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Page 1: Specific migration testing with alternative fatty food simulants

This article was downloaded by: [Linnaeus University]On: 15 October 2014, At: 14:04Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: MortimerHouse, 37-41 Mortimer Street, London W1T 3JH, UK

Food Additives & ContaminantsPublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/tfac19

Specific migration testing with alternative fattyfood simulantsIan Cooper a , Anne Goodson a & Anthony O'Brien aa Pira International , Randalls Road, Leatherhead, Surrey, KT22 7RU, UKPublished online: 10 Jan 2009.

To cite this article: Ian Cooper , Anne Goodson & Anthony O'Brien (1998) Specific migration testing with alternativefatty food simulants, Food Additives & Contaminants, 15:1, 72-78, DOI: 10.1080/02652039809374600

To link to this article: http://dx.doi.org/10.1080/02652039809374600

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Page 2: Specific migration testing with alternative fatty food simulants

Food Additives and Contaminants, 1998, Vol. 15, No. 1, 72-78

Specific migration testing with alternative fattyfood simulants*

Ian Cooper, Anne Goodson and Anthony O'BrienPira International, Randalls Road, Leatherhead, Surrey KT22 7RU,UK

Many additives used in plastics materials and articlesintended for food contact are expected to be assignedspecific migration limits (SMLs) in a future amend-ment to EC Directive 90/1128/EEC. In order to demon-strate compliance with these restrictions, specificmigration tests will need to be performed on the finishedplastics packaging using foods or the appropriate ECfood simulants. Owing to the involatile and lipophilicnature of many of these additives, their analysis in theconventional fatty food simulant, olive oil, presentstechnical difficulties. One way of overcoming thesedifficulties would be to use a simple solvent alternativeto olive oil as has been proposed for overall migrationtesting. The objective of this work is to compare specificmigration data obtained using olive oil with alternativefat simulants iso-octane and 95% ethanol, to find out ifsimilar results are obtained and identify the mostappropriate alternative simulant to use for futuretesting. Good agreement with the olive oil migrationdata was obtained using 95% ethanol (equivalentexposure conditions) for both of the additives studiedin polyolefins. For the polystyrene materials studied it isunlikely that the SMLs for the two additives would beexceeded, and in these cases iso-octane (1.5 h at 60° C)could be used as a rapid 'alternative test'.

Keywords: additive migration, alternative simulants,food contact, specific migration

* Paper presented as a Poster at the ILSI Europe, InternationalSymposium 'Food Packaging—Ensuring the Safety and Quality ofFoods' held in Budapest (Hungary) from Sept. 11-13th 1996.

Introduction

EC Directive 90/128/EEC (EEC 1990) and amend-ments covering plastics materials and articles in-tended to come into contact with foods contains alist of permitted monomers, some of which arerestricted, and an incomplete list of additives whichare not subject to a restriction. This directive isexpected to be amended further to include thoseplastics additives which will be assigned restrictions,probably in the form of specific migration limits.

In order to demonstrate compliance with these re-strictions, specific migration tests will need to be per-formed on the finished plastics packaging using foodsor the appropriate EC food simulants. Measurementof many of these additives in the aqueous foodsimulants water, 3% acetic acid and 15% ethanol isusually straightforward, but their determination inthe EC conventional fatty food simulant olive oilpresents a number of difficulties, namely:

• many of the additives are lipophilic and difficult toisolate from olive oil

• olive oil is a complex and variable natural productcontaining many potential interferences with theanalysis

• olive oil is of low volatility and cannot be usefullyconcentrated by evaporation

• the additives are also generally of low volatility,precluding the application of headspace analysis

• few analytical methods are currently available

One way of overcoming these difficulties would be touse a simple solvent alternative to olive oil as has beenproposed for overall migration testing (De Kruijf andRijk 1988, 1994). Use of'volatile extraction solvents',such as 95% ethanol for polyolefins, is also permittedby the Food and Drugs Administration (FDA) forindirect food additive petitions (FDA 1995). A com-prehensive review by Baner et al. (1992) describesresearch already conducted in this field.

