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173.25 Ion-exchange resins.

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[Code of Federal Regulations]
[Title 21, Volume 3]
[Revised as of April 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 21CFR173.25]

[Page 122-125]
 
                        TITLE 21--FOOD AND DRUGS
 
CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN 
                          SERVICES (CONTINUED)
 
PART 173_SECONDARY DIRECT FOOD ADDITIVES PERMITTED IN FOOD FOR HUMAN 
CONSUMPTION--Table of Contents
 
  Subpart A_Polymer Substances and Polymer Adjuvants for Food Treatment
 
Sec.  173.25  Ion-exchange resins.

    Ion-exchange resins may be safely used in the treatment of food 
under the following prescribed conditions:
    (a) The ion-exchange resins are prepared in appropriate physical 
form, and consist of one or more of the following:
    (1) Sulfonated copolymer of styrene and divinylbenzene.
    (2) Sulfonated anthracite coal meeting the requirements of ASTM 
method D388-38, Class I, Group 2, ``Standard Specifications for 
Classification of Coal by Rank,'' which is incorporated by reference. 
Copies are available from University Microfilms International, 300 N. 
Zeeb Rd., Ann Arbor, MI 48106, or available for inspection at the 
National Archives and Records Administration (NARA). For information on 
the availability of this material at NARA, call 202-741-6030, or go to: 
http://www.archives.gov/federal--register/code--of--federal--
regulations/ibr--locations.html.
    (3) Sulfite-modified cross-linked phenol-formaldehyde, with 
modification resulting in sulfonic acid groups on side chains.
    (4) Methacrylic acid-divinylbenzene copolymer.
    (5) Cross-linked polystyrene, first chloromethylated then aminated 
with trimethylamine, dimethylamine, di-ethylenetriamine, or 
dimethylethanol-amine.
    (6) Diethylenetriamine, triethylene-tetramine, or 
tetraethylenepentamine cross-linked with epichlorohydrin.
    (7) Cross-linked phenol-formaldehyde activated with one or both of 
the following: Triethylene tetramine and tetraethylenepentamine.
    (8) Reaction resin of formaldehyde, acetone, and 
tetraethylenepentamine.
    (9) Completely hydrolyzed copolymers of methyl acrylate and 
divinylbenzene.
    (10) Completely hydrolyzed terpolymers of methyl acrylate, 
divinylbenzene, and acrylonitrile.
    (11) Sulfonated terpolymers of styrene, divinylbenzene, and 
acrylonitrile or methyl acrylate.
    (12) Methyl acrylate-divinylbenzene copolymer containing not less 
than 2 percent by weight of divinylbenzene, aminolyzed with 
dimethylaminopro-pylamine.
    (13) Methyl acrylate-divinylbenzene copolymer containing not less 
than 3.5 percent by weight of divinylbenzene, aminolyzed with 
dimethylaminopro-pylamine.
    (14) Epichlorohydrin cross-linked with ammonia.
    (15) Sulfonated tetrapolymer of styrene, divinylbenzene, 
acrylonitrile, and methyl acrylate derived from a mixture of monomers 
containing not more than a total of 2 percent by weight of acrylonitrile 
and methyl acrylate.
    (16) Methyl acrylate-divinyl benzene di ethylene glycol divinyl 
ether terpolymer containing not less than 3.5 percent by weight of di 
vinyl benzene and not more than 0.6 percent by weight of di ethylene 
glycol divinyl ether, aminolyzed with di methyl amino propyl amine.
    (17) Styrene-divinylbenzene cross-linked copolymer, first 
chloromethylated then aminated with dimethylamine and oxidized with 
hydrogen peroxide whereby the resin contains not more than 15 percent by 
weight of vinyl N,N-di methyl benzyl amine-N-oxide and not more than 6.5 
percent by weight of nitrogen.
    (18) Methyl acrylate-divinylbenzene-diethylene glycol divinyl ether 
terpolymer containing not less than 7 percent by weight of 
divinylbenzene

