Examination of styrene-divinylbenzene ion exchange resins, used in contact with food, for potential migrants John Andrew Sidwell, Bryan Willoughby To cite this version: John Andrew Sidwell, Bryan Willoughby. Examination of styrene-divinylbenzene ion exchange resins, used in contact with food, for potential migrants. Food Additives and Contaminants, 2006, 23 (07), pp.726-737. 10.1080/02652030600576189. hal-00577289 HAL Id: hal-00577289 https://hal.archives-ouvertes.fr/hal-00577289 Submitted on 17 Mar 2011 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. 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Food Additives and Contaminants For Peer Review Only Examination of styrene-divinylbenzene ion exchange resins, used in contact with food, for potential migrants Journal: Food Additives and Contaminants Manuscript ID: TFAC-2005-268.R1 Manuscript Type: Original Research Paper Date Submitted by the 09-Jan-2006 Author: Complete List of Authors: Sidwell, John; Rapra Technology Ltd., Analytical Willoughby, Bryan; Rapra Technology Ltd Methods/Techniques: GC/MS, LC/MS Additives/Contaminants: Migration, Food contact materials Food Types: http://mc.manuscriptcentral.com/tfac Email: [email protected] Page 1 of 35 Food Additives and Contaminants 1 2 3 4 Examination of styrene-divinylbenzene ion exchange resins, 5 6 used in contact with food, for potential migrants 7 8 9 10 11 JOHN A. SIDWELL and BRYAN G. WILLOUGHBY 12 13 14 For Peer Review Only 15 Rapra Technology Ltd, Shawbury, Shrewsbury, Shropshire, SY4 4NR, UK 16 17 18 19 20 Abstract 21 22 The nature of extractable substances from five types of styrene-divinylbenzene ion 23 24 exchange resins used in the preparation of foodstuffs was investigated. Strong acid 25 26 cation resins, strong and weak base anion resins and an active carbon replacement 27 28 resin were examined. These resins are used for a variety of purposes including water 29 30 31 softening, decalcification of sugar syrups, demineralisation, removal of nitrate ions from 32 33 water and decolourisation. Analysis was carried out using electrospray LC-MS and GC- 34 35 MS based methodologies. Extractable substances from new resins were identified as 36 37 mainly being by-products of the resin manufacturing process. Levels of extractable 38 39 substances decreased with washing. 40 41 42 43 44 Keywords: Ion exchange resin, food contact, styrene-divinyl benzene resin, extractable 45 46 substances, LC-MS, thermal desorption GC-MS, two-dimensional gas chromatography 47 48 time of flight mass spectrometry (GCxGC-TOF-MS) 49 50 51 52 53 54 55 56 57 58 59 60 1 http://mc.manuscriptcentral.com/tfac Email: [email protected] Food Additives and Contaminants Page 2 of 35 1 2 3 Introduction 4 5 6 7 8 Ion exchange resins are very high surface area materials that have the potential to 9 10 contaminate food. Annex 1 to EC Regulation No 1935/2004 (EC. 2004), the revised and 11 12 up-dated food-contact framework regulation, now includes ion exchange resins in the list 13 14 of groups Forof materials Peer and articles Review that may be covered Only by specific harmonised 15 16 measures. 17 18 19 20 21 A Council of Europe (1997) resolution on ion exchange resins (AP 97/1) includes an 22 23 inventory list of substances used in the manufacture of ion exchange resins and a 24 25 migration limit of 1mg/L total organic carbon in the 5 th bed volume (water) rinse solution. 26 27 In the USA, a list of ion exchange resins authorised for food-contact use, together with 28 29 some restrictions, are given in the FDA regulations Title 21, Section 173.25. A number of 30 31 32 successful food contact notifications have been granted for applications of ion exchange 33 34 resins with specific functionality. Miers (1995) has reviewed US regulations on ion 35 36 exchange resins. Utsunomiya (1995) has reviewed requirements in Japan. 37 38 39 40 In this paper we report the chemical nature, extractability and source of potential 41 42 extractable substances from a range of styrene divinylbenzene ion exchange resins 43 44 45 used in contact with food, as received from the manufacturer. No pre-washing of resins 46 47 as would be recommended before first-use, was undertaken. 48 49 50 51 Conceptually, ion exchange materials are insoluble acids or bases which, when 52 53 converted to salts, remain insoluble. Cation exchange materials contain fixed 54 55 electronegative charges (associated with counter ions), e.g. RSO −Na +, and anion 56 3 57 + − 58 exchange materials analogously have fixed electropositive charges, e.g. RN Me 3Cl . 