0265-203X/98 $12.00 © 1998 Taylor & Francis Ltd

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Specific migration testing with alternative fatty food simulants 73

In the 'Practical Guide Nl ' (EEC 1993) whichprovides guidance to workers generating migrationdata on new substances for submission to the Scien-tific Committee for Food (SCF), iso-octane and 95%ethanol with appropriate exposure conditions arelisted as alternatives to olive oil in cases wheremigration testing using olive oil or the other fatsimulants poses insurmountable difficulties. Morerecently, the European Commission, in a draft secondamendment to Directive 82/711/EEC (EEC 1996), haslisted an extended range of 'substitute' and 'alter-native tests'. A 'substitute' test can be used when thetest with conventional fatty food simulants is notfeasible due to technical reasons associated with theanalysis. 'Alternative' tests may be used where valuesobtained are higher or equivalent to values obtainedwith the fatty food simulant. Although these simu-lants have mostly been evaluated as alternatives toolive oil for overall migration testing they are alsobeing proposed as being suitable for specific migra-tion testing and intructions are given in the draftamendment to conduct 'substitute' tests with all threeof the suggested alternatives (95% ethanol, iso-octaneand Tenax) and take the highest value obtained.

The purpose of this work is to compare the resultsobtained using olive oil in specific migration tests onplastics additives with those obtained using thosealternative simulant/equivalent exposure combina-tions proposed in the 'Practical Guide' and draftsecond amendment to Directive 82/71 I/EEC, toestablish:

• if analysis of the selected additives is facilitated byuse of the alternative simulant;

• if the results obtained are comparable with olive oilresults; and

• the most appropriate alternative simulant to use ineach case

Experimental

The two additives selected for this study were:

• Octadecyl 3-(3,5-di-ter?-butyl-4-hydroxyphenyl)-propionate (Irganox 1076, used as an antioxidant),PM/REF 68320. Expected SML= 6mg/kg.

• Di(2-ethylhexyl)adipate (DEHA), used as a plasti-cizer and carrier for colorants, PM/REF No.31920. Expected SML= 18mg/kg.

Polymer plaques of thickness 2 mm, containing thesetwo additives, were obtained from a separate butparallel study to investigate and correlate additiveconcentration in polymers {Cp) against migration ofthe additives into food simulants (Cf). Measuredvalues for Cp and Cf (in olive oil) were also availablefrom the other study. The experimental details of themeasurement of these additives in the polymer aretherefore not repeated in this paper as they aredescribed in detail in another paper published in thisjournal covering the Proceedings of the ILSI Pack-aging Symposium (O'Brien et al. 1997). In the studyreported here these same polymer samples weresubjected to migration tests using the proposed 'alter-native' fat simulants (iso-octane and 95% ethanol)under various equivalent exposure conditions given inthe literature or EC/FDA documents. In addition,Tenax, which has been proposed as a high tempera-ture alternative, has also investigated in a limitednumber of experiments.

Migration tests with the alternative simulants wereperformed in triplicate, or duplicate, by totally im-mersing two 6-6 x 3 cm test pieces in 66 ml of simu-lant contained in a glass-stoppered tube. The sameratio was used in migration tests conducted with oliveoil. As the polymer test pieces were relatively thick,and in all cases less than 50% of the total additivepresent was found to migrate, the surface area of bothsides of the test specimens was taken into account soresults were divided by a factor of 2 to convert to theEC conventional exposure ratio of 6 dm2 of packa-ging to 1 kg (1) of food. Most of the tests wereperformed in an incubator or oven, except for the121°C test with 95% ethanol and one of the 121°Colive oil tests, which were performed in a 100 mlSchott borosilicate bottle using an autoclave. In thecase of testing with Tenax (poly(2,6-diphenyl-/?-phe-nylene oxide)), the plaques were cut to size,6 cm x 6-6 cm, separately placed into Petri dishesand 1-6 g of Tenax was spread evenly on top. Follow-ing the exposure (2 h/121°C) the Tenax was extractedusing diethyl ether for determination of the Irganox1076 (see below). It was found to be necessary topurify the Tenax prior to the exposure by Soxhletextraction using diethyl ether for 16 h.

Measurements of the stability of Irganox 1076 andDEHA were made in the alternative simulants underselected exposure conditions, by storing a solution ofthe additive (at the SML level) in the blank simulantin parallel with the migration tests with analysis usingthe same procedure as for the samples. Measurements

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74 /. Cooper et al.

of recovery were conducted in selected cases byexposing plaques which were identical in all respectsto the test specimens, except they contained noadditive, to the same test conditions and alternativesimulants and spiking the final test solution with theadditive at approximately 6 mg/kg.

