I would like to specially thank my committee members of master thesis ...... pertaining to chemistry information that should be submitted in a food contact ... G. Hartman (Center for Advanced Food Technology, Rutgers University, NJ, USA).
EVALUATION OF ACCELERATED TEST PARAMETERS FOR MIGRATION TESTING OF FOOD PACKAGING By SHIN BAE KIM A thesis submitted to the Graduate School-New Brunswick Rutgers, The State University of New Jersey in partial fulfillment of the requirements for the degree of Master of Science Graduate Program in Food Science written under the direction of Dr. Thomas G. Hartman and approved by ________________________ ________________________ ________________________ New Brunswick, New Jersey January, 2011
ABSTRACT OF THE THESIS
EVALUATION OF ACCELERATED TEST PARAMETERS FOR MIGRATION TESTING OF FOOD PACKAGING By SHIN BAE KIM
Thesis Director: Dr. Thomas G. Hartman
This thesis focused on determining or evaluating accelerated analytical protocol for detecting potential migrants from food contact surface of conventional ink printed and/or UV/EB cured food packaging to food. Due to “offset transfer” effect of food packaging system, the need of fast and precise migration testing protocols emerged, which are in compliance with FDA recommendation and FDA guideline. In this study, variations of migration levels by change of testing parameters such as agitation, temperature, time, simulated solvent, and solvent volume/surface area ratio were investigated. Furthermore, the comparison studies of migration level between water soluble and insoluble compounds were performed. Single-side cell extraction and gas chromatography-mass spectrometry (GC-MS) were used to detect migrant compounds. Through the conclusion, 24-hour accelerated migration testing protocols are suggested and evaluated, which are regarded to be equivalent to the FDA recommended testing protocols.
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ACKNOWLEDGEMENTS
I would like to extend my sincere appreciation to my advisor, Dr. Thomas G. Hartman for his guidance, encouragement, support, and direction which aided in the completion of my study at Rutgers, the State University of New Jersey. I would like to specially thank my committee members of master thesis review, Dr. Chi-Tang Ho and Dr. Henryk Daun for their support and guidance throughout this study. My special thanks to Dr. Bin-Kong Khoo, Dr. Wudeneh Letchamo, Dr. Samia Mezouari and Joseph Lech for their assistance and friendship during my study at Mass Spec Lab, CAFT. I would also like to give special thanks to Dr. Sam Shefer and Dr. Adi Shefer in Salvona LLC. for offering great internship opportunity and their endless support. My sincere appreciation goes to my parents and parents-in-law as well as my family for their continued encouragement and endless love throughout my graduate work. Last but certainly not least my biggest thanks goes to my wife, Mi-Na Lim for being there by my side at all times. Her remarkable support and encouragement have made this study possible.
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TABLE OF CONTENTS TITLE .............................................................................................................................
i
ABSTRACT OF THESIS ............................................................................................... ii ACKNOWLEDGEMENTS ............................................................................................. iii TABLE OF CONTENTS ................................................................................................ iv LIST OF TABLES .......................................................................................................... vi LIST OF FIGURES ........................................................................................................ vii
I. INTRODUCTION ....................................................................................................... 1 II. LITERATURE REVIEW ............................................................................................ 3 A. General Information ......................................................................................... 3 1. Conventional ink printed packaging ........................................................... 3 2. UV/EB cured carton packaging .................................................................. 6 B. FDA Regulations Regarding Coating and Inks on Food Packaging ................ 9
C. Guidance for Industry: Preparation of Premarket Submissions for Food Contact Substances: Chemistry Recommendations (December 2007) .......... 11
III. RESEARCH HYPOTHESIS .................................................................................... 13 IV. EXPERIMENTAL .................................................................................................... 14 A. MATERIALS ................................................................................................ 14 B. METHODS ..................................................................................................... 17 1. Sample preparation with 10% ethanol, 3% acetic acid in water, or water simulant ................................................................................................... 18 2. Sample preparation with 95% ethanol simulant ....................................... 18
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3. Gas Chromatograph-Flame Ionization detection (GC-FID) analysis ....... 19 4. Factors affecting extraction efficiency ...................................................... 20 4.1. Conventional Ink base carton paperboard preparation .................... 20 4.2. EB/UV cured paperboard preparation ............................................. 20 4.3. Experimental design for identifying factors affecting extraction efficiency ..................................................................................... 21 V. RESULTS AND DISCUSSION ............................................................................... 23 A. Data Analysis of Migrants from Conventional Ink Packaging ...................... 23 1. Total migrants of “CONVENTIONAL INK” packaging system by conditions ............................................................................... 25 2. Comparision of Soluble and Insoluble Extractables from Conventional Ink Packaging ......................................................... 31 B. Data Analysis of Migrants from UV/EB Curable Packaging ........................ 38 3. Total migrants of “EB/UV CURABLE” packaging system by conditions ........................................................................................ 40 4. Comparision of Soluble and Insoluble Extractables from UV/EB Cured Packaging ..................................................................... 46 VI. CONCLUSION ......................................................................................................... 53 VII. REFERENCES ........................................................................................................ 55
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LIST OF TABLES 1. General conventional sheetfed ink composition ........................................................... 4 2. Comparison between conventional and UV/EB curable ink and coating ..................... 4 3. Commonly encountered UV/EB curable monomers used on food packaging prints ... 7 4. Recommended Food Simulants by US-FDA .............................................................. 12 5. Simulant volume to surface area ratio ........................................................................ 15 6. Percent recovery of the DCM and standard curves for the selected acrylate monomers in 10% and 95% aqueous ethanol simulant ...................................... 17 7. Design matrix for selected five factors with FDA level and range of our investigation ........................................................................................................ 21 8. Fractional factorial design matrix ............................................................................... 22 9. Detected representative extractables of conventional ink packaging ......................... 23 10. Solubilities of migrants of CONVENTIONAL INK printing packaging ................. 32 11. Detected representative extractables of EB/UV curable packaging ......................... 38 12. Solubilities of migrants of UV/EB Curable packaging ............................................. 47 13. Conditions for the 24-hour accelerated testing equivalent to FDA recommendation 54
