´ T [°C] cP,0 [%]

LDPE 11.5 0 < 80 < 1

LLDPE 11.5 0 < 100 < 1

HDPE 14.5 1577 < 90 < 1

PP(homo) 13.1 1557 < 120 < 1

PP(random) 13.1 1557 < 120 < 1

PP(rubber) 11.5 0 < 100 < 1

FOOD CONTACT MATERIALS

PRACTICAL GUIDE

“A PRACTICAL GUIDE FOR USERS OF EUROPEAN DIRECTIVES ”

Upper limit AP*-values (polyolefines)

Polymer AP´ T [°C] cP,0 [%]

PS 0 0 < 70 < 1

HIPS 1 0 < 70 < 1

PET 6 1577 < 175 < 1

PEN 5 1557 < 175 < 1

PA 6,6 2 0 < 100 < 1

FOOD CONTACT MATERIALS

PRACTICAL GUIDE

“A PRACTICAL GUIDE FOR USERS OF EUROPEAN DIRECTIVES ”

Upper limit AP*-values (non-polyolefines)

Table 6 Statistical validation of AP’-values for migration modelling under ’worst case’

conditions

Polymer

AP’

s

AP’(max)

AP’(min)

N

t

AP’*

LDPE 10.0 1.0 11 7.0 27 1.7 11.7 0

HDPE 10.0 1.9 12.6 5.0 49 1.68 13.2 1577

PP 9.4 1.8 12.9 6.2 53 1.68 12.4 1577

PET 2.2 2.5 7.2 -4.3 58 1.67 6.35 1577

PEN -0.34 2.4 3.8 -5.5 38 1.7 3.7 1577

PS -2.8 1.25 0.0 -6.5 32 1.7 -0.7 0

HIPS -2.7 1.67 0 -6.2 33 1.7 0.1 0

PA (6,6) -1.54 2.0 2.3 -7.7 31 1.7 1.9 0

Other Polymers (EU-Project Migration Modeling)

AP= AP'-/T Food Additives and Contaminants, 2005; 22(1): 73–90

Diffusion properties of different

polymers can be compared

based on their AP-value,

i.e. mobility of the polymer

► high AP-values account for high

mobility of the polymer (flexible

polymers) and high diffusion

coefficients respectively

► low AP-values account for low

mobility of the polymer (rigid

polymers) and low diffusion

coefficients respectively

Migration process (Mass transfer)

DP AP[cm²/s]

gases ~ 10-1

liquids ~ 10-5 20

viscous liquids ~ 10-6 18

soft PVC ~ 10-7 16

Polymere T > TgLDPE ~ 10-9 11

HDPE ~ 10-10 9

PP ~ 10-11 7

Polymere T < TgPA ~ 10-13 2

PS ~ 10-14 0

PET ~ 10-15 -2

rigid PVC ~ 10-16 -4(Tg - glas temperature)

Diffusion coefficients (at T=20°C, Mr=300 g/mol)

► EU Project "Certified

Reference Materials"

PARTNERS :

Fraunhofer Gesellschaft D (IVV)

Pira International UK (PIRA)

MAFF-CSL UK (CSL)

FABES Forschungs-GmbH D (FABES)

BIT-FCA B/EU (FCA)

Certified Reference Materials for the specific migration testing

of plastics for food packaging

PROJECT G6RD-CT-2000-00411

List of candidate materials

No Polymer PM/REF

No

Additive/Monomer/Test Substance Brand name e.g. SML

(mg/kg)

proposed

level %

MW Proposed

film/plaque

thickness

(range µm)

thickness

of

materials

(µm)

Form Production

mode

Commercial

availability/

possiblity of

production

T max

°C

Simulant

(migration

test)

Time/Temp

(migration

test)