[[Page 123]]

and not more than 2.3 percent by weight of diethylene glycol divinyl 
ether, aminolyzed with di methyl amino propyl amine and quaternized with 
methyl chloride.
    (19) Epichlorohydrin cross-linked with ammonia and then quaternized 
with methyl chloride to contain not more than 18 percent strong base 
capacity by weight of total exchange capacity [Chemical Abstracts 
Service name: Oxirane (chloromethyl)-, polymer with ammonia, reaction 
product with chloromethane; CAS Reg. No. 68036-99-7].
    (20) Regenerated cellulose, cross-linked and alkylated with epi 
chloro hydrin and propylene oxide, then sulfonated whereby the amount of 
epi chloro hydrin plus propylene oxide employed does not exceed 250 
percent by weight of the starting quantity of cellulose.
    (b) Ion-exchange resins are used in the purification of foods, 
including potable water, to remove undesirable ions or to replace less 
desirable ions with one or more of the following: bicarbonate, calcium, 
carbonate, chloride, hydrogen, hydroxyl, magnesium, potassium, sodium, 
and sulfate except that: The ion-exchange resin identified in paragraph 
(a)(12) of this section is used only in accordance with paragraph (b)(1) 
of this section, the ion-exchange resin identified in paragraph (a)(13) 
of this section is used only in accordance with paragraph (b)(2) of this 
section, the resin identified in paragraph (a)(16) of this section is 
used only in accordance with paragraph (b)(1) or (b)(2) of this section, 
the ion-exchange resin identified in paragraph (a)(17) of this section 
is used only in accordance with paragraph (b)(3) of this section, the 
ion-exchange resin identified in paragraph (a)(18) of this section is 
used only in accordance with paragraph (b)(4) of this section, and the 
ion-exchange resin identified in paragraph (a)(20) of this section is 
used only in accordance with paragraphs (b)(5) and (d) of this section.
    (1) The ion-exchange resins identified in paragraphs (a) (12) and 
(16) of this section are used to treat water for use in the manufacture 
of distilled alcoholic beverages, subject to the following conditions:
    (i) The water is subjected to treatment through a mixed bed 
consisting of one of the resins identified in paragraph (a) (12) or (16) 
of this section and one of the strongly acidic cation-exchange resins in 
the hydrogen form identified in paragraphs (a) (1), (2), and (11) of 
this section; or
    (ii) The water is first subjected to one of the resins identified in 
paragraph (a) (12) or (16) of this section and is subsequently subjected 
to treatment through a bed of activated carbon or one of the strongly 
acidic cation-exchange resins in the hydrogen form identified in 
paragraphs (a) (1), (2), and (11) of this section.
    (iii) The temperature of the water passing through the resin beds 
identified in paragraphs (b)(1) (i) and (ii) of this section is 
maintained at 30 [deg]C or less, and the flow rate of the water passing 
through the beds is not less than 2 gallons per cubic foot per minute.
    (iv) The ion-exchange resins identified in paragraph (a) (12) or 
(16) of this section are exempted from the requirements of paragraph 
(c)(4) of this section, but the strongly acidic cation-exchange resins 
referred to in paragraphs (b)(1) (i) and (ii) of this section used in 
the process meet the requirements of paragraph (c)(4) of this section, 
except for the exemption described in paragraph (d) of this section.
    (2) The ion-exchange resins identified in paragraphs (a) (13) and 
(16) of this section are used to treat water and aqueous food only of 
the types identified under Categories I, II, and VI-B in table 1 of 
Sec.  176.170(c) of this chapter: Provided, That the temperature of the 
water or food passing through the resin beds is maintained at 50 [deg]C 
or less and the flow rate of the water or food passing through the beds 
is not less than 0.5 gallon per cubic foot per minute.
    (i) The ion-exchange resin identified in paragraph (a)(13) of this 
section is used to treat water and aqueous food only of the types 
identified under categories I, II, and VI-B in Table 1 of Sec.  
176.170(c) of this chapter: Provided, That the temperature of the water 
or food passing through the resin bed is maintained at 50 [deg]C or less 
and the flow rate of the water or food passing