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LIST OF FIGURES 1. Cross section of Typical Conventional Ink Printed Carton Board Packaging .............. 5 2. Cross section of Typical UV/EB Cured Carton Board Packaging ............................... 8 3. Diagram of single-side extraction cell for migration testing ...................................... 16 4. Chromatograph of Conventional Ink packaging extraction ........................................ 24 5. Total migrant level of Conventional ink packaging by Agitation variable ................ 25 6. Total migrant level of Conventional ink packaging by Simulated Solvent variable .. 26 7. Total migrant level of Conventional ink packaging by Time variable ....................... 27 8. Total migrant level of Conventional ink packaging by Temperature variable ........... 28 9. Total migrant level of Conventional ink packaging by Solvent volume/ Surface area Ratio (mL/Inch²) variable (ppb w/v unit) ....................................... 29 10. Total migrant level of Conventional ink packaging by Solvent volume/ Surface area Ratio (mL/Inch²) variable (ng/cm² unit) ........................................ 30 11. Migrant levels of soluble and insoluble compounds of ink-borne by Agitiation variable ......................................................................................... 33 12. Migrant levels of soluble and insoluble compound of ink-borne by Simulant variable ........................................................................................... 34 13. Migrant levels of soluble and insoluble compounds of ink-borne by Time variable ................................................................................................. 35 14. Migrant levels of soluble and insoluble compounds of ink-borne by Temperature variable ..................................................................................... 36 15. Migrant levels of soluble and insoluble compounds of ink-borne by Solvent volume/Surface area Ratio (mL/Inch²) variable (ng/cm² unit) .......... 37
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16. Chromatograph of EB/UV curable packaging extraction ......................................... 39 17. Total migrant level of EB/UV curable packaging extraction by Agitation variable . 40 18. Total migrant level of EB/UV curable packaging extraction by Simulant variable . 41 19. Total migrant level of EB/UV curable packaging extraction by Time variable ....... 42 20. Total migrant level of EB/UV curable packaging extraction by Temperature variable ................................................................................................................. 43 21. Total migrant level of EB/UV curable packaging extraction by Solvent Volume/Surface Area Ratio (mL/Inch²) variable (ppb w/v unit) ....................... 44 22. Total migrant level of EB/UV curable packaging extraction by Solvent Volume/Surface Area Ratio (mL/Inch²) variable (ng/cm²) ................................. 45 23. Migrant levels of soluble and insoluble compounds of UV/EB curable packaging by Agitiation variable .......................................................................................... 48 24. Migrant levels of soluble and insoluble compounds of UV/EB curable packaging by Simulated Solvent variable ............................................................................ 49 25. Migrant levels of soluble and insoluble compounds of UV/EB curable packaging by Time variable ................................................................................................. 50 26. Migrant levels of soluble and insoluble compounds of UV/EB curable packaging by Temperature variable ..................................................................................... 51 27. Migrant levels of soluble and insoluble compounds of UV/EB curable packaging by Solvent Volume/Surface Area Ratio (mL/Inch²) variable (ng/cm²) ............... 52
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1
I. INTRODUCTION
Printed paperboard carton packaging is one of the most broadly used packaging materials for foods such as dairy products, fruit juices and frozen foods. The outer, nonfood contact surface of the packaging is typically heavily printed with inks and then a clear overprint varnish (OPV) is applied to convey abrasion resistance. Printing inks broadly fall into one or two categories, conventional or energy curable. Conventional inks and coatings are water or solvent based systems that are applied to the surface and then dried or cured. Energy curable systems are solventless and use ultra-violet (UV) or electron beam (EB) irradiation to cure the inks and coatings. Both conventional and energy curable inks and OPV are composed of a plethora of chemicals including solvents, pigments, resins, plasticizers, surfactants, antioxidants, UV-photoinitiators and many other compounds, none of which are generally recognized as safe (GRAS) food additives by the US Food and Drug Administration (FDA) (Yoo, Pace, Khoo, Lech and Hartman, 2004). According to FDA regulations, the food packaging must be a functional barrier to the non-GRAS chemicals used in inks and coatings. Printed food packaging flatstock and/or rollstock is stored before use with the printed/coated side of the packaging in direct physical contact with the unprinted food contact surface. In this orientation, ample opportunity for the transfer of printing/coating chemicals to the food contact surface exists. The phenomenon whereby ink or OPV chemicals migrate from the print side to the food contact side is called “offset transfer”. FDA limits migration via this mechanism to 50 parts per billion (ppb) for each non-GRAS substance and requires extraction testing with food simulating solvents for regulatory compliance (FDA, 2007). Typical FDA
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extraction studies take up to 10 days or more to complete. This time constraint is problematic for industry in that quick decisions must often be made on suitability of packaging.
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II. LITERATURE REVIEW A. General Information 1. Conventional ink printed packaging Conventional ink printing is a solvent based system. In order to obtain a “quick set” effect, generally low viscosity, low aromatic mineral oils are applied. However, when inks are printed on non-absorbent substrates such as plastics, it is hard to expect “quick set” effect. The general conventional sheetfed ink composition is shown on Table 1. Due to solvent based system, conventional ink printing and coating take relatively over time for drying and coating. Moreover, conventional ink printing process requires high temperature environment for effective drying process during absorbing or evaporating excessive ink and solvent or water, or a combination of both. The penetration of the low viscosity oils into the substrate also induces a physical drying (setting). The rollers for conventional inks are typically Nitrile Butadiene rubber (NBR) which is compatible with more apolar materials such as hydrocarbons, whereas rubber rollers for UV inks are based on EPDM (ethylene propylene diene Monomer (M-class) rubber, a type of synthetic rubber), (Gevaert, 2010). The general comparison between conventional and UV/EB curable ink and coating is shown on Table 2. In addition, the cross sections of typical conventional ink printed carton board packaging are shown on Figure 1. The Figure 1. shows general two types of conventional printings, surface printing and reverse printing. Because the paperboard with surface print is more prone to offset transfer, reverse printing paperboard is used for our research.
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Table 1. General conventional sheetfed ink composition (Gevaert, 2010) Conventional Sheetfed Ink Mineral Oil (280-320°C)
0-30%
(semi) Drying vegetable oil and esters thereof
15-30%
Drying alkyd
10-20%
Hard resin (rosin mod)
20-35%
Pigment
14-24%
Fillers
0-5%
Wax
3-5%
Driers
2%
Anti-oxidants
0-2%
Table 2. Comparison between conventional and UV/EB curable ink and coating Printing Ink
Conventional
Energy(Radiation) Curable
System
Water or Solvent
Solventless
Speed
Slow Drying and Coating
Fast Curing
Operation Temp.
High (for drying)
Room Temp.
Cost
High
Low
VOC’s Emitting*
High
Few
Quality
Less
Higher
*VOC: volatile organic compounds
5
Figure 1. Cross section of Typical Conventional Ink Printed Carton Board Packaging (A. Surface Printed ; B. Reverse Printed)
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2. UV/EB cured carton packaging
Ultraviolet (UV) and/or Electron beam (EB) cured packaging system has been popular since its commercialization in late 1960’s. Because of its prominent advantages such as fast cure speed, room temperature operation, high quality end products and economic cost, UV/EB cured packaging has been used in broad area for food packaging industry. As known cool and solventless process, UV/EB curing system fulfils the US Environmental Protection Agency (US-EPA) recommendation by decreasing the use of volatile organic compounds (VOS’s), incinerators and/or solvent recovery units (Yoo, 2004). Curing is the toughening or hardening of a polymer material by cross-linking of polymer chains (Wikipedia, 2008) and the chemical reaction that a material goes through to get from the wet to the dry stage (Utschig, 2004). Thus, in UV/EB curing to produce polymers, generally acrylate monomers and oligomers are used for food packaging. The most mainly used acrylate monomers are shown on Table 3. For UV curing, photoinitiators (PIs) which induce photopolymeization or photocross-link of the acrylate resins are applied. Fouassier explained the two-step process of photoinitiation in his book; PIs absorb the UV energy to convert to free radicals and then free radicals attack and break the acrylic double bonds to initiate polymerization (Fouassier, 1995). On the other hand, for EB curing, the acrylic double bonds are attacked by the high energy of accelerated electrons, which directly initiate polymerization of the ink or coating (Leach, 1998 and Rechel, 2001). Furthermore, application of propoxylation and ethoxylation has
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been broadly accepted in the ink and coating industry. Both propoxylation and ethoxylation are to induce cross-linking between oligomer molecules and other monomers and to increase complexity of the structure of polymers.