1 LDPE 68320 Benzenepropanoic acid 3,5-bis(1,1-

dimethylethyl)-4-hydroxy- octadecyl ester

Irganox 1076 6 0,15 531 300-500 300 Film flat film Ind., tailor

made

Polymer matrix : HDPE

HDPE

type 1: = 0,948

d = 1043 µm

migrants: Irganox 1076 (antioxidant)

Irgafos 168 (antioxidant)

type 2: = 0,933

d = 356 µm

migrants: Chimassorb 81 (UV-absorber)

Uvitex OB (optical brightener)

O OH

O

CH3

CH3

CH3

CH3

N

O N

O

S

CH3

CH3

CH3

P

O

O

O

CH3

CH3

CH3CH3

CH3

CH3

CH3

CH3

CH3

CH3

CH3

CH3

CH3CH3

CH3

CH3 CH3

CH3

Structure of migrants

CH3

CH3

CH3CH3

CH3

CH3

OOCH3

OH

Uvitex

OB

Irgafos 168

Irganox 1076

Chimassorb

81

Experimental considerations

migration cell (one sided)

area, A = 48 cm²

volume, V = 10 ml

Migration of Irganox 1076 into ethanol 95%

0

500

1000

1500

2000

2500

3000

3500

4000

0 2 4 6 8 10 12

time [days]

co

ncen

trati

on

[µg

/dm

²]

40°C (exp.A)

40°C (exp.B)

60°C (exp.A)

60°C (exp.B)

80°C (exp.A)

80°C (exp.B)

CH3

CH3

CH3CH3

CH3

CH3

OOCH3

OH

Migration of Irgafos 168 into ethanol 95%

0

100

200

300

400

500

600

700

800

0 2 4 6 8 10 12

time [days]

co

ncen

trati

on

[µg

/dm

²]

40°C (exp.A)

40°C (exp.B)

60°C (exp.A)

60°C (exp.B)

80°C (exp.A)

80°C (exp.B)

P

O

O

O

CH3

CH3

CH3CH3

CH3

CH3

CH3

CH3

CH3

CH3

CH3

CH3

CH3CH3

CH3

CH3 CH3

CH3

Migration of Chimassorb 81 into ethanol 95%

0

500

1000

1500

2000

2500

3000

3500

0 2 4 6 8 10 12

time [days]

co

ncen

trati

on

[µg

/dm

²]

40°C (exp.A)

40°C (exp.B)

60°C (exp.A)

60°C (exp.B)

80°C (exp.A)

80°C (exp.B)

O OH

O

CH3

Migration of Uvitex OB into ethanol 95%

0

200

400

600

800

1000

1200

0 2 4 6 8 10 12

time [days]

co

ncen

trati

on

[µg

/dm

²]

40°C (exp.A)

40°C (exp.B)

60°C (exp.A)

60°C (exp.B)

80°C (exp.A)

80°C (exp.B)

CH3

CH3

CH3

N

O N

O

S

CH3

CH3

CH3

- the migration process follows the laws

of diffusion

- the liquid is a well mixed

- data set: dP [µm]

P [g/cm³]

VF [cm³]

F [g/cm³]

A [g/cm³]

t [days]

T [°C]food

simulant

Migrant

HDPE

DP

KP,FMigration

experiment

Migration modelling

Fundamental physical constants

Fitting procedure by variation of the diffusion

coefficient, DP and the partition coefficient, KP,F

12

2

220,

,exp

1

121

1 n P

nP

n

PPP

tL

d

qtD

qdc

A

m

LP

PL

K

VV

,

/

0

500

1000

1500

2000

2500

3000

3500

4000

0 2 4 6 8 10 12

time [days]

co

ncen

trati

on

[µg

/dm

²]

40°C (exp.A)

40°C (exp.B)

40°C (calc.)

60°C (exp.A)

60°C (exp.B)

60°C (calc.)

80°C (exp.A)

80°C (exp.B)

80°C (calc.)

