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178.3620 Mineral oil.

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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: 21CFR178.3620]

[Page 416-425]
 
                        TITLE 21--FOOD AND DRUGS
 
CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN 
                          SERVICES (CONTINUED)
 
PART 178_INDIRECT FOOD ADDITIVES: ADJUVANTS, PRODUCTION AIDS, AND 
SANITIZERS--Table of Contents
 
             Subpart D_Certain Adjuvants and Production Aids
 
Sec.  178.3620  Mineral oil.

    Mineral oil may be safely used as a component of nonfood articles 
intended for use in contact with food, subject to the provisions of this 
section:
    (a) White mineral oil meeting the specifications prescribed in Sec.  
172.878 of this chapter may be used as a component of nonfood articles 
provided such use complies with any applicable limitations in parts 170 
through 189 of this chapter. The use of white mineral oil in or on food 
itself, including the use of white mineral oil as a protective coating 
or release agent for food, is subject to the provisions of Sec.  172.878 
of this chapter.
    (b) Technical white mineral oil identified in paragraph (b)(1) of 
this section may be used as provided in paragraph (b)(2) of this 
section.
    (1) Technical white mineral oil consists of specially refined 
distillates of virgin petroleum or of specially refined distillates that 
are produced synthetically from petroleum gases. Technical white mineral 
oil meets the following specifications:
    (i) Saybolt color 20 minimum as determined by ASTM method D156-82, 
``Standard Test Method for Saybolt Color of Petroleum Products (Saybolt 
Chromometer Method),'' which is incorporated by reference. Copies may be 
obtained from the American Society for Testing Materials, 100 Barr 
Harbor Dr., West Conshohocken, Philadelphia, PA 19428-2959, or may be 
examined 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.
    (ii) Ultraviolet absorbance limits as follows:

------------------------------------------------------------------------
                                                                Maximum
                                                                absorb
                                                               ance per
                    Wavelength (m[micro])                     centimeter
                                                                optical
                                                              pathlength
------------------------------------------------------------------------
280 to 289..................................................         4.0
290 to 299..................................................         3.3
300 to 329..................................................         2.3
330 to 350..................................................         0.8
------------------------------------------------------------------------


Technical white mineral oil containing antioxidants shall meet the 
specified ultraviolet absorbance limits after correction for any 
absorbance due to the

[[Page 417]]

antioxidants. The ultraviolet absorbance shall be determined by the 
procedure described for application to mineral oil under 
``Specification'' on page 66 of the ``Journal of the Association of 
Official Agricultural Chemists,'' Volume 45 (February 1962) (which is 
incorporated by reference; copies are available from the Center for Food 
Safety and Applied Nutrition (HFS-200), Food and Drug Administration, 
5100 Paint Branch Pkwy., College Park, MD 20740, 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.), disregarding the last two 
sentences of that procedure and substituting therefor the following: 
Determine the absorbance of the mineral oil extract in a 10-millimeter 
cell in the range from 260-350 m[micro], inclusive, compared to the 
solvent control. If the absorbance so measured exceeds 2.0 at any point 
in range 280-350 m[micro], inclusive, dilute the extract and the solvent 
control, respectively, to twice their volume with dimethyl sulfoxide and 
remeasure the absorbance. Multiply the remeasured absorbance values by 2 
to determine the absorbance of the mineral oil extract per centimeter 
optical pathlength.
    (2) Technical white mineral oil may be used wherever mineral oil is 
permitted for use as a component of nonfood articles complying with 
Sec. Sec.  175.105, 176.200, 176.210, 177.2260, 177.2600, and 177.2800 
of this chapter and Sec. Sec.  178.3570 and 178.3910.
    (3) Technical white mineral oil may contain any antioxidant 
permitted in food by regulations issued in accordance with section 409 
of the Act, in an amount not greater than that required to produce its 
intended effect.
    (c) Mineral oil identified in paragraph (c)(1) of this section may 
be used as provided in paragraph (c)(2) of this section.
    (1) The mineral oil consists of virgin petroleum distillates refined 
to meet the following specifications:
    (i) Initial boiling point of 450 [deg]F minimum.
    (ii) Color 5.5 maximum as determined by ASTM method D1500-82, 
``Standard Test Method for ASTM Color of Petroleum Products (ASTM Color 
Scale),'' which is incorporated by reference. The availability of this 
incorporation by reference is given in paragraph (b)(1)(i) of this 
section.
    (iii) Ultraviolet absorbance limits as follows as determined by the 
analytical method described in paragraph (c)(3) of this section:

------------------------------------------------------------------------
                                                                Maximum
                                                                absorb
                                                               ance per
                    Wavelength (m[micro])                     centimeter
                                                                optical
                                                              pathlength
------------------------------------------------------------------------
280 to 289..................................................         0.7
290 to 299..................................................         0.6
300 to 359..................................................         0.4
360 to 400..................................................         .09
------------------------------------------------------------------------

    (2) The mineral oil may be used wherever mineral oil is permitted 
for use as a component of nonfood articles complying with Sec. Sec.  
175.105 and 176.210 of this chapter and Sec.  178.3910 (for use only in 
rolling of metallic foil and sheet stock), Sec. Sec.  176.200, 177.2260, 
177.2600, and 177.2800 of this chapter.
    (3) The analytical method for determining ultraviolet absorbance 
limit is as follows:

                          general instructions

    Because of the sensitivity of the test, the possibility of errors 
arising from contamination is great. It is of the greatest importance 
that all glassware be scrupulously cleaned to remove all organic matter 
such as oil, grease, detergent residues, etc. Examine all glassware, 
including stoppers and stopcocks, under ultraviolet light to detect any 
residual fluorescent contamination. As a precautionary measure it is 
recommended practice to rinse all glassware with purified isooctane 
immediately before use. No grease is to be used on stopcocks or joints. 
Great care to avoid contamination of oil samples in handling and to 
assure absence of any extraneous material arising from inadequate 
packaging is essential. Because some of the polynuclear hydrocarbons 
sought in this test are very susceptible to photo-oxidation, the entire 
procedure is to be carried out under subdued light.