Table 3. Commonly encountered UV/EB curable monomers used on food packaging prints Common Name
Chemical Name
TPGDA
Tripropylene glycol diacrylate
TMPTA
Trimethylol propane triacrylate
HDDA
1,6 hexane diol diacrylate
DPGDA
Dipropylene glycol diacrylate
PETA
Pentaerythritol tri-, tetraacrylate
NVP
N-vinylpyrrolidone
ODA
Octyl decyl acrylate
OH-Butyl acrylate
Butanediol monoacrylate
EO-TMPTA
Ethoxylated trimethylol propane triacrylate
EO-HDDA
Ethoxylated 1,6 hexane diol diacrylate
GPTA
Glyceryl propoxylated triacrylate
PO-NPGDA
Propoxylated neopentyl glycol diacrylate
di-TMPTA
Di-Trimethylol propane tetraacrylate
8
Figure 2. Cross section of Typical UV/EB Cured Carton Board Packaging
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B. FDA Regulations Regarding Coating and Inks on Food Packaging
FDA permits the use of conventional & energy curable inks and coating as components of food packaging under certain conditions in compliance with certain regulations. Actually, conventional inks are able to be utilized onto direct food contact side with approved functional barrier or FDA acceptable coating such as resinous coating, protective film, transparent cover, etc. by FDA (Gettis, 1997). The FDA states that if printed material is separated by approved functional barrier, the printing ink ingredients would not need to be approved for that use (Gettis, 1997). However, the UV/EB inks and coatings are not approved for direct food contact due to their safety concern. Whatever the ink or coating substances are approved to be applied onto direct or indirect food contact side of food packaging or not, migration of the chemical substances from food packaging to food is strictly restricted by FDA regulation. According to No-Migration exemption, clarified by the United States Court of Appeals for the D.C. circuit in Monsanto v. Kennedy decision (D.C.Cir.1979), the term “food additive” has been clearly defined as : “Food additives includes all substances not exempted by section 201(s) of the Federal Food, Drug, and Cosmetic Act, the intended use of which results or may reasonably be expected to result, directly or indirectly, either in their becoming a component of food or otherwise affecting the characteristics of food. A material used in the production of containers and packages is subject to the definition if it may reasonably be expected to become a component, or to affect the
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characteristics, directly or indirectly, of food packed in the container. "Affecting the characteristics of food" does not include such physical effects, as protecting contents of packages, preserving shape, and preventing moisture loss. If there is no migration of a packaging component from the package to the food, it does not become a component of the food and thus is not a food additive. A substance that does not become a component of food, but that is used, for example, in preparing an ingredient of the food to give a different flavor, texture, or other characteristic in the food, may be a food additive.”(21 Code of Federal Regulations (CFR) 170.3(e) Food Additives, Definitions) In addition, a substance, detected at below 50 part per billion (ppb) with an appropriately conducted migration study, is considered to be not a food additive. The migration study should be conducted in accurately simulated conditions of actual use. There is also a proper guideline for migration study according to the FDA, entitled “Guidance for Industry: Preparation of Premarket Submissions for Food Contact Substances: Chemistry Recommendations (December 2007).” At Code of Federal Regulations, Title 21, parts 170, 39, “Threshold of regulation for substances used in food-contact articles” of FDA stipulates the proposition for the substances which can be considered as safe on the basis of low dietary exposure. The substance at extremely low levels, 0.5 PPB or below in the diet may be considered as GRAS.
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C. Guidance for Industry: Preparation of Premarket Submissions for Food Contact Substances: Chemistry Recommendations (December 2007)
The Federal Food, Drug, and Cosmetic Act (the Act) at sec409 (h) (6) defines the food-contact substance (FCS) as “any substance that is intended for use as a component of materials used in manufacturing, packing, packaging, transporting, or holding food if the use is not intended to have any technical effect in the food” (FDA, 2007). As well, the section 409 of the Act includes the requirements for food contact notification (FCN) or food additive petition (FAP), which involve “sufficient scientific information to demonstrate that the substance that is the subject of the submission is safe under the intended conditions of use” (FDA, 2007). This guidance for industry (FDA, 2007) contains “FDA's recommendations pertaining to chemistry information that should be submitted in a food contact notification (FCN) or food additive petition (FAP) for a food-contact substance (FCS)” (FDA, 2007). Especially, in ‘section II. Chemistry information for FCNs and FAPs’, the document describes migration testing and analytical methods in detail such as design of migration experiment (II D 1 A-E), characterization of test solutions & data reporting (II D 2), analytical methods (II D 3 A-E), migration database (II D 4), and migration modeling (II D 5). The specifications of migration cell, test sample, food stimulants, temperature, and time of test are well explained in the section of design of migration experiment. For example, the document shows food simulant samples for test, as shown at Table 4. The
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guidance also recommends 10 mL/Inch² for the acceptable ratio of specimen volume/ surface area when it is not able to be similar to the ratio of actual food packaging. For temperature and time of testing, a test temperature of 40 ºC (104 ºF) for room temperature application and 20 ºC (68 ºF) for refrigerated or frozen food applications were acceptable for 10 days each instead of the recommendation of FDA, the most severe conditions of temperature and time anticipated for the proposed use (FDA, 2007).
