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to control the temperature of the hotplate at the desired setting.

1. Dry ice trap with wide-mouth Dewar flask.

J. Safety shield for desiccator.

2. Aluminum tray, 51⁄2 x 8 x 1 inch deepCommercial frozen-food trays of this size are satisfactory.

3. Shield, drip or spatter-Unfold the corners of an aluminum tray, puncture hole for thermocouple lead, and place loosely over the sample dishes.

4. Drying dishes, aluminum, 50-millimeter diameter, with covers.

5. Oven, drying, maintained at 110° C. +2° C.

6. Glass wool, Pyrex.

Procedure. Assemble the apparatus as shown in the diagram.

Take sufficient glass wool to fill the weighing dish about three-fourths full when loosely packed. Roll the glass wool into a loose spiral and place in a clean, dry dish. Pass a flame from a Bunsen burner over the surface of the dish so as to melt off any stray wisps of the glass wool. Wipe off any glass fibers on the outside surface of the dish. Heat the uncovered dishes in a 110° C. oven for 30 minutes, remove, cover, cool in air, and weigh to the nearest 0.0001 gram. Pipet about 10-milliliter aliquots of the sample solution into the dish, wetting the entire glass wool pad.

Place the uncovered dishes in an aluminum tray, maximum of eight dishes per tray. With the hotplate at room temperature and the power off, place the tray of dishes on its top surface. Place the drip or spatter shield loosely over the tray. Place the desiccator lid and guard in position. Make sure the thermocouple is pressing against the bottom of the tray. Fill the cooling bath with ice plus a small amount of water.

Add crushed dry ice to the cooling trap Dewar flask and turn the vacuum pump on. Apply heat at such a rate that the temperature reaches 130° C.-140° C. in 40 to 60 minutes, usually about 80-volt setting of the Variac. Control the temperature at 140° C. for another hour. The pressure should be 800 microns to 1,000 microns at the start, and near the end of the test should drop to 300 microns to 500 microns.

Finally close off the lead to the vacuum pump, turn off the hotplate, and fill the desiccator slowly with nitrogen (about 5 pounds per square inch) admitted through a capillary. Attach the nitrogen feedline from the capillary to the horizontal arm of the glass tee. While holding a soft-rubber stopper on the flat surface of the vertical arm, slowly open the stopcock to the desiccator. Release the stopper; the vacuum will hold it in place until atmospheric pressure is reached, when it will pop off. This prevents blowing the lid off by pressure buildup. Open the desiccator, remove the shield, and then lift out the tray with the drying dishes.

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Milliliters of solution taken for total solids determination,

20 Total volume of solvent used in dissolving the sample.

Specify the solvent used along with the percent soluble result.

(ii) Method II-Ethyl acetate or hexane extractive.

A sample is refluxed in the solvent for 2 hours and filtered at the boiling point. The filtrate is évaporated and the total residue weighed as a measure of the solvent extractable fraction.

Apparatus. 1. Erlenmeyer flasks, 250milliliter, with ground joint.

2. Condensers, Allihn, 400-millimeter jacket, with ground joint.

3. Funnels, ribbed, 75-millimeter diameter, stem cut to 40 millimeters.

4. Funnels, Buchner type, with fritted disc, 60-milliliter, porosity coarse.

5. Bell jar for vacuum filtration into beaker.

Reagents. 1. Ethyl acetate, 99 percent 20° C. specific gravity0.899-0.902. 20° C. 2. n-Hexane, commercial grade, specific 20° C. 0.663-0.667; boiling range 66° gravity 20° C. C.-69° C., or equivalent.

Procedure. Weigh 1 gram of sample accurately and place in a 250-milliliter Erlenmeyer flask containing two or three boiling stones. Add 100 milliliters of solvent, attach the flask to the condenser (use no grease) and reflux the mixture for two hours.1

Remove the flask from the heat, disconnect the condenser, and filter rapidly while still hot through a small wad of glass wool packed in a short stem funnel into a tared 150milliliter beaker. Rinse the flask and filter with two 10-milliliter portions of the hot solvent, and add the rinsings to the filtrate. Evaporate the filtrate on a steam bath with the aid of a stream of nitrogen. Dry the residue in a vacuum oven at 110° C. for two hours, cool in a desiccator and weigh to 0.0001 gram.