                                apparatus

    Separatory funnels. 250-milliliter, 500-milliliter, 1,000-
milliliter, and preferably 2,000-milliliter capacity, equipped with 
tetrafluoroethylene polymer stopcocks.

[[Page 418]]

    Reservoir. 500-milliliter capacity, equipped with a 24/40 standard 
taper male fitting at the bottom and a suitable ball-joint at the top 
for connecting to the nitrogen supply. The male fitting should be 
equipped with glass hooks.
    Chromatographic tube. 180 millimeters in length, inside diameter to 
be 15.7 millimeters 0.1 millimeter, equipped with 
a coarse, fritted-glass disc, a tetrafluoroethylene polymer stopcock, 
and a female 24/40 standard tapered fitting at the opposite end. 
(Overall length of the column with the female joint is 235 millimeters.) 
The female fitting should be equipped with glass hooks.
    Disc. Tetrafluoroethylene polymer 2-inch diameter disk approximately 
\3/16\-inch thick with a hole bored in the center to closely fit the 
stem of the chromatographic tube.
    Suction flask. 250-milliliter or 500-milliliter filter flask.
    Condenser. 24/40 joints, fitted with a drying tube, length optional.
    Evaporation flask (optional). 250-milliliter or 500-milliliter 
capacity all-glass flask equipped with standard taper stopper having 
inlet and outlet tubes to permit passage of nitrogen across the surface 
of contained liquid to be evaporated.
    Spectrophotometric cells. Fused quartz cells, optical path length in 
the range of 5,000 centimeter 0.005 centimeter; 
also for checking spectrophotometer performance only, optical path 
length in the range 1,000 centimeter 0.005 
centimeter. With distilled water in the cells, determine any absorbance 
differences.
    Spectrophotometer. Spectral range 250 millimicrons--400 millimicrons 
with spectral slit width of 2 millimicrons or less; under instrument 
operating conditions for these absorbance measurements, the 
spectrophotometer shall also meet the following performance 
requirements:
    Absorbance repeatability, 0.01 at 0.4 
absorbance.
    Absorbance accuracy \1\ 0.05 at 0.4 
absorbance.
---------------------------------------------------------------------------

    \1\ As determined by procedure using potassium chromate for 
reference standard and described in National Bureau of Standards 
Circular 484, Spectrophotometry, U.S. Department of Commerce (1949). The 
accuracy is to be determined by comparison with the standard values at 
290, 345, and 400 millimicrons. Circular 484 is incorporated by 
reference. Copies are available from the Center for Food Safety and 
Applied Nutrition (HFS-200), Food and Drug Administration, 5100 Paint 
Branch Pkwy., College Park, MD 20740, 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.
---------------------------------------------------------------------------

    Wavelength accuracy, 1.0 millimicron.
    Nitrogen cylinder. Water-pumped or equivalent purity nitrogen in 
cylinder equipped with regulator and valve to control flow at 5 p.s.i.g.

                         reagents and materials

    Organic solvents. All solvents used throughout the procedure shall 
meet the specifications and tests described in this specification. The 
isooctane, benzene, acetone, and methyl alcohol designated in the list 
following this paragraph shall pass the following test:
    To the specified quantity of solvent in a 250-milliliter Erlenmeyer 
flask, add 1 milliliter of purified n-hexadecane and evaporate on the 
steam bath under a stream of nitrogen (a loose aluminum foil jacket 
around the flask will speed evaporation). Discontinue evaporation when 
not over 1 milliliter of residue remains. (To the residue from benzene 
add a 10-milliliter portion of purified isooctane, reevaporate, and 
repeat once to insure complete removal of benzene.)
    Alternatively, the evaporation time can be reduced by using the 
optional evaporation flask. In this case the solvent and n-hexadecane 
are placed in the flask on the steam bath, the tube assembly is 
inserted, and a stream of nitrogen is fed through the inlet tube while 
the outlet tube is connected to a solvent trap and vacuum line in such a 
way as to prevent any flow-back of condensate into the flask.
    Dissolve the 1 milliliter of hexadecane residue in isooctane and 
make to 25 milliliters volume. Determine the absorbance in the 5-
centimeter path length cells compared to isooctane as reference. The 
absorbance of the solution of the solvent residue (except for methyl 
alcohol) shall not exceed 0.01 per centimeter path length between 280 
and 400 m[micro]. For methyl alcohol this absorbance value shall be 
0.00.
    Isooctane (2,2,4-trimethylpentane). Use 180 milliliters for the test 
described in the preceding paragraph. Purify, if necessary, by passage 
through a column of activated silica gel (Grade 12, Davison Chemical 
Company, Baltimore, Maryland, or equivalent) about 90 centimeters in 
length and 5 centimeters to 8 centimeters in diameter.
    Benzene, A.C.S. reagent grade. Use 150 milliliters for the test. 
Purify, if necessary, by distillation or otherwise.
    Acetone, A.C.S. reagent grade. Use 200 milliliters for the test. 
Purify, if necessary, by distillation.
    Eluting mixtures:
    