Table 4. Recommended Food Simulants by US-FDA Food-Type as defined in 21 CFR 176.170(c) Table 1 Aqueous & Acidic Foods (Food Types I, II, IVB, VIB, and VIIB)
Low- and High-alcoholic Foods (Food Types VIA, VIC)
Fatty Foods (Food Types III, IVA, V, VIIA, IX)
Recommended Simulant
10% Ethanol
10 or 50% Ethanol*
Food oil (e.g., corn oil), HB307, Miglyol 812, or others**
* Actual ethanol concentration may be substituted ** HB307 is a mixture of synthetic triglycerides, primarily C10, C12, and C14. Miglyol 812 is derived from coconut oil
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III. RESEARCH HYPOTHESES
Accelerated analytical methods can be evaluated to assess the migration potential of ink-borne from conventional ink printed packaging and/or UV/EB curable components, which migrates from food contact surface of printed food packaging to foods. The evaluation can prove that accelerated analytical methods can be equivalent to FDA recommended protocols and satisfying FDA recommendations. Accelerated parameters such as agitation, increased temperature, and intensified ratio of simulant volume to surface area of sample, and various simulated solvents can hasten the migration speed of ink-bornes or UV/EB curable ink components. Thus, extraction testing can be shortened in 24 hours rather than 10 days. Also, comparison of water soluble and insoluble compounds among the migrants of can confirm that accelerated analytical methods are valid to both water soluble and insoluble compounds. We anticipate that changing and/or accelerating the affecting factors may cause similar effects to both water soluble and insoluble compounds for both conventional ink printed packaging experiments and UV/EB cured packaging experiments. Thus, based on the evaluation, optimized and accelerated analytical methods will be suggested through the experiments. Then, we expect that the results of optimized and accelerated (24 hours) migration testing will be equivalent to those of the FDA migration testing.
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IV. EXPERIMENTAL A. MATERIALS Single side extraction cells were used for migration testing. To extract conventional ink elements and/or EB/UV curable components from the one-side surface of food packaging prints, single side extraction cells were designed according to FDA specifications for food contact polymer migration testing and developed by Dr. Thomas G. Hartman (Center for Advanced Food Technology, Rutgers University, NJ, USA). Single side extraction cells consist of two stainless steel plates which sandwich a Teflon gasket (Teflon spacer) assembly and screws as shown Figure 3. The Teflon gasket isolates 51 cm² (7.9 inch²) surface area of only the food contact surface or direct printed/coated surface for extraction. Also, the Teflon gaskets (spacers) can hold 30mL, 62.5mL or 125mL of food simulant volumes accordingly their sizes. The ratios of stimulant volumes to surface area of a substrate are 3.8, 7.9 or 15.8, respectively. Due to FDA recommendation of testing, the ratio of 10, 125mL Teflon gasket is selected with 79mL of simulant. A specimen, of which the food contact surface is facing up, was put on the top of bottom plate. A Teflon spacer which has cavity for food simulant was placed on the specimen’s food contact surface. Then, the top plate was put on the Teflon spacer. All together was tightened up by 12 screws. Through the hole of the top plate, the food simulant was injected into the assembled extraction cell. As internal standards, approximately 100 ppb level of anthracene d-10 and/or ndocosane were matrix-spiked into the extracts. Then, the extracts were concentrated
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Table 5. Simulant volume to surface area ratio
Surface area of a
Simulant volume / surface
specimen (in²)
area Ratio (mL/in²)
7.9
7.9
1
23.7
7.9
3
39.5
7.9
5
79
7.9
10*
Simulant Volume (mL)
* The ratio, the FDA recommended, of simulant volume to surface area of a specimen.
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Figure 3. Diagram of single-side extraction cell for migration testing (designed by Dr. Thomas G. Hartman, Center for Advanced Food Technology (CAFT), Rutgers University, NJ)
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B. METHODS The methods used for my experiment were validated by Yoo, S.J. in his dissertation in 2005. According to Yoo’s dissertation, the method accuracy (percent recovery) of selected acrylate monomers such as TPGDA, TMPTA, HDDA, EO-HDDA, EO-TMPTA, and GPTA in DCM were within FDA’s acceptable ranges as shown in Table 6. (Yoo., 2005).
Table 6. Percent recovery of the dichloromethane (DCM) and standard curves for the selected acrylate monomers in 10% and 95% aqueous ethanol simulant (Yoo., 2005).
Recovery percentage* Acrylate monomer
In 10% aqueous ethanol
In 95% ethanol
TPGDA
97.9%
98.5%
TMPTA
99.0%
97.8%
HDDA
98.1%
99.7%
EO-HDDA
87.8%
95.5%
EO-TMPTA
90.5%
94.6%
GPTA
85.4%
81.9%
FDA acceptable levels**
80-110% At below 100ppb Levels in foods
* The analysis was performed in triplicate and % was mean of triplicates. Relative standard deviation (RSD %) of each acrylate monomers was below 11%. ** Validation of analytical methods (II. D.3. e.), In Guidance for Industry: “Preparation of food contact Notification and Food Additives Petitions for Food Contact Substances”: Chemistry Recommendations, Final Guidance, April (2002).
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1. Sample preparation with 10% ethanol, 3% acitic acid in water, or water simulant 8mL, 24mL, 40mL or 80mL of solvent simulants such as 10% aquous ethanol, 3% acitic acid in water, or water were incubated in single-side extraction cell in controlled circumstances. After incubation, those simulants were transferred from extraction cells into 50mL or 100mL size test tubes which have Teflon-lined cover. 100 ppb internalstandards were matrix-spiked into each sample simulant. Anthracene-d10 in dichloromethane (DCM) and n-C22 Docosane in DCM were chosen as internal standards (approximately 1.0 mg acrylate/10 mL DCM). The reason why two internal standards were used was to avoid the confliction between internal standard and extractedcompound such as TMPTA. For example, each of 0.8µL of internal standards was spiked into 8mL stimulants and 2.4µL of internal standards into 24mL simulants. Then, 5mL of DCM was added into the sumulants to vigorously back-extracted. The simulants were vigorously hand-shaken for 10 minutes and centrifuged at 3000 rpm for 30 minutes. The extracts at bottom layer were taken and concentrated to approximately 0.1mL using gentle stream of nitrogen at room temperature. The concentrated extracts were analyzed by Gas Chromatography-Flame Ionization Detector (GC-FID).
2. Sample preparation with 95% ethanol simulant 24mL of 95% ethanol simulant was incubated in single-side extraction cell in controlled circumstances. After incubation, the simulant was transferred from extraction cells into 50mL size test tubes which have Teflon-lined cover. 100 ppb internal-standards
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were matrix-spiked into sample simulant (2.4µL of internal standards). Anthracene-d10 in DCM and n-Docosane(C-22) in DCM were chosen as internal standards (approximately 1.0 mg/10 mL DCM). Then, the simulant was vortexed. 5mL of simulant was taken and transferred into another 50mL size test tube. 42.5mL of water was added into the test tube in order to make 10% aqueous ethanol solution by dilution. After voltexing it, 5mL of DCM was added into the sumulant to back-extract compounds. The simulant was vigorously hand-shaken for 10 minutes and centrifuged at 3000 rpm for 30 minutes. The extracts at bottom layer were taken and concentrated to approximately 0.1mL using gentle stream of nitrogen at room temperature. The concentrated extracts were analyzed by Gas Chromatography-Flame Ionization Detector (GC-FID).