DEHA was determined in olive oil by dilution of 0-5 gof the oil in 25 ml of rc-heptane after addition of theinternal standard (2 ml of dinonyl adipate, lOug/mlin heptane). The solution was then injected for hightemperature GC-FID analysis using the conditionsdescribed below. Standards were prepared by makingknown additions of DEHA to blank olive oil andfollowing exactly the same procedure as for thesamples. A detection limit of 10 mg/kg in olive oilwas achieved, equating to about 5 mg/kg when con-verted to the conventional EC ratio of 6 dm2/kg. Themethod performance was estimated by analysis of sixaliquots of a spiked test olive oil. For the determina-tion of DEHA in the alternative simulants, 95%ethanol and iso-octane, 1 ml of the internal standard,dissolved in the appropriate simultant, was added to10 ml of the test simulant and the solution injected forGC analysis (see below). Quantitative results wereobtained by comparison against standards preparedsimilarly in the same blank simulant. A much betterdetection limit could be achieved (~0-2 mg/kg) com-pared with the measurement in olive oil and thecolumn did not require heating to 360°C to removeresidual olive oil. Quantitative values were obtainedby comparison against standards prepared in theappropriate blank alternative simulant.

Irganox 1076 was determined in olive oil by diluting2 ±001 g of oil to 10 ml with acetone, then injectionof this solution for reverse phase HPLC analysis withfluorescence detection using the conditions givenbelow. Standards were prepared similarly by makingadditions of Irganox 1076 in acetone to 2g ofblank olive oil and dilution to 10 ml with acetone.For determination of Irganox 1076 in 95% ethanol,the solution was directly injected and comparedagainst standards prepared in blank 95% ethanol.In measurement of Irganox 1076 in iso-octane,however, to render the solution compatible withreverse phase HPLC, the solvent (5 ml) wasevaporated to dryness under nitrogen and the residuere-dissolved in 5 ml of acetonitrile/THF 80/20. Fordetermination of Irganox 1076 in Tenax, the anti-oxidant was extracted by shaking at room tempera-ture for 10 s with 3 x 30 ml portions of diethyl ether.The combined extracts were filtered, evaporated todryness under nitrogen and the residue was dissolvedin acetonitrile/THF 80/20 and injected for HPLCanalysis. The recovery of this procedure was esti-mated by spiking Tenax with Irganox 1076 at about6 mg/kg prior to heating at 121°C/2h. A meanrecovery of 88% was obtained.

HPLC conditions for determination of Irganox1076

GC conditions for determination of DEHA

Column

Temperature

Carrier gasDetectorInjectorRetention time

12 m x 0-32 mm BPX5 0-25 um film(SGE)

100°C hold 1 min-> 210°C at 30°C/min-+ 240°C at 10°C/min-» 360°Chold 10 minHelium 50 kPaFID 370°CCold on-columnDEHA 8-6 min, dinonyl adipate

8-9 min

Column

Mobile phase

Solventprogramme

Flow rateDetector

Injection loopRetention time

Hypersil ODS C18 250x4-6 mm5 um particles

Solvent A propan-2-ol 25%, aceto-nitrile 75%

Solvent B 50% tetrahydrofuran,50% acetonitrile

Solvent A hold 8 min—> Solvent B in 1 min, hold for

5 min (column clean-up)—> Solvent A (5 min column regen-

eration)Note: column clean-up only re-quired for olive oil analysis1-5 ml/minFluorescence, excitation wave-

length 282 nm, emission 308 nm20 ulIrganox 1076, 7-6 min

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Page 5: Specific migration testing with alternative fatty food simulants

Specific migration testing with alternative fatty food simulants 75

Results and discussion

All results have been corrected, if necessary, toconvert to the conventional EC ratio of 6 dm2 ofpackaging for 1 kg (1) of food. The results for Irganox1076 are given in tables 1 and 2, with table 2representing results obtained under more stringenttest conditions. The results for DEHA are given intable 3. No corrections have been made to the resultsfor the measured stability of the substances in thesimulants. The results for Tenax have been correctedfor recovery; in all other cases no corrections havebeen made, as the determined recoveries were allbetween 91 and 101%. In all cases, except for Tenaxand Irganox 1076 in iso-octane, the measurementsinvolved direct analysis, or simple dilution, and thestandards were prepared to match the sample. Goodagreement was obtained betwen replicates, generallywithin ±10% RSD. Recovery experiments conductedby exposing 'blank' HDPE and PP plaques to iso-octane (2 days/20°C) gave mean recoveries of 98 and101%, respectively, on spiking the final test solutionswith 6mg/kg Irganox 1076. Similar experiments with95% ethanol (2h/121°C) gave recoveries of 91% and92% for HDPE and PP, respectively, for Irganox1076. The recovery of the method for determinationof DEHA in olive oil was found to be 97%. It is clearthat similar migration results have been obtained forpolyolefins with both additives using 95% ethanoland olive oil when tested under identical exposure

