§ 173.25 21 CFR Ch. I (4–1–09 Edition) ion exchange membranes intended for (2) Sulfonated anthracite coal meet- use in the treatment of bulk quantities ing the requirements of ASTM method of liquid food under the following pre- D388–38, Class I, Group 2, ‘‘Standard scribed conditions: Specifications for Classification of Coal (a) Identity. The membrane is a co- by Rank,’’ which is incorporated by polymer of ethanesulfonyl fluoride, 2- reference. Copies are available from [1-[difluoro-[(trifluoro- University Microfilms International, ethenyl)oxy]methyl]-1,2,2,2-tetrafluoro- 300 N. Zeeb Rd., Ann Arbor, MI 48106, or ethoxy]-1,1,2,2,-tetrafluoro-, with tetra- available for inspection at the National fluoroethylene that has been subse- Archives and Records Administration quently treated to hydrolyze the (NARA). For information on the avail- sulfonyl fluoride group to the sulfonic ability of this material at NARA, call acid. The Chemical Abstracts Service 202–741–6030, or go to: http:// name of this polymer is ethanesulfonic www.archives.gov/federallregister/ acid, 2-[1-[difluoro-[(trifluoro- codeloflfederallregulations/ ethenyl)oxy]methyl]-1,2,2,2-tetrafluoro- ibrllocations.html. ethoxy]-1,1,2,2,-tetrafluoro-, polymer (3) Sulfite-modified cross-linked phe- with tetrafluoroethane (CAS Reg. No. nol-formaldehyde, with modification 31175–20–9). resulting in sulfonic acid groups on (b) Optional adjuvant substances. The side chains. basic polymer identified in paragraph (4) Methacrylic acid-divinylbenzene (a) of this section may contain optional copolymer. adjuvant substances required in the (5) Cross-linked polystyrene, first production of such basic polymer. chloromethylated then aminated with These optional adjuvant substances trimethylamine, dimethylamine, di- may include substances used in accord- ethylenetriamine, or dimethylethanol- ance with § 174.5 of this chapter. amine. (c) Conditions of use. (1) (6) Diethylenetriamine, triethylene- Perfluorinated ion exchange mem- tetramine, or tetraethylenepentamine branes described in paragraph (a) of cross-linked with epichlorohydrin. this section may be used in contact (7) Cross-linked phenol-formaldehyde with all types of liquid foods at tem- activated with one or both of the fol- peratures not exceeding 70° (158 °F). lowing: Triethylene tetramine and (2) Maximum thickness of the copoly- tetraethylenepentamine. mer membrane is 0.007 inch (0.017 centi- (8) Reaction resin of formaldehyde, meter). acetone, and tetraethylenepentamine. (3) Perfluorinated ion exchange mem- (9) Completely hydrolyzed copoly- branes shall be maintained in a sani- mers of methyl acrylate and tary manner in accordance with cur- divinylbenzene. rent good manufacturing practice so as (10) Completely hydrolyzed to prevent microbial adulteration of terpolymers of methyl acrylate, food. divinylbenzene, and acrylonitrile. (4) To assure their safe use, (11) Sulfonated terpolymers of sty- perfluorinated ionomer membranes rene, divinylbenzene, and acrylonitrile shall be thoroughly cleaned prior to or methyl acrylate. their first use in accordance with cur- (12) Methyl acrylate-divinylbenzene rent good manufacturing practice. copolymer containing not less than 2 percent by weight of divinylbenzene, [59 FR 15623, Apr. 4, 1994] aminolyzed with dimethylaminopro- pylamine. § 173.25 Ion-exchange resins. (13) Methyl acrylate-divinylbenzene Ion-exchange resins may be safely copolymer containing not less than 3.5 used in the treatment of food under the percent by weight of divinylbenzene, following prescribed conditions: aminolyzed with dimethylaminopro- (a) The ion-exchange resins are pre- pylamine. pared in appropriate physical form, and (14) Epichlorohydrin cross-linked consist of one or more of the following: with ammonia. (1) Sulfonated copolymer of styrene (15) Sulfonated tetrapolymer of sty- and divinylbenzene. rene, divinylbenzene, acrylonitrile, and 124 VerDate Nov<24>2008 14:38 May 05, 2009 Jkt 217067 PO 00000 Frm 00134 Fmt 8010 Sfmt 8010 Y:\SGML\217067.XXX 217067 cprice-sewell on PRODPC61 with CFR Food and Drug Administration, HHS § 173.25 methyl acrylate derived from a mix- (b)(1) of this section, the ion-exchange ture of monomers containing not more resin identified in paragraph (a)(13) of than a total of 2 percent by weight of this section is used only in accordance acrylonitrile and methyl acrylate. with paragraph (b)(2) of this section, (16) Methyl acrylate-divinylbenzene- the resin identified in paragraph (a)(16) diethylene glycol divinyl ether of this section is used only in accord- terpolymer containing not less than 3.5 ance with paragraph (b)(1) or (b)(2) of percent by weight of divinylbenzene this section, the ion-exchange resin and not more than 0.6 percent by identified in paragraph (a)(17) of