3. Gas Chromatograph-Flame Ionization detection (GC-FID) analysis GC-FID analyses were performed on a Varian 3400 gas chromatograph with flame ionization detector (GC-FID). The data were acquired and processed with PeakSimple™. The temperature of injector was 280ºC with splitless injection. After 30 seconds, 100:1 split was programmed with septum purge. The 1µL injection of the analyte in DCM (methylene chloride) was made on MDN-5S (Supelco, Serial# M89501B), Fused Silica Capillay Column, 30m x 0.32mm ID x 0.25µm. Helium was the carrier gas at 10 psi pressure. The GC oven temperature was defined from 50ºC, held for 3 minutes, and then increased up to 320ºC at a rate 10ºC/min, then held at 320ºC for 10 minutes.
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4. Factors affecting extraction efficiency 4.1. Conventional Ink Base carton paperboard preparation Conventional ink based carton paperboard samples were prepared at Carton Services Packaging Insights in Shelby Ohio. The substrate is F230H grade Waynsville coated board stock. The samples were made for “Will’s Fresh Foods” products. Samples were printed with the reverse printing method. Sections of each carton sample measuring 10cm x 15cm were cut and placed into a custom stainless steel (SS) extraction cell (single-side extraction cell), as described above.
4.2. EB/UV cured paperboard preparation EB/UV cured (printed/coated) Minute Maid Fruit Punch Carton paperboards were prepared at Blue Ridge Paper Products Division, Evergreen Packaging at Waynesville, NC. Sections of each carton sample measuring 10cm x 15cm were cut and placed into a custom stainless steel (SS) extraction cell (single-side extraction cell), as described above.
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4.3. Experimental design for identifying factors affecting extraction efficiency Five factors – temperature, time, surface area to simulant volume ratios, agitation and solvent strength- were considered and selected as potentially affecting extraction efficiency, according to the FDA recommended testing conditions. In order to identify and clarify of the affectability of each parameter, fractional factorial design was set up as on Table 8. The testing was triplicated and the results were analyzed. The levels of the conditions also were based on FDA recommended testing conditions. FDA recommended testing conditions had to be minimum levels to investigate our accelerated optimum conditions. FDA recommended testing conditions are shown on Table 7.
Table 7. Design matrix for selected five factors with FDA level and range of our investigation Solvent
Agitation**
Temperature
Volume to
Solvent
(°C)
Surface Ratio
Strength
Time
(mL/Inch²)
FDA*
No
Range of our investigation
No or Full
Room Temp. Room tm. 40, 60, or 80
10
10% EtOH
1,3,5, or 10
10%, 95% EtOH, 3% aqueous Acetic Acid, or Water
10 days 1, 4, or 10 days
*FDA recommended conditions for aqueous & acidic foods for room temperature application. ** Agitation was performed by voltexing incubator (New Brunswick Scientific Products.)
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Table 8. Fractional factorial design matrix. EXP. No.
Sample
Temp.
Agitation
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
1* 1 2** 2 1 1 1 1 2 2 2 2 1 1 1 2 2 2 1 1 1 1 2 2 2 2 1 1 1 1 2 2 2 2
40°C 40°C 40°C 40°C 40°C 40°C 40°C 40°C 40°C 40°C 40°C 40°C 40°C 40°C 40°C 40°C 40°C 40°C Rm. 40°C 60°C 80°C Rm. 40°C 60°C 80°C 40°C 40°C 40°C 40°C 40°C 40°C 40°C 40°C
O X O X O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O
Solvent Volume/Surface Area Ratio (mL/In²) 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 1 3 5 10 1 3 5 10
Time 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 4 Days 10 Days 24 Hrs. 4 Days 10 Days 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs. 24 Hrs.
Simulated Solvents 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 95% EtOH 3% Acetic in H2O
H2O 10% EtOH 95% EtOH 3% Acetic in H2O
H2O 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH 10% EtOH
* Sample 1 is for Conventional Ink packaging test produced by Carton Service, Packaging Insights ** Sample 2 is for EB/UV cured packaging test produced by Evergreen Packaging EB printed Carton LLN5045
23
V. RESULTS AND DISCUSSION A. Data Analysis of Migrants from Conventional Ink Packaging Through the single side extraction cell experiment of conventional ink packaging, which followed FDA recommended testing conditions, tens of elements were migrated and detected. Representative detected extractables of conventional ink packaging are listed on Table 9. Our food contact side extraction of the conventional ink printed packaging carton showed relatively high levels of ink-borne migrants. Significant counts of compounds were non-GRAS. Some of them exceeded the FDA threshold of 50 ppb w/v such as cyclohexanone, 2-ethylhexyl alcohol, acetophenone, 2-ethylhexyl acetate, diethylene glycol, monobutyl ether, Surfynol 104, Kodaflex TXIB type ester alcohol plasticizer, and dipropylene glycol, monobenzoate isomer. Table 9. Detected representative extractables of conventional ink packaging 1 2 3 4 5 6 7 8
cyclohexanone 2-ethylhexyl alcohol acetophenone 2-ethylhexyl acetate diethylene glycol, monobutyl ether diethylene glycol, monobutyl ether acetate 2,4,7,9-tetramethyl-5-decyn-4,7-diol (Surfynol 104) propylene glycol, monobenzoate 2,2,4-Trimethyl-1,3-Pentanediol Diisobutyrate 9 (Kodaflex TXIB type ester alcohol plasticizer) Ethoxylated tetramethyldecynediol 10, 13 (Surfynol 440 oligomer: Surfynol 104 polyethoxylate oligomer) 11, 12 dipropylene glycol, monobenzoate isomer 14 dipropylene glycol, dibenzoate 15 D-10 anthracene (internal standard) 16 n-c22Docosane (internal standard)
24
Figure 4. Chromatograph of Conventional Ink packaging extraction
* Numbered compounds on the chromatograph are listed on Table 9.
** Chromatograph of experiment number 21-1 on Table 8. ; With agitation, 1 day, 10% ETOH, 60 ºC, 3mL/in² (agitation, extraction duration, food simulant, temperature, and solvent/surface ratio, respectively)
25
1. Total migrants(ppb) of “CONVENTIONAL INK” packaging system by conditions 1.1. Agitation variable Holding other factors constant - 1 day, 10% ETOH, 40 ºC , 3mL/in² (extraction duration, food simulant, temperature, and solvent/surface ratio respectively) -, the total migrant levels are 1165.72 ppb with agitation and 1142.77 ppb without agitation, respectively, as shown on Figure 5. The level difference of total migrants of conventional ink packaging is insignificant.
Figure 5. Total migrant level of Conventional ink packaging by Agitation variable Total Migrants (ppb)
ppb 1400.00 1200.00
1165.72
1142.77
with Agit.
without Agit.
1000.00 800.00 600.00 400.00 200.00 0.00
* Concentrations of total migrants are mean of three experiments.
26
1.2. Simulated Solvent variable As shown Figure 6., holding other factors constant - 1 day, with agitation, 40 ºC , 3mL/in² (extraction duration, agitation, temperature, and solvent/surface ratio respectively) -, the total migrant levels were 1177.42 ppb with 10% EtOH, 7012.24 ppb with 95% EtOH, 860.87 ppb with 3% Acetic Acid in Water, and 1049.92 ppb with Water, respectively. The solvent strength had a significant effect on extraction. The other solvents affected similarly in conventional ink extraction.
