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