Modelling of Irganox 1076 migration

CH3

CH3

CH3CH3

CH3

CH3

OOCH3

OHcP,0 = 850 ppm (8404 µg/dm²)

Modelling of Irgafos 168 migration

0

100

200

300

400

500

600

700

800

0 2 4 6 8 10 12

time [days]

co

ncen

trati

on

[µg

/dm

²]

40°C (exp.A)

40°C (exp.B)

40°C (calc.)

60°C (exp.A)

60°C (exp.B)

60°C (calc.)

80°C (exp.A)

80°C (exp.B)

80°C (calc.)

P

O

O

O

CH3

CH3

CH3CH3

CH3

CH3

CH3

CH3

CH3

CH3

CH3

CH3

CH3CH3

CH3

CH3 CH3

CH3

cP,0 = 517 ppm (5112 µg/dm²)

Modelling of Chimassorb 81 migration

0

500

1000

1500

2000

2500

3000

3500

0 2 4 6 8 10 12

time [days]

co

ncen

trati

on

[µg

/dm

²]

40°C (exp.A)

40°C (exp.B)

40°C (calc.)

60°C (exp.A)

60°C (exp.B)

60°C (calc.)

80°C (exp.A)

80°C (exp.B)

80°C (calc.)

O OH

O

CH3

cP,0 = 935 ppm (3106 µg/dm²)

Modelling of Uvitex OB migration

0

200

400

600

800

1000

1200

0 2 4 6 8 10 12

time [days]

co

ncen

trati

on

[µg

/dm

²]

40°C (exp.A)

40°C (exp.B)

40°C (calc.)

60°C (exp.A)

60°C (exp.B)

60°C (calc.)

80°C (exp.A)

80°C (exp.B)

80°C (calc.)

CH3

CH3

CH3

N

O N

O

S

CH3

CH3

CH3

cP,0 = 471 ppm (1564 µg/dm²)

Migrant

40°C 60°C 80°C 40°C 60°C 80°C

Irganox 1076 3,9E-11 4,3E-10 3,3E-09 15,0 3,0 0,1

Irgafos 168 2,1E-12 7,2E-11 4,5E-10 80,0 50,0 3,0

Chmiassorb 81 5,0E-10 2,7E-09 1,9E-08 0,1 0,1 0,1

Uvitex OB 4,5E-11 4,5E-10 4,7E-09 1,0 1,0 0,1

Diff.coef Part.coeff

Fundamental physical constants

Fitting procedure by variation of the diffusion coefficient, DPand the partition coefficient, KP,F gives for the best fit:

DP - Diffusion coefficient (D0 = 104 cm²/s)

AP= AP‘-/T - material specific constant

( - material specific temperature constant)

Mr - relative molar mass of migrant in Dalton

T - temperature in K

EA - reference activation energy

(= R·10454 = 86,9 kJ, R = 8,314 J/K·mol)

TR

RMMADD rrPP

10454003.01351.0exp

3/2

0

Diffusion modelling

Migrant

40°C 60°C 80°C 40°C 60°C 80°C

Irganox 1076 12,5 12,6 12,6 1577 1577 1577

Irgafos 168 10,5 11,7 11,5 1577 1577 1577

Chmiassorb 81 13,2 12,6 12,5 1577 1577 1577

Uvitex OB 11,8 11,8 12,1 1577 1577 1577

Ap'

Polymer specific constant, AP'

AP’

mean value 12,1 1577

standard deviation 0,7 0

upper limit values *) 13,5 1577

The influence of the migrant structure on the diffusion

coefficient is within the standard deviation of ± 10%.

0

5

10

15

20

25

30

35

40

4 5 6 7 8 9 10 11 12 13 14 15 16

AP'-value

no. values: 134

mean value AP‘ = 11,29

standard deviation = 1,76

confidence interval (95%) = 7,85 - 14,74

( = MW ± 1,96*STABW)

AP‘* = 14,5

Upper limit AP-values