Figure 6. Total migrant level of Conventional ink packaging by Simulated Solvent variable
Total Migrants (ppb) ppb 8000.00 7012.24 7000.00 6000.00 5000.00 4000.00 3000.00 2000.00
1177.42
1000.00
860.87
1049.92
3% Acetic Acid in Water
Water
0.00 10% ETOH
95% ETOH
* Concentrations of total migrants are mean of three experiments.
27
1.3. Time variable Through the experiments #13-15 on Table 8., time variable tests were performed. With other factors constant - 10% ETOH, with agitation, 40 ºC , 3mL/in² (food simulant, agitation, temperature, and solvent/surface ratio respectively) -, the total migrant levels are 1016.91 ppb with 1 day extraction, 1383.22 ppb with 4 days, and 1814.11 ppb with 10 days, respectively. As incubation time increased, the level of total migrants rose. 10 days experiment had only about 1.8 times total migrant level than 1 day experiment. This is insignificant difference. The migrant level of 10 days extraction is close to the recommended level for FDA test.
Figure 7. Total migrant level of Conventional ink packaging by Time variable
Total Migrants (ppb)
ppb 2000.00
1814.11
1800.00 1600.00
1383.22
1400.00 1200.00
1016.91
1000.00 800.00 600.00 400.00 200.00 0.00 24 Hours
4 Days
10 Days
* Concentrations of total migrants are mean of three experiments.
28
1.4. Temperature variable On temperature variable test, the total migrant levels are 350.41 ppb at 25 ºC, 1177.42 ppb at 40 ºC, 2159.38 ppb at 60 ºC, and 2891.43 ppb at 80 ºC, respectively, while other factors were constant - 1 day, with agitation, 10% ETOH, 3mL/in² (extraction duration, agitation, food simulant, and solvent/surface ratio respectively). The higher temperature, the more migrant levels there are. The migration of conventional ink components was significantly sensitive on temperature parameters.
Figure 8. Total migrant level of Conventional ink packaging by Temperature variable
Total Migrants (ppb)
ppb 3500.00
2891.43
3000.00 2500.00
2159.38
2000.00 1500.00
1177.42
1000.00 500.00
350.41
0.00 25 ℃
40 ℃ *
60 ℃
80 ℃
* 40 ºC data is duplicated from the Simulated Solvent Variables experiment because of same parameter conditions. ** Concentrations of total migrants are mean of three experiments
29
1.5. Solvent Volume/Surface Area Ratio (mL/INCH²) variable The ratio of solvent volume per surface area (mL/In²) variable experiments showed that total migrant level of conventional ink extractables decreased on ppb (w/v) unit as the ratio increased, as shown on Figure 9. However, when the unit was normalized onto ng/cm², total migrant level of extractables increased gradually as the increment of the ratio, as shown on Figure 10.
Figure 9. Total migrant level of Conventional ink packaging by Solvent volume/Surface area Ratio (mL/Inch²) variable (ppb w/v unit)
Total Migrants (ppb)
ppb 3000.00 2500.00
2349.62
2000.00 1500.00 1133.65 893.51
1000.00
642.37 500.00 0.00 1 mL/Inch²
3 mL/Inch²
5 mL/Inch²
10 mL/Inch²
30
Figure 10. Total migrant level of Conventional ink packaging by Solvent volume/Surface area Ratio (mL/Inch²) variable (ng/cm² unit)
Total Migrants (ng/cm²)
ng/cm2 1200.00
1007.64 1000.00 800.00
700.79 533.48
600.00 400.00
368.57
200.00 0.00 1 mL/Inch²
3 mL/Inch²
5 mL/Inch²
* This is the normalized analysis.
10 mL/Inch²
31
2.
Comparison of Soluble and Insoluble Extractables from Conventional Ink
Packaging The comparisons between water soluble and insoluble compounds at conventional ink extract experiment were performed in order to identify the differences of extractability by parameters. The water solubility of each element is listed on Table 10. As examples, diethylene glycol, monobutyl ether acetate (CAS# 124-17-4) and dipropylene glycol, dibenzoate (CAS# 94-51-9) were chosen for representatives of water soluble and insoluble compounds, respectively. The reason why diethylene glycol, monobutyl ether acetate (CAS# 124-17-4) was selected is that diethylene glycol, monobutyl ether acetate has the solubility of 65g/L, which is the biggest solubility among the extractables. Also, diethylene glycol, monobutyl ether acetate (CAS# 124-17-4) was extracted in significant amount at almost all of our experiments, which was over the FDA regulation -50 ppb w/v- for non-GRAS compound. Monobutyl ether acetate was one of most extracted element from conventional ink packaging cell-extraction as well as obvious one of water insoluble extractables.
32
Table 10. Solubilities of migrants of CONVENTIONAL INK printing packaging
CAS Number
Water Solubility
Other Solubility Miscible in ethanol and common organic solvents
Cyclohexanone
108-94-1 9075-99-4
slightly soluble (5-10 g/100 mL) 150 g/L (10 ºC)
2-ethylhexyl alcohol
104-76-7 111675-57-1 (FEMA No. 3151)
1 g/L (20 ºC)
Acetophenone
98-86-2
5.5 g/L at 25°C 12.2 g/L at 80°C
2-ethylhexyl acetate
103-09-3
slightly soluble
112-34-5
soluble
diethylene glycol, monobutyl ether diethylene glycol, monobutyl ether acetate Surfynol 104 propylene glycol, monobenzoate Kodaflex TXIB type ester alcohol plasticizer (2,2,4-Trimethyl-1,3Pentanediol Diisobutyrate) Surfynol 440 oligomer (Surfynol 104 polyethoxylate oligomer) dipropylene glycol, monobenzoate isomer dipropylene glycol, dibenzoate
124-17-4 98100-70-0 126-86-3 8043-35-4
65 g/L 1.5 g/L (20 °C)
37086-84-3
14.57-38.2(g/L) at 25°C
6846-50-0
1.5mg/L
9014-85-1
Immiscible with water
32686-95-6
N/A
94-51-9 27138-31-4
insoluble
soluble in sulfuric acid and most organic solvents
33
2.1. Agitation variable Through the agitation variable test, as shown in Figure.. diethylene glycol, monobutyl ether acetate was extracted about 50 % more with agitation than without agitation. The extracted compound levels of diethylene glycol, monobutyl ether acetate were 92.11 ppb with agitation and 59.54 without agitation, respectively. On the other hand, dipropylene glycol, dibenzoate had similar level of migration in with and without agitation extraction experiment. Other controlled parameters were 40°C, 1 day incubation, 10% EtOH simulant, and 3mL/Inch² ratio.
