Primary Aromatic Amines

Transcription

1 Dr. Dennis Bankmann and Dr. Roberto Pela July 2017 Primary Aromatic Amines Globally relevant content

2 02/11 Primary Aromatic Amines Relevant Legislation (EC) No. 1935/2004, recital 3: [ ] any material or article intended to come into contact directly or indirectly with food must be sufficiently inert to preclude substances from being transferred to food in quantities large enough to endanger human health [ ] (EU) No. 10/2011, Annex II.2: Plastic materials and articles shall not release primary aromatic amines, excluding those appearing in Table 1 of Annex I, in a detectable quantity into food or food simulant. The detection limit is 0.01 mg of substance per kg of food or food simulant. The detection limit applies to the sum of primary aromatic amines released. Swiss Verordnung des EDI über Bedarfsgegenstände (SR ), Annex 1 Primary aromatic amines (those listed in the regulation excepted) may not migrate in detectable quantities. Detection limit: 0.01 mg/kg food or simulant incl. analytical tolerance Turkish codex for plastic materials and articles in food contact No. 2013/34, Appendix 2 Equivalent requirements to (EU) No. 10/2011 Mercosur GMC/RES No 40/15: Reglamento Técnico sobre materiales, envases y equipamientos celulósicos destinados a estar en contacto con alimentos Primary aromatic amines from dyes/colorants must not be released. Detection limit is set to 0.1 mg/kg of paper Indian Standard IS 9833:2014: List of Pigments & Colorants for Use in Plastics in Contact with Foodstuffs, Pharmaceuticals & Drinking Water Limits maximum content of PAA in pigments What are Aromatic Amines? The term Primary aromatic amine (PAA) refers to certain chemical substances from the wider chemical group of amines which notably carry a so-called aromatic ring. They are used industrially as precursors in the manufacture of certain pigments and polymers. A number of PAA have been identified as human carcinogens, i.e. understood to have the potential to cause cancer in humans. Hence, incorporation of any measurable quantity of this group of chemicals has to be avoided. A broad discussion around the topic of PAA has existed for several decades and still continues to this day with current focus on defining the most appropriate exposure limits (cf. BfR Opinion No 021/2014). Consequently, in many countries across the globe, legislators have introduced limits regarding the migration of aromatic amines from food contact materials into food (see box). It can be assumed that eventually, there will be restrictions in place globally as more and more countries recognize the importance of regulating these substances.

3 03/11 Primary Aromatic Amines The Reasons for the Occurrence of Aromatic Amines in Flexible Packaging H 2 N H 2 N CH 3 NH 2 H 3 C NH 2 2,4-Diaminotoluene 2,6-Diaminotoluene NH 2 H 2 N NH 2 NH 2 Methylenediphenyl-4,4 -diamine Methylenediphenyl-2,2 -diamine NH 2 NH 2 Methylenediphenyl-2,4 -diamine Primary aromatic amines are not present as intended components in any kind of packaging material. They can occur however, and if they do, it is because they are precursors, impurities or decomposition products of certain packaging components. The two notable sources are pigments and polyurethane based components in the packaging. The BfR FAQ of 28 August 2014 gives a good summary of the situation regarding ink pigments. Polyurethane materials, on the other side, can be found in inks, coatings and laminating adhesives and will be discussed here. Polyurethane based adhesives do not contain aromatic amines as part of the formulation. In fact, aromatic amines could not exist in the NCO component of polyurethane adhesives as they would react immediately. PAA can be formed, however, from certain isocyanate monomers which are present in most polyurethane adhesives in the uncured state. Importantly, the migration of PAA into food can therefore only occur if free isocyanate monomer is present at the time when food is brought into contact with the packaging. If this occurs, the moisture present in nearly any type of food and the residual isocyanates react to form PAA which can transfer into the food and can persist there until consumption. In fully cured adhesives designed for food contact applications, the amounts of residual isocyanate monomer, if present at all, are so low that they are nondetectable and so is the amount of PAA. These adhesives can be used very safely. It is however of the highest importance that polyurethane adhesives are given sufficient time to cure before the packaging material is used in the packaging process.