conditions, although there is significant overestima-tion at higher temperatures for Irganox 1076. Toestablish if using an autoclave could cause this over-estimation a second test was performed at 121 °C witholive oil, but this time using an autoclave instead ofan oven. A significant increase in the migration valuewas observed, probably owing to the additionalexposure time allowed before the autoclave could besafely opened. In this study, a mean 'stability recov-ery' of 87% was found for Irganox 1076 in olive oil at121°C for 2h (autoclave) which was similar to therecovery obtained with 95% ethanol (86%) under thesame conditions. In the parallel study (O'Brien et al.1997) Irganox 1076 was found to be less stable (72%recovery) although in this case the exposure wasconducted in an oven. The stability could well varyaccording to how the exposure is conducted, particu-larly with antioxidants such as Irganox 1076 whichare susceptible to oxidation. It is not considered validto directly correct for this loss as the additive diffusesgradually into the simulant during the exposure,whereas in the stability experiments the additive isexposed to the simulant for the full time.

Analysis of both additives in 95% ethanol involvesdirect injection of the simulants and is significantlyeasier and less prone to interferences compared withthe procedures used with olive oil. The 95% ethanol,121cC/2 h tests were all performed using an autoclave.However, when conducting these tests sufficient timeshould be allowed for cooling the Schott bottles prior

Table 1. Migration data for Irganox 1076 (10 days\40° C).

Level in polymer (%)

Olive oil, 10 days,40° C

Iso-octane, 2 days/20°C

95% Ethanol, 10 days/40°C

HDPE

005

2-2

0-40-40-3

mean = 0-40-90-80-7

mean = 0-8

HDPE

0-25

PP

005

Polymer type

PP

0-25

Migration mg/kg (replicate and mean

6-46-25-9

mean = 6-23-83-73-7

mean = 3-74-94-95-3

mean = 50

1-11-51-6

mean =3-43-53-5

mean =

4-24-24.4

1-4 mean = 4-315-415-314-7

3-5 mean=15-l4-64-84-8

mean = 4-7

HIPS

011

values)

<0-7<0-7<0-7

mean = <0-76-67-67-0

mean = 7-1100-910

mean = 1-0

ABS

0-36

0-60-60-5

mean = 0-63-23-23-0

mean = 3-1

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76 /. Cooper et al.

Table 2. Migration data for Irganox 1076 (more stringent test conditions).

Level in polymer (%)

Olive oil, 2 h/ 121°C(autoclave)

Olive oil, 2 h/121°C

Iso-octane, 2-5 h/60°C

95% Ethanol, 4-5 h/60°C

95% Ethanol, 2 h/121°C

Tenax, 2h/121°C

Olive oil, 2 h/100°C

95% Ethanol, 3-5 h/60°C

Iso-octane, l-5h/60°C

HDPE

005

11-311-212-7

mean= 11-82-72-82-4

mean = 2-60-50-50-5

mean = 0-5

HDPE

0-25

PP

005

Polymer type

PP

0-25

Migration mg/kg (replicate and mean

68-069-6

mean = 68-857-354-5

mean = 55-9

13-113-210-7

mean= 12-32-93-32-6

mean = 2-976-372-972-4

mean = 73-81-51-50 1

mean = 1-0

10011-210-9

mean = :6-76-47-1

mean =

54-448-9

mean = 51-741-141-1

mean = 41-l10-7

30-427-531-3

6-7 mean = 29-72-92-72-5

mean = 2-767-959-4

mean = 63-6

1-31-41-3

mean= 1-3

HIPS

011

values)

2-82-92-7

mean = 2-80-40-30-3

mean = 0-33-32-73-0

mean = 3-0

ABS

0-36

0-60-60-7

mean = 0-612-713-413-7

mean =13-31-61-41-4

mean= 1-5

to their removal from the autoclave owing to the highpressures developed. Although there is a potentialhazard in exposing closed bottles containing 95%ethanol to temperatures of 121°C, there should beminimal risk using Schott bottles in a modern auto-clave with a safety lock.

Tenax was found to grossly underestimate migrationof Irganox 1076 and is likely to be a totally unsuitablealternative to olive oil for specific migration testing of

low volatility substances, such as additives. This isperhaps not a surprising finding as Irganox 1076 is alow volatility compound and the mechanism for itstransfer to Tenax is expected to be mainly through thevapour phase.