Figure 11. Migrant levels of soluble and insoluble compounds of ink-borne by Agitiation variable
ppb 100.00
diethylene glycol, monobutyl ether acetate
dipropylene glycol, dibenzoate ppb 450.00
92.11
90.00
400.00
80.00
350.00
70.00
with Agit.
without Agit.
250.00
50.00
200.00
40.00
150.00
30.00 20.00
100.00
10.00
50.00
0.00
0.00 with Agit.
350.42
300.00
59.54
60.00
351.20
without Agit.
34
2.2. Simulated Solvent variable Figure 12. shows that both water soluble and insoluble migrants (diethylene glycol, monobutyl ether acetate and dipropylene glycol, dibenzoate) are around three times extractable with 95% EtOH simulant solvent than with other simulant solvents. As known in the variation of the total migrant levels by simulant solvent from Figure 12., solvent strength was also significantly affecting factor for water soluble and insoluble migrant extractions.
Figure 12. Migrant levels of soluble and insoluble compound of ink-borne by Simulant variable
ppb 350.00
dipropylene glycol, dibenzoate
diethylene glycol, monobutyl ether acetate
ppb 1800.00 1600.00
300.00
265.88
1406.89
1400.00
250.00
1200.00 200.00
1000.00
150.00
800.00
100.00
600.00 73.18
57.90
62.52
400.00
50.00
223.71
282.28
200.00
0.00
0.00 10% ETOH95% ETOH 3% Acetic Water Acid in Water
353.87
10% ETOH
95% 3% Acetic Water ETOH Acid in Water
35
2.3. Time variable On the time variable experiments, the data showed that incubating duration had slight affect for water soluble and insoluble extractatbles, as shown at Figure 13. The figure indicated that the level of diethylene glycol, monobutyl ether acetate had decreased slightly after 10 days incubation than 4 days experiments. There could be degradation or change of diethylene glycol, monobutyl ether acetate to diethylene glycol, monobutyl ether due to its stability. On the other hand, dipropylene glycol, dibenzoate increased slightly by longer extraction.
Figure 13. Migrant levels of soluble and insoluble compounds of ink-borne by Time variable diethylene glycol, monobutyl ether acetate ppb 120.00
dipropylene glycol, dibenzoate ppb 500.00
110.32
450.00 400.00
100.00 85.98 80.00
394.41
350.00
79.35
418.27
335.93
300.00 250.00
60.00
200.00 150.00
40.00
100.00 20.00
50.00 0.00
0.00 24 Hours
4 Days
24 Hours
10 Days
4 Days
10 Days
36
2.4. Temperature variable Figure 14. shows that generally the higher temperature extracted the more extractables on both water soluble and insoluble compounds except at 60°C diethylene glycol, monobutyl ether, 117.90 ppb w/v which was higher than extracted level at 80°C. Diethylene glycol, monobutyl ether was not found at 25°C extraction experiment.
Figure 14. Migrant levels of soluble and insoluble compounds of ink-borne by Temperature variable
ppb 140.00
diethylene glycol, monobutyl ether acetate
ppb
dipropylene glycol, dibenzoate
800.00 117.90
120.00
600.00
94.66
100.00
516.43
500.00
73.18
80.00
680.69
700.00
400.00 60.00
353.87
300.00
40.00
200.00
20.00
144.67
100.00 0.00
0.00
0.00 25 ℃
40 ℃ *
60 ℃
25 ℃
80 ℃
40 ℃ *
60 ℃
80 ℃
* 40 ºC data is duplicated from the Simulated Solvent Variables experiment because of same parameter conditions.
37
2.5. Solvent Volume/Surface Area Ratio (mL/Inch²) variable As shown on Figure 15., migrant levels of soluble and insoluble compounds of ink-borne by solvent volume/surface area ratio (mL/Inch²) had similar pattern. With the normalized unit (ng/cm²), migrant levels increased gradually along with the increment of solvent volume/surface area ratio (mL/Inch²). To soluble substrate, diethylene glycol, monobutyl ether acetate, migrant level of 10 mL/Inch² was 48.85 ng/cm² which was less than double of 1 mL/Inch², 27.06 ng/cm². To insoluble compounds, dipropylene glycol, dibenzoate, migrant level of 10 mL/Inch² was 217.18 ng/cm² which was slightly more than double of 1 mL/Inch², 94.05 ng/cm².
Figure 15. Migrant levels of soluble and insoluble compounds of ink-borne by Solvent volume/Surface area Ratio (mL/Inch²) variable (ng/cm² unit)
ng/cm2 60.00
diethylene glycol, monobutyl ether acetate 48.85
50.00 38.10
40.00 30.00
ng/cm2 300.00 250.00
37.56
217.18
200.00
27.06
169.01
159.38
150.00
20.00
100.00
10.00
50.00
0.00
0.00
94.05
1 3 5 10 mL/Inch² mL/Inch² mL/Inch² mL/Inch²
1 3 5 10 mL/Inch² mL/Inch² mL/Inch² mL/Inch²
dipropylene glycol, dibenzoate
38
B. Data Analysis of Migrants from UV/EB Curable Packaging The data of single side cell extraction of EB/UV cured carton board packaging are shown on Table 11. and Figure 16. A number of EB-ink and coating-borne were extracted by food contact side cell extraction. TMPTA and combined eo-TMPTA oligomers exceeded the FDA threshold of 50 ppb w/v at almost all of our experiments. There were couple of peaks confliction between TMPTA and d-10 anthracene at experiment number in Table.. In these cases, internal standard, d-10 anthracene, was substituted with c-22 docosane.
Table 11. Detected representative extractables of EB/UV curable packaging 1
Diethylene glycol monobutyl ether (Dowanol DB)
2
Hydroquinone methyl ether (MEHQ inhibitor)
3
Azepan-2-one (Caprolactam)
4
Ethoxylated TMPTA oligomer (EO-TMPTA)
5
2,6-di-t-butylphenol (antioxidant)
6
Hexanediol diacrylate (HDDA)
7
Ethoxylated TMPTA oligomer (EO-TMPTA)
8
N-octylpyrrolidinone
9
Tripropylene glycol, diacrylate (TPGDA)
10
D-10 anthracene (internal standard)
11
Trimethylolpropanetriacrylate (TMPTA)
12
Benzyl, dimethyl ketal (BDK, UV-photoinitiator)
13
Ethoxylated TMPTA oligomer (EO-TMPTA)
14
n-c22 Docosane(internal standard)
39
Figure 16. Chromatograph of EB/UV curable packaging extraction
* Numbered compounds on the chromatograph are listed on Table 11.
** Chromatograph of experiment number 3-1 on Table 8. ; With agitation, 1 day, 10% ETOH, 40 ºC, 3mL/in² (agitation, extraction duration, food simulant, temperature, and solvent/surface ratio, respectively
40
3. Total migrants (ppb) of “EB/UV CURABLE” packaging system by conditions 3.1. Agitation variable Through the agitation variable test, holding other factors constant 1 day, 10% ETOH, 40 ºC , 3mL/in² (extraction duration, food simulant, temperature, and solvent/surface ratio respectively), the total migrant levels were 662.86 ppb with agitation and 558.94 ppb without agitation, respectively. As shown in Figure 17., the test with agitation extracted slightly more total extractables than without agitation.
Figure 17. Total migrant level of EB/UV curable packaging extraction by agitation
variable
Total Migrants (ppb)
ppb 800.00
662.86
700.00
558.94
600.00 500.00 400.00 300.00 200.00 100.00 0.00 with Agit.*
without Agit.
* 40 ºC data is duplicated from the Solvent Volume/Surface Area Ratio (mL/Inch²) variable experiment because of same parameter conditions.
41
3.2. Simulated Solvent variable Through the simulated solvent variable experiments for EB/UV curable packaging, the total migrant levels were 626.90 ppb with 10% EtOH, 4892.96 ppb with 95% EtOH, 582.35 ppb with 3% Acetic Acid in Water, and 556.17 ppb with Water, respectively. Those data showed that the solvent strength also had a significant effect on EB/UV curable packaging extraction. The simulated solvent 95% EtOH extracted about 8 times of migrants than the other solvents, with holding other parameters constant, 1 day, with agitation, 40 ºC , 3mL/in² (extraction duration, agitation, temperature, and solvent/surface ratio respectively).
Figure 18. Total migrant level of EB/UV curable packaging extraction by simulant variable
Total Migrants (ppb)
ppb 6000.00
4892.96
5000.00 4000.00 3000.00 2000.00 1000.00
626.90
582.35
556.17
3% Acetic Acid in Water
Water
0.00 10% ETOH
95% ETOH
42
3.3. Time variable Through the time variable tests, holding other factors constant - 10% ETOH, with agitation, 40 ºC , 3mL/in² (food simulant, agitation, temperature, and solvent/surface ratio respectively) -, the total migrant levels are 626.90 ppb with 1 day extraction, 721.55 ppb with 4 days, and 873.37 ppb with 10 days, respectively, as shown on Figure 19. As incubation time increased, the level of total migrants rose. 10 days experiment had about 1.4 times total migrant level than 1 day experiment. This is a slight difference. The migrant level of 10 days extraction is close to the recommended level for FDA test.
Figure 19. Total migrant level of EB/UV curable packaging extraction by time variable
Total Migrants (ppb) ppb 1000.00 873.37
900.00 800.00 700.00
721.55 626.90
600.00 500.00 400.00 300.00 200.00 100.00 0.00 24 Hours*
4 Days
10 Days
* “24 hours” data is duplicated from the Simulated Solvent Variable experiment (10% EtOH) because of same parameter conditions.
43
3.4. Temperature variable As shown on Figure 20., levels of total migrants of EB/UV curable packaging extraction increased progressively by temperature increment. With holding other variables were constant - 1 day, with agitation, 10% ETOH, 3mL/in² (extraction duration, agitation, food simulant, and solvent/surface ratio respectively)-, the total migrant levels are 478.81 ppb at 25 ºC, 626.90 ppb at 40 ºC, 745.08 ppb at 60 ºC, and 1066.73 ppb at 80 ºC, respectively.
Figure 20. Total migrant level of EB/UV curable packaging extraction by Temperature variable
Total Migrants (ppb)
ppb 1200.00
1066.73
1000.00 745.08
800.00 626.90 600.00
478.81
400.00 200.00 0.00 25 ℃
40 ℃ *
60 ℃
80 ℃
* 40 ºC data is duplicated from the Simulated Solvent Variable experiment because of same parameter conditions.
44
3.5. Solvent Volume/Surface Area Ratio (mL/Inch²) variable As shown on Figure 21., The ratio of solvent volume per surface area (mL/Inch²) variable experiments showed that total migrant levels of UV/EB cured printing extractables decreased on ppb (w/v) unit as the ratio increased. However, when the unit was normalized onto ng/cm², total migrant level of extractables increased gradually as the increment of the ratio, as shown on Figure 22.
Figure 21. Total migrant level of EB/UV curable packaging extraction by Solvent Volume/Surface Area Ratio (mL/Inch²) variable (ppb w/v unit)
Total Migrants (ppb)
ppb 1400.00 1205.02 1200.00 1000.00 800.00
662.86
600.00 437.25 400.00
377.03
200.00 0.00 1 mL/Inch²
3 mL/Inch²
5 mL/Inch²
10 mL/Inch²
45
Figure 22. Total migrant level of EB/UV curable packaging extraction by Solvent Volume/Surface Area Ratio (mL/Inch²) variable (ng/cm²)
Total Migrants (ng/cm²) ng/cm2 700.00 591.43
600.00 500.00 400.00
342.94
311.94 300.00 200.00
189.02
100.00 0.00 1 mL/Inch²
3 mL/Inch²
5 mL/Inch²
10 mL/Inch²
46
4.
Comparison of Soluble and Insoluble Extractables from UV/EB Cured
Packaging The comparisons between water soluble and insoluble migrants of UV/EB cured packaging extract experiment were performed in order to identify the differences of extractability by parameters. The water solubility of each extractable from UV/EB cured packaging is listed on Table 12. For the representatives of water soluble and insoluble compounds, caprolactam (CAS# 105-60-2) and 2,6-di-t-butylphenol (antioxidant) (CAS# 128-39-2, 19126-15-9 or 118-82-1) were chosen, respectively. Caprolactam is one of the highest water soluble compounds among the extractables. It has the water solubility of 820g/L at 20°C (Wikipedia, 2010). 2,6-di-t-butylphenol (antioxidant) (CAS# 128-39-2, 19126-15-9 or 118-82-1) is one of water insoluble extractables from UV/EB cured packaging extraction, distinctly. Although, both of water soluble and insoluble representatives - caprolactam and 2,6-di-t-butylphenol respectively - were extracted in only infinitesimal amount, which were less than FDA regulation -50 ppb w/v- for NonGRAS compound to become food additives, at almost all of our experiments, those migrants were still significant indicators for the extraction tests. It is because those compounds are of integral substances for UV/EB curable ink.
47
Table 12. Solubilities of migrants of UV/EB Curable packaging
CAS Number diethylene glycol monobutyl ether (Dowanol DB)
112-34-5
hydroquinone methyl ether (MEHQ inhibitor)
150-76-5
caprolactam
105-60-2
2,6-di-t-butylphenol (antioxidant)
128-39-2 19126-15-9 118-82-1
hexanediol diacrylate (HDDA)
Water Solubility
Other Solubility
Soluble, Miscible
Ether, Alcohol, Aceton, Benzene
Soluble, 40g/L (25℃) Highly Soluble, 820g/L (20℃)
(ANTIOXIDANT SK702)
13048-33-4 88250-32-2
Insoluble, NEGLIGIBLE