4 04/11 Primary Aromatic Amines In practice, the required curing time of the adhesive should be assessed on the actual laminate structure since the other components such as films and inks can influence the curing behavior of an adhesive. A typical approach is to check over the course of several days the amount of PAA that can migrate from a sample of laminate. This data series can be visualized as a so called PAA decay curve (Figure 1). This curve will, if the adhesive is suitable for use in food packaging, drop below the detection limit for PAA after a few days. The point in time at which no PAA are detectable anymore is the minimum cure time of the adhesive with respect to food safety under the given conditions. Figure 2 shows an example, illustrating a retortable packaging, in which the amount of extractable PAA drops below the 10 ppb limit after 5 days and below the detection limit of the used test method of 1.5 ppb after 7 days. Whilst the laminate would be safe for use in ambient temperatures, it is not suitable for retorted food as evident from the high amount of PAA detectable after the heat treatment. For this reason, a suitable adhesive, specifically designed for high temperature applications, needs to be chosen instead. Figure 2 Formation of PAA under high temperature processing. Extracted PAA [ppb] Besides the importance of allowing enough time for the adhesive to cure, it has to be considered that there is a second pathway to the formation of PAA from polyurethane materials: the cure mechanism of polyurethane polymers can be reversed at high temperatures, i.e. polyurethanes can partially decompose under thermal stress. At temperatures above 100 C, depending on actual temperature and duration, small amounts of isocyanate monomers can be liberated from the fully cured polyurethane polymer. If this happens in the presence of sufficient moisture, i.e. in a package already filled with food, PAA will be formed from the liberated isocyanates and can migrate into the food. It is therefore important in the case of high temperature applications such as pasteurized and retorted food as well as ovenable packaging to ensure the absence of PAA not only through sufficient curing time of the adhesive but also by testing under actual conditions of use <1.5 <1.5 1d 2d 5d 7d 14d 14d+retort curing time Figure 1 Decay of PAA migration during adhesive cure. Extracted PAA [ppb] from this point on, the laminate is safe for filling with food Detection limit curing time / days

5 05/11 Primary Aromatic Amines Ensuring Compliance: Testing Laminates for PAA To ensure safe and compliant laminated packaging materials, it is important to validate any newly developed packaging by a practical test to prove the absence of migration of PAA. Testing is required for any package in which, based on the component suppliers documentation, there is a possibility that PAA can be formed. This test should be performed both after the intended curing time as well as under conditions of use. There are two principal methods to test for PAA migration. The more common method is the so called photometric test, a method based on a German standard for consumer goods but applied to flexible packaging. This method allows for a fast and reliable determination of aromatic amines in many structures and is an excellent tool for quality control. Henkel believes in the importance of training and knowledge transfer along the value chain as an integral element of food safety and has helped many customers establish this method in their QC laboratory. The second, more sensitive and more powerful method is called the specific or HPLC method. It is an especially powerful tool in the diagnosis of complex packaging and for validating the safety of packaging for high temperature applications. The HPLC method requires a higher investment as well as maintenance and is commonly performed at institutes. Henkel s analytical center has been a pioneer in this method of testing and still offers it routinely today. Figure 3 PAA detection methods compared. Photometric Method Fast Low cost Good screening method False positives possible* Limited sensitivity Does not distinguish between different PAAs Used at Henkel to measure PAA decay curves Good choice for QC * Notably, heat treated packaging can show false positives. HPLC Method Excellent sensitivity Almost no interferences* Distinguishes different PAAs Can be automated Higher cost and upkeep Used at Henkel when developing new adhesives & troubleshooting Ideal for package development * Certain simulants can cause false negatives. This is material intrinsic and not detection method related.