1n-Hexane is refluxed on a steam bath.

A glass-sintered funnel under slight vacuum is used for flake or ground material. Preheat the funnel with about 25 milliliters of hot solvent.

Determine the blank on 100 milliliters of solvent evaporated in a tared 150-milliliter beaker. Correct the sample residue for this

blank if significant.

Calculation:

Grams of residue

Grams of sample

X 100

= percent extractable with Specify the solvent used along with the percent extractive result.

§ 121.2502 Nylon resins.

The nylon resins listed in paragraph (a) of this section may be safely used to produce articles intended for use in processing, handling, and packaging food, subject to the provisions of this section:

(a) The nylon resins are manufactured as described in this paragraph so as to meet the specifications prescribed in paragraph (b) of this section when tested by the methods described in paragraph (c) of this section.

(1) Nylon 66 resins are manufactured

by the condensation of hexamethylenediamine and adipic acid.

(2) Nylon 610 resins are manufactured by the condensation of hexamethylenediamine and sebacic acid.

(3) Nylon 66/610 resins are manufactured by the condensation of equalweight mixtures of nylon 66 salts and nylon 610 salts.

(4) Nylon 6/66 resins are manufactured by the condensation and polymerization of mixtures of nylon 66 salts and epsilon-caprolactam under such conditions that the epsilon-caprolactam monomer content does not exceed 0.7 percent by weight of the finished nylon 6/66 resins.

(5) Nylon 11 resins are manufactured by the condensation of 11-aminoundecanoic acid.

(6) Nylon 6 resins are manufactured by the polymerization of epsilon-caprolactam.

(b) Specifications.

Maximum extractable fraction in selected solvents (expressed as percent by weight of resin)

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3 Nylon 66/610 resins.

4 Nylon 6/66 resins. 5.1 Nylon 11 resins for use in articles intended for one-time use or repeated use in contact with food. 5.2 Nylon 11 resins for use only:

a. In articles intended for repeated use in contact with food.

b. In side-seam

cements for articles intended for onetime use in contact with food and which are in compliance with § 121.2514.

6.1 Nylon 6 resins....

6.2 Nylon 6 resins for use only in food-contact films having an average thickness not to exceed 0.001 inch.

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(c) Analytical methods. (1) Specific gravity. Specific gravity shall be determined by weighing a 1-gram to 5-gram sample first in air and then in freshly boiled distilled water at 23° C. ±2° C.

(2) Melting point. The melting point shall be determined as follows: Use a

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hot-stage apparatus. The use of crossed nicol prisms with a microscope hot stage and reading of the thermometer when the birefringence disappears increases the accuracy. If the crossed nicol apparatus is not available, use the lowest temperature at which the sample be

comes transparent or the sharp edges or corners of the sample become rounded as the melting point. In case of doubt as to the onset of melting, the sample is prodded with a sharp instrument. If it sticks to the heating block, it is considered to have melted. If the melting point is low, dry the sample in an oven at 85° C. for 24 hours in a nitrogen atmosphere, then repeat the test.

(3) Solubility in boiling 4.2N HCl. The test shall be run on a sample approximately the size of a 1⁄4-inch cube in at least 25 milliliters of 4.2 normal hydrochloric acid.

(4) Maximum extractable fraction in selected solvents. The procedure for determining the maximum extractable fraction of the nylon resins in selected solvents is as follows:

(i) Film should be cut with ordinary scissors into pieces of a convenient size such as 1/4-inch squares, for the extraction tests described in this section.

The

granules of nylon molding powders are in the proper form for the extraction tests. Samples of fabricated articles such as pipe, fittings, and other similar articles must be cut to approximately the size of the molding powder. This can be done conveniently by using a smallscale commercial plastics granulator and cutting the sample through a screen having 1/4-inch mesh. Fine particles should be separated from the cut resin by screening through a 20-mesh screen. The material retained on the screen is suitable for the extraction tests.