59 60 2 http://mc.manuscriptcentral.com/tfac Email: [email protected] Page 3 of 35 Food Additives and Contaminants 1 2 3 Strong-acid cation exchange materials are usually based on sulphonic acids. Strong- 4 5 6 base anion exchange materials may be quaternary ammonium hydrochlorides and 7 8 weaker base types may be the tertiary amines themselves. Most ion exchange resins 9 10 can be regenerated with appropriate counter ions. It is not uncommon for resin beds to 11 12 be continually used and regenerated over periods of months/years before total resin 13 14 replacement.For Some resins Peer are operated Review at elevated temperatures Only e.g. 70 oC. 15 16 17 18 19 The main applications of ion exchange resins in food processing include the treatment of 20 21 water added to or used with food products, sugar decolourisation/demineralisation, 22 23 isolation of proteins and enzymes from milk products and wine/spirit treatments. Of these 24 25 applications, treatment of water for use with food products is the largest application. 26 27 28 29 Potential migrants from ion exchange resins include both organic and inorganic species. 30 31 32 The latter includes the inorganic ions involved in the process of ion exchange or of resin 33 34 regeneration. The type and amount of these will be dependent on the resin types used 35 36 and the manner and sequence of operation. Given the nature of these operations, and 37 38 the copious use of water, it is likely that any problems from ionic impurities will be 39 40 transient ones. 41 42 43 44 45 Organic contaminants are potentially more persistent. Organic contaminants in output 46 47 streams will include those input contaminants incompletely removed by the resin and 48 49 those contributed by the resin itself. The latter potentially includes: input contaminants 50 51 accumulating on the resin and being re-released under breakthrough conditions, 52 53 products of thermal or oxidative oxidation of the resin and residues of the chemistry of 54 55 manufacture of the resin. 56 57 58 59 60 3 http://mc.manuscriptcentral.com/tfac Email: [email protected] Food Additives and Contaminants Page 4 of 35 1 2 3 Whilst the first two above are artefacts of the process and the conditions of operation, 4 5 6 and are amenable to control in a properly run process, the third is outside the control of 7 8 the process operators. Studies of water deionisation for the electronics industry (Gottlieb 9 10 and Meyers, 2000) have found that this third source (residues of manufacture) is the 11 12 largest source of organic impurities. Such leachable organic impurities are at their 13 14 highest levelFor in brand-new Peer resins, and Review gradually rinse out with Only time. 15 16 17 18 19 Materials and Methods 20 21 The ion exchange resins examined were suitably functionalised styrene-divinylbenzene 22 23 resins. Cation exchange styrene-divinylbenzene resins are acid or acid-salt 24 25 functionalised. For these resins, the initial step is sulphonation of the aromatic ring, e.g.: 26 27 ∼C6H5 + SO 3 → ∼C6H4SO 3H 28 29 30 Styrene-divinylbenzene anion exchange resins are obtained via chloromethylation. The 31 32 reaction is complex and may be represented in a number of ways. Conceptually it is a 33 34 reaction of chloromethyl ether. Chloromethyl ether is created in situ by formaldehyde/HCl 35 36 reaction. 37 38 ∼C6H5 + CH 3OCH 2Cl → ∼C6H4CH 2Cl + CH 3OH 39 40 41 This is then followed by amination: 42 43 ∼C6H4CH 2Cl + NHR 2 → ∼C6H4CH 2NHR 2 Cl 44 45 ∼C6H4CH 2Cl + NR 3 → ∼C6H4CH 2NR 3 Cl 46 47 Resins were analysed as supplied by the manufacturer. 48 49 50 51 52 53 54 55 56 57 58 59 60 4 http://mc.manuscriptcentral.com/tfac Email: [email protected] Page 5 of 35 Food Additives and Contaminants 1 2 3 Strong acid cation exchange resins 4 5 6 Two styrene divinyl benzene cation resins with sulphonate functionality (Resins A and B) 7 8 were analysed. Resin A complied with European standards for use in potable water 9 10 applications and was in compliance with the U.S. Food and Drug Administration Code of 11 12 Federal Regulations section 21, paragraph 173.25, for use in the treatment of foods for 13 14 human consumption.For PeerThis gel type Reviewresin is used for water Only softening and has ~10% 15 16 cross-linking. Resin B was a macroporous cation exchange resin. It is used in the 17 18 19 decalcification of sugar syrups during isolation of sugar from sugar beet.