Shorter exposure times at 60°C with both iso-octaneand 95% ethanol were found to underestimate migra-tion compared with olive oil for polyolefins butgood agreement was obtained with the polystyrene

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Page 7: Specific migration testing with alternative fatty food simulants

Specific migration testing with alternative fatty food simulants

Table 3. Migration data for DEHA.

Polymer type

77

HDPE HDPE PP PP

Level in polymer (%)

Olive oil, 10 days/40°C

Iso-octane, 2 days/20°C

95% Ethanol, 10 days/40°C

<005 0-42 <005 0-34

Migration mg/kg (mean values)

HIPS

105

5-45-84-1

mean = 5-10-60-404

mean = 0-5

0-3<0-3

0-5mean = 0 4

53-553-956-7

mean = 54-739448-145-246-141-9

mean = 44-148-647-342-6

mean = 46-2

<5<5<5

mean = <50-30-30-5

mean = 0 4

0-60-30 4

mean = 0 4

33-134-233-9

mean = 33-726-526424-3

mean = 25-7

33-233-034-2

mean = 33-5

<5<5<5

mean = <5302-93-1

mean = 3-0

141-51-5

mean= 1-5

materials using iso-octane at 60°C for 1-5 h, com-pared with olive oil at 100°C for 2 h.

Irganox 1076 was found to be relatively stable in bothalternative simulants with recoveries obtained of 95%and 86% at 4-5 h/60°C and 2h/121°C, respectively(95% ethanol) and 98% and 103% at 2-5 h/60°C and2 days/20°C, respectively, in iso-octane. DEHA wasalso found to be reasonably stable giving 93-5%recovery in 95% ethanol (10 days/40°C) and 98-9%recovery in iso-octane (2 days/20°C).

Conclusions

It is clear that with the alternative simulants used inthis study it is not possible to specify one which givesequivalent results to olive oil for all polymers. A moreproductive approach could be to specify a suitablealternative simulant for each polymer type providedno solubility or compatibility problems occur.

For the polyolefin samples, specific migration valuesobtained for both substances with 95% ethanol, usingthe same exposure conditions, were found to givegood agreement with values obtained using olive oil.This is in line with the FDA recommendations. For

the polystyrene samples, reasonable agreement wasobtained with the olive oil results using iso-octanewith the 'equivalent' exposures suggested in the ECdocuments (EEC 1996), although iso-octane gives anoverestimate at 10 days/40°C for HIPS. For thepolystyrene materials studied it is unlikely that theSMLs for the two additives would be exceeded, and inthese cases iso-octane (1-5 h at 60°C) could be used asa rapid compliance test.

For the two polymers studied, and using the sameexposure conditions, Tenax was found to grosslyunderestimate the Irganox 1076 specific migrationvalues and is therefore unsuitable for the applicationsstudied.

In the experiments described, analysis of the twosubstances in both iso-octane and 95% ethanol wasfound to be significantly easier compared with theirdetermination in olive oil.

Acknowledgements

The authors thank the industry sponsors of the PiraInternational 'Migration Project' for provision of

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78 /. Cooper et al.

samples and funding and the Ministry of Agriculture,Fisheries and Food, UK (MAFF).

References

BANER, A., BEIBER, W., FIGGE, K., FRANZ, R., and PIRINGER, O.,1992, Alternative fatty food simulants for migration testing ofpolymeric food contact materials. Food Additives andContaminants, 9, 137-148.

D E KRUIJF, N., and RIJK, M. A. H., 1988, Iso-octane as fatty foodsimulant: possibilities and limitations. Food Additives andContaminants, 5, 467-483.

D E KRUIJF, N., and RIJK, M. A. H., 1994, Test methods to simulatehigh-temperature exposure. Food Additives and Contaminants,11, 197-220.

EEC, 1990, Commission Directive NO 90/128/EEC of 23 February1990 relating to plastics materials and articles intended to comeinto contact with foodstuffs. Official Journal of the EuropeanCommunities, L 75, 21 March 1990.

EEC, 1993, Practical Guide N.1, Commission of the EuropeanCommunities, CS/PM/2024. DG III, Brussels, 2 April 1993.

EEC, 1996, Final draft '2nd amendment of Directive 82/711/EEC', III5441 96-Final, Brussels, 26 November 1996.

FDA, 1995, Recommendations for chemistry data for indirect foodadditive petitions. Washington DC, June 1995.

O'BRIEN, A., COOPER, I., and TICE, P. A., 1997, Correlation of specificmigration (Cf) of plastics additives with their initial concentra-tion in the polymer (Cp). Food Additives and Contaminants, 14,705-719.

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