[[Page 124]]

through the bed is not less than 0.5 gallon per cubic foot per minute.
    (ii) The ion-exchange resin identified in paragraph (a)(16) of this 
section is used to treat water and aqueous food only of the types 
identified under categories I, II, and VI-B in Table 1 of Sec.  
176.170(c) of this chapter, Provided, that either:
    (A) The temperature of the water or food passing through the resin 
bed is maintained at 50 [deg]C or less and the flow rate of the water or 
food passing through the bed is not less than 0.5 gallon per cubic foot 
per minute; or
    (B) Extracts of the resin will be found to contain no more than 1 
milligram/kilogram dimethylaminopropylamine in each of the food 
simulants, distilled water and 10 percent ethanol, when, following 
washing and pretreatment of the resin in accordance with Sec.  
173.25(c)(1), the resin is subjected to the following test under 
conditions simulating the actual temperature and flow rate of use: ``The 
Determination of 3-Dimethylaminopropylamine in Food Simulating Extracts 
of Ion Exchange Resins,'' February 4, 1998, which is incorporated by 
reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies 
are available from the Division of Petition Control (HFS-215), Center 
for Food Safety and Applied Nutrition, Food and Drug Administration, 
5100 Paint Branch Pkwy., College Park, MD 20740, or may be examined at 
the Center for Food Safety and Applied Nutrition's Library, 5100 Paint 
Branch Pkwy., College Park, MD 20740, or at the National Archives and 
Records Administration (NARA). For information on the availability of 
this material at NARA, call 202-741-6030, or go to: http://
www.archives.gov/federal--register/code--of--federal--regulations/ibr--
locations.html.
    (3) The ion-exchange resin identified in paragraph (a)(17) of this 
section is used only for industrial application to treat bulk quantities 
of aqueous food, including potable water, or for treatment of municipal 
water supplies, subject to the condition that the temperature of the 
food or water passing through the resin bed is maintained at 25 [deg]C 
or less and the flow rate of the food or water passing through the bed 
is not less than 2 gallons per cubic foot per minute.
    (4) The ion-exchange resin identified in paragraph (a)(18) of this 
section is used to treat aqueous sugar solutions subject to the 
condition that the temperature of the sugar solution passing through the 
resin bed is maintained at 82 [deg]C (179.6 [deg]F) or less and the flow 
rate of the sugar solution passing through the bed is not less than 46.8 
liters per cubic meter (0.35 gallon per cubic foot) of resin bed volume 
per minute.
    (5) The ion-exchange resin identified in paragraph (a)(20) of this 
section is limited to use in aqueous process streams for the isolation 
and purification of protein concentrates and isolates under the 
following conditions:
    (i) For resins that comply with the requirements in paragraph 
(d)(2)(i) of this section, the pH range for the resin shall be no less 
than 3.5 and no more than 9, and the temperatures of water and food 
passing through the resin bed shall not exceed 25 [deg]C.
    (ii) For resins that comply with the requirements in paragraph 
(d)(2)(ii) of this section, the pH range for the resin shall be no less 
than 2 and no more than 10, and the temperatures of water and food 
passing through the resin shall not exceed 50 [deg]C.
    (c) To insure safe use of ion-exchange resins, each ion-exchange 
resin will be:
    (1) Subjected to pre-use treatment by the manufacturer and/or the 
user in accordance with the manufacturer's directions prescribed on the 
label or labeling accompanying the resins, to guarantee a food-grade 
purity of ion-exchange resins, in accordance with good manufacturing 
practice.
    (2) Accompanied by label or labeling to include directions for use 
consistent with the intended functional purpose of the resin.
    (3) Used in compliance with the label or labeling required by 
paragraph (c)(2) of this section.
    (4) Found to result in no more than 1 part per million of organic 
extractives obtained with each of the named solvents, distilled water, 
15 percent alcohol, and 5 percent acetic acid when, having been washed 
and otherwise treated in accordance with the manufacturer's directions 
for preparing