(ii) The organic solvents must be of American Chemical Society analytical reagent grade; distilled water is used. Approximately 30 grams of the prepared sample is weighed to the nearest milligram. The weighed resin is transferred to a 500-milliliter round-bottom flask equipped with a reflux condenser. Approximately 300-milliliters of solvent is added to the flask and the contents refluxed gently for 8 hours with a heating mantle. The solvent is then filtered off immediately while still hot, using a Buchner funnel approximately 5 inches in diameter, a suction flask, and a hardened filter paper (Whatman No. 50 or equivalent). The paper is wet with the solvent and a slight suction applied just before starting the filtration. The resin is washed twice with approximately 100milliliter portions of solvent and the combined filtrate and washings are reduced to approximately 25 milliliters by evaporation at reduced pressure (50 mil

limeters to 100 millimeters of mercury, absolute), heating as necessary. The contents of the flask are transferred to an evaporation dish (which has been held in a vacuum desiccator over anhydrous calcium sulfate until constant weight has been attained) and carefully evaporated to dryness. The weight of the solid residue is determined by difference after holding in a vacuum desiccator over anhydrous calcium sulfate until constant weight has been attained. The percent of solids extracted is calculated by dividing the weight of the solid residue by the weight of the sample and multiplying by 100.

§ 121.2503 Polyterpene resins.

Polyterpene resins identified in this section may be safely used as components of polypropylene film intended for use in contact with food, in accordance with the following prescribed conditions:

(a) The polyterpene resins are the hydrogenated polymers of terpene hydrocarbons obtainable from sulfate turpentine.

(b) The polyterpene resins have a drop-softening point of 118° C.-138° C. and an iodine value of less than 20. § 121.2504 Malathion.

Malathion may be safely used for the control of insects during the drying of grapes (raisins) in compliance with § 121.1172 by incorporation into paper trays in amounts not exceeding 200 milligrams per square foot.

§ 121.2505 Slimicides.

(a) Slimicides may be safely used in the manufacture of paper and paperboard that contact food, in accordance with the following prescribed conditions:

(1) Slimicides are used as antimicrobial agents to control slime in the manufacture of paper and paperboard.

(2) Subject to any prescribed limitations, slimicides are prepared from one or more of the slime-control substances named in paragraph (c) of this section, to which may be added optional adjuvant substances as provided for under paragraph (d) of this section.

(3) Slimicides are added to the process water used in the production of paper or paperboard, and the quantity added shall not exceed the amount necessary to accomplish the intended technical effect.

(b) To insure safe usage, the label or labeling of slimicides shall bear adequate directions for use.

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and pr.perboard, substances permitted to be used in paper and paperboard by other regulations in this chapter, and the following:

Acetone.

Butylene oxide.

N,N-Dimethylformamide.

Ethanolamine.

Ethylenediamine.

Monomethyl ethers of mono-, di-, and tripropylene glycol.

§ 121.2506 Industrial starch-modified.

Industrial starch-modified may be safely used as a component of articles intended for use in producing, manufacturing, packing, processing, preparing, treating, packaging, transporting, or holding food, subject to the provisions of this section.

(a) Industrial starch-modified is a food starch-modified or starch or any combination thereof that has been modified by treatment with one of the reactants hereinafter specified, in an amount reasonably required to achieve the desired functional effect but in no event in excess of any limitation prescribed, with or without subsequent treatment as authorized in § 121.1031.

(b) The following adjuvants may be used as surface-active agents in the processing of industrial starch-modified: Polyethylene glycol (400) dilaurate. Polyethylene glycol (400) monolaurate. Polyoxyethylene (4) lauryl ether. Polyoxyethylene (20) sorbitan trioleate. Sorbitan monolaurate.

(c) To insure safe use of the industrial starch-modified, the label of the food additive container shall bear the name of the additive "industrial starch-modified," and in the instance of an industrial starch-modified which is limited with respect to conditions of use, the label of the food additive container shall contain a statement of such limited use.

Chlorine, 0.055 pound, as sodium hypochlorite, per pound of dry starch and epichlorohydrin, not to exceed 0.3 percent.

Limitations

(4-Chlorobutene-2) trimethylammonium chloride, Industrial starch modified by this

not to exceed 5 percent.

B-Diethylaminoethyl chloride hydrochloride, not to exceed 4 percent.

Dimethylaminoethyl methacrylate, not to exceed

3 percent.

treatment shall be used only as internal sizing for paper and paperboard intended for food packaging.

Dimethylol ethylene urea, not to exceed 0.375 per- Industrial starch modified by this cent.

treatment shall be used only as internal sizing for paper and paperboard intended for food packaging.

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