6 06/11 Primary Aromatic Amines Testing Laminates for PAA: Photometric Method The following sections describe how to prepare extracts for the photometric analytical method, and the calculations required to determine the actual migration of PAA in the real packaging size. Section 1: Sample preparation and migration procedure Step 1: Unwind 10 layers from the reel and cut 4 samples of x mm from the middle of the width. Keep at least 3 cm away from the edge of the reel. Remove enough laminate to make up to 3 pouches Unwind 10 times before sampling! Step 2: Make pouches from the cutouts by heat sealing (size described in ). Fill each pouch with 100 ml of test simulant (3% acetic acid). Close the pouch by heat sealing mm mm Make pouch, fill with simulant Step 3: Allow PAA to migrate by heating the pouches in an oven to 70 C for 2 hours (flip the pouches after 1 hour at 70 C). Store in specified conditions Step 4: Cut open each pouch on one edge, pour the liquid into a brown glass bottle ( ). Add the required reagents for the derivatization of amines before proceeding with the instrumental analysis. Store the samples away from heat and light. Recover simulant and add reagents Section 2: Analysis using the photometric method The photometric test gives the concentration of PAA in µg released into 100 ml of simulant. The calculations to obtain the actual amount of PAA considering the actual packaging geometry is: PAA (µg/kg food) = (c x S x 0.25 / f) x 5 # c = concentration of PAA measured by the spectrophotometer (µg/100 ml) S = actual packaging size (dm²) f = actual food quantity (kg) # Factor 5 = a safety factor of 5 is applied in this calculation to account for different response factors of different types of PAA. You can also use our free online calculation tool to conveniently perform the required calculations:

7 07/11 Primary Aromatic Amines Testing Laminates for PAA: HPLC Method The following sections describe how to prepare extracts for the HPLC analytical method, and the calculations required to determine the actual migration of PAA in the real packaging size. Section 1: Sample preparation and migration procedure Step 1: Unwind 10 layers from the reel and cut 3 samples of x mm from the middle of the width. Keep at least 3 cm away from the edge of the reel. Remove enough laminate to make up to 3 pouches Unwind 10 times before sampling! Step 2: Make pouches from the cutouts by heat sealing (size described in ). Fill each pouch with 100 ml of test simulant (3% acetic acid). Close the pouch by heat sealing mm mm Make pouch, fill with simulant Step 3: Allow PAA to migrate by heating the pouches in an oven to 70 C for 2 hours (flip the pouches after 1 hour at 70 C). Store in specified conditions Step 4: Cut open each pouch on one edge, and pour the liquid into a glass bottle ( ). Samples are now ready for the chromatographic analysis. Recover simulant Section 2: Analysis using HPLC The HPLC analysis gives the concentration of PAA in µg/l. The calculations to obtain the actual amount of PAA considering your real package size is: PAA (µg/kg food) = c x S x / f c = concentration of PAA measured by the spectrophotometer (µg/l) S = actual packaging size (dm²) f = actual food quantity (kg) You can also use our free online calculation tool to conveniently perform the required calculations:

8 08/11 Primary Aromatic Amines Considerations to Minimize the Risk of Aromatic Amine Migration 1. Before the production of a new packaging structure, a validation of the time for the adhesive to reach full cure is required. Changes to the structure or the adhesive require revalidation of the cure time. 2. The choice of packaging film as well as the other components of a package can influence the time required for the adhesive to cure fully. Notable, polyamide films may increase the cure time by several days. 3. Consistent production conditions are important for consistent cure. Important influences are temperature and humidity. Temperatures of stored reels should not drop below 18 C of any time during cure. If temperature and humidity vary substantially over the course of a year, cure times should be set up so that even under the most adverse conditions of a dry, cold winter, full cure is achieved reliably. 4. Fast curing adhesives substantially reduce the required storage time and offer the highest intrinsic safety. Henkel offers fast cure / smart cure adhesives as well as low monomer and ultra low monomer adhesives. These technologies can allow for cure times of less than one day on many substrates as far as the migration of PAA is concerned, and less than three days on many polyamide containing structures. 5. PAA can also be formed through thermal decomposition of polyurethane adhesives. This is a factor important to consider in retort and ovenable applications. Only specially designed adhesives should be used for inner layer applications under high temperature. The intrinsically safest option is the use of an adhesive based solely on aliphatic isocyanates which cannot form PAA regardless of the temperature.

9 09/11 Primary Aromatic Amines Henkel Offers with Highest Safety Towards PAA Migration Room temperature to pasteurization Fast cure solvent-free and solvent-based adhesives Ultra low monomer solvent-free adhesives Ultra low monomer solvent-based adhesives FastOne technology (NCO free) All applications inclusive retort and ovenable Aliphatic solvent-free adhesives Aliphatic solvent-based adhesives Water based adhesives Figure 5 PAA decay curves of different technologies. Extracted PAA [ppb] Ultra low monomer solvent-free Low monomer solvent-based Smart cure solvent-free Conventional solvent-based Conventional solvent-free Ultra low monomer solvent-based Aliphatic adhesives Isocyanate free adhesives Detection limit curing time / days

10 10/11 Primary Aromatic Amines Key Take Aways Aromatic amine migration is one of the most important aspects related to the safe use of polyurethane laminating adhesives as well as other polyurethane based packaging components Aromatic amines need to be monitored as part of good manufacturing practice Henkel offers a range of solutions to minimize the risk of formation of aromatic amines and to optimize the curing times of laminating adhesives. Aliphatic solutions for retortable and ovenable packaging are completely free of any risk associated with PAA Literature and useful links European Legislation offered in 24 languages Resolutions of the Mercosur Common Market Group BfR photometric method Official collection of analytical methods of BVL (Federal Office of Consumer Protection and Food Safety) according to 64 LFGB (former 35 LMBG), method no. L Questions and Answers on Primary Aromatic Amines in Printing Inks for Paper Napkins and Food Packaging BfR FAQ of 28 August 2014 Primary aromatic amines from printed food contact materials such as napkins or bakery bags BfR Opinion No 021/2014

11 11/11 Primary Aromatic Amines Meet Your Experts Dr. Dennis Bankmann, a physico-organic chemist by training, is responsible for the development of LOCTITE LIOFOL products in Europe. Since 2007, he has worked on research projects for a number of different adhesive sectors before focusing exclusively on adhesives for flexible packaging and food contact materials. He and his team bring deep chemical knowledge to the interface between raw material suppliers, production, analytics and product safety. Dr. Roberto Pela, an organic chemist by training, joined Henkel in 2010 and worked for a number of years as a Technical Manager in the R&D department, developing new laminating adhesives for the food packaging market with a strong focus on improved safety. In 2016, he became a Technical Service Manager for LOCTITE LIOFOL in Flexible Laminates Europe. In his current role, he supports customers by providing extensive knowledge in laminating adhesives, lamination techniques, and general processes in the food packaging business. Further information Visit the Food Safe Packaging Premium Area offering webinars, white papers, FAQs, videos and more: Contact us! Many options available. Webinars Our webinars allow you to directly communicate with our Henkel food safety experts. Check our website for the dates of upcoming webinars. Migration Testing in Flexible Packaging Points to consider Primary Aromatic Amines Everything you need to know Aliphatic Laminating Adhesives Safe and highly productive solutions for retortable packaging Henkel AG & Co. KGaA Düsseldorf, Germany The information provided herein, especially recommendations for the usage and the application of our products, is based upon our knowledge and experience. Due to different materials used as well as to varying working conditions beyond our control we strictly recommend to carry out intensive trials to test the suitability of our products with regard to the required processes and applications. We do not accept any liability with regard to the above information or with regard to any verbal recommendation, except for cases where we are liable of gross negligence or false intention. The information is protected by copyright. In particular, any reproductions, adaptations, translations, storage and processing in other media, including storage or processing by electronic means, enjoy copyright protection. Any exploitation in whole or in part thereof shall require the prior written consent of Henkel AG & Co. KGaA. Except as otherwise noted, all marks used in this document are trademarks and/or registered trademarks of Henkel and/or its affiliates in the US, Germany, and elsewhere. Henkel AG & Co. KGaA, 7/2017