[[Page 125]]

them for use with food, the ion-exchange resin is subjected to the 
following test: Using a separate ion-exchange column for each solvent, 
prepare columns using 50 milliliters of the ready to use ion-exchange 
resin that is to be tested. While maintaining the highest temperature 
that will be encountered in use pass through these beds at the rate of 
350-450 milliliters per hour the three test solvents distilled water, 15 
percent (by volume) ethyl alcohol, and 5 percent (by weight) acetic 
acid. The first liter of effluent from each solvent is discarded, then 
the next 2 liters are used to determine organic extractives. The 2-liter 
sample is carefully evaporated to constant weight at 105 [deg]C; this is 
total extractives. This residue is fired in a muffle furnace at 850 
[deg]C to constant weight; this is ash. Total extractives, minus ash 
equals the organic extractives. If the organic extractives are greater 
than 1 part per million of the solvent used, a blank should be run on 
the solvent and a correction should be made by subtracting the total 
extractives obtained with the blank from the total extractives obtained 
in the resin test. The solvents used are to be made as follows:

Distilled water (de-ionized water is distilled).
15 percent ethyl alcohol made by mixing 15 volumes of absolute ethyl 
alcohol A.C.S. reagent grade, with 85 volumes of distilled de-ionized 
water.
5 percent acetic acid made by mixing 5 parts by weight of A.C.S. reagent 
grade glacial acetic acid with 95 parts by weight of distilled de-
ionized water.


In addition to the organic extractives limitation prescribed in this 
paragraph, the ion-exchange resin identified in paragraph (a)(17) of 
this section, when extracted with each of the named solvents, distilled 
water, 50 percent alcohol, and 5 percent acetic acid, will be found to 
result in not more than 7 parts per million of nitrogen extractives 
(calculated as nitrogen) when the resin in the free-base form is 
subjected to the following test immediately before each use: Using a 
separate 1-inch diameter glass ion-exchange column for each solvent, 
prepare each column using 100 milliliters of ready to use ion-exchange 
resin that is to be tested. With the bottom outlet closed, fill each 
ion-exchange column with one of the three solvents at a temperature of 
25 [deg]C until the solvent level is even with the top of the resin bed. 
Seal each column at the top and bottom and store in a vertical position 
at a temperature of 25 [deg]C. After 96 hours, open the top of each 
column, drain the solvent into a collection vessel, and analyze each 
drained solvent and a solvent blank for nitrogen by a standard micro-
Kjeldahl method.
    (d)(1) The ion-exchange resins identified in paragraphs (a)(1), 
(a)(2), (a)(11), and (a)(15) of this section are exempted from the 
acetic acid extraction requirement of paragraph (c)(4) of this section.
    (2) The ion-exchange resin identified in paragraph (a)(20) of this 
section shall comply either with:
    (i) The extraction requirement in paragraph (c)(4) of this section 
by using dilute sulfuric acid, pH 3.5 as a substitute for acetic acid; 
or
    (ii) The extraction requirement in paragraph (c)(4) of this section 
by using reagent grade hydrochloric acid, diluted to pH 2, as a 
substitute for acetic acid. The resin shall be found to result in no 
more than 25 parts per million of organic extractives obtained with each 
of the following solvents: Distilled water; 15 percent alcohol; and 
hydrochloric acid, pH 2. Blanks should be run for each of the solvents, 
and corrections should be made by subtracting the total extractives 
obtained with the blank from the total extractives obtained in the resin 
test.
    (e) Acrylonitrile copolymers identified in this section shall comply 
with the provisions of Sec.  180.22 of this chapter.

[42 FR 14526, Mar. 15, 1977, as amended at 46 FR 40181, Aug. 7, 1981; 46 
FR 57033, Nov. 20, 1981; 49 FR 28830, July 17, 1984; 56 FR 16268, Apr. 
22, 1991; 62 FR 7679, Feb. 20, 1997; 64 FR 14609, Mar. 26, 1999; 64 FR 
56173, Oct. 18, 1999]





Additives that reference this regulation:


Source: U.S. Code of Federal Regulations - CFR Title 21, Part 173, Section 25


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