this weight of diethylene glycol divinyl section is used only in accordance with ether, aminolyzed with dimethyl- paragraph (b)(3) of this section, the aminopropylamine. ion-exchange resin identified in para- (17) Styrene-divinylbenzene cross- graph (a)(18) of this section is used only linked copolymer, first in accordance with paragraph (b)(4) of chloromethylated then aminated with this section, and the ion-exchange dimethylamine and oxidized with hy- resin identified in paragraph (a)(20) of drogen peroxide whereby the resin con- this section is used only in accordance tains not more than 15 percent by with paragraphs (b)(5) and (d) of this weight of vinyl N,N-dimethylbenzyl- section. amine-N-oxide and not more than 6.5 (1) The ion-exchange resins identified percent by weight of nitrogen. in paragraphs (a) (12) and (16) of this (18) Methyl acrylate-divinylbenzene- section are used to treat water for use diethylene glycol divinyl ether in the manufacture of distilled alco- terpolymer containing not less than 7 holic beverages, subject to the fol- percent by weight of divinylbenzene lowing conditions: and not more than 2.3 percent by (i) The water is subjected to treat- weight of diethylene glycol divinyl ment through a mixed bed consisting of ether, aminolyzed with dimethyl- one of the resins identified in para- aminopropylamine and quaternized graph (a) (12) or (16) of this section and with methyl chloride. one of the strongly acidic cation-ex- (19) Epichlorohydrin cross-linked change resins in the hydrogen form with ammonia and then quaternized identified in paragraphs (a) (1), (2), and with methyl chloride to contain not (11) of this section; or more than 18 percent strong base ca- (ii) The water is first subjected to pacity by weight of total exchange ca- one of the resins identified in para- pacity [Chemical Abstracts Service graph (a) (12) or (16) of this section and name: Oxirane (chloromethyl)-, poly- is subsequently subjected to treatment mer with ammonia, reaction product through a bed of activated carbon or with chloromethane; CAS Reg. No. one of the strongly acidic cation-ex- 68036–99–7]. change resins in the hydrogen form (20) Regenerated cellulose, cross- identified in paragraphs (a) (1), (2), and linked and alkylated with epichloro- (11) of this section. hydrin and propylene oxide, then sulfo- (iii) The temperature of the water nated whereby the amount of epi- passing through the resin beds identi- chlorohydrin plus propylene oxide em- fied in paragraphs (b)(1) (i) and (ii) of ployed does not exceed 250 percent by this section is maintained at 30 °C or weight of the starting quantity of cel- less, and the flow rate of the water lulose. passing through the beds is not less (b) Ion-exchange resins are used in than 2 gallons per cubic foot per the purification of foods, including po- minute. table water, to remove undesirable ions (iv) The ion-exchange resins identi- or to replace less desirable ions with fied in paragraph (a) (12) or (16) of this one or more of the following: bicarbon- section are exempted from the require- ate, calcium, carbonate, chloride, hy- ments of paragraph (c)(4) of this sec- drogen, hydroxyl, magnesium, potas- tion, but the strongly acidic cation-ex- sium, sodium, and sulfate except that: change resins referred to in paragraphs The ion-exchange resin identified in (b)(1) (i) and (ii) of this section used in paragraph (a)(12) of this section is used the process meet the requirements of only in accordance with paragraph paragraph (c)(4) of this section, except 125 VerDate Nov<24>2008 14:38 May 05, 2009 Jkt 217067 PO 00000 Frm 00135 Fmt 8010 Sfmt 8010 Y:\SGML\217067.XXX 217067 cprice-sewell on PRODPC61 with CFR § 173.25 21 CFR Ch. I (4–1–09 Edition) for the exemption described in para- Paint Branch Pkwy., College Park, MD graph (d) of this section. 20740, or may be examined at the Cen- (2) The ion-exchange resins identified ter for Food Safety and Applied Nutri- in paragraphs (a) (13) and (16) of this tion’s Library, 5100 Paint Branch section are used to treat water and Pkwy., College Park, MD 20740, or at aqueous food only of the types identi- the National Archives and Records Ad- fied under Categories I, II, and VI-B in ministration (NARA). For information table 1 of § 176.170(c) of this chapter: on the availability of this material at Provided, That the temperature of the NARA, call 202–741–6030, or go to: http:// water or food passing through the resin www.archives.gov/federallregister/ beds is maintained at 50 °C or less and codeloflfederallregulations/ the flow rate of the water or food pass- ibrllocations.html. ing through the beds is not less than 0.5 (3) The ion-exchange resin identified gallon per cubic foot per minute. in paragraph (a)(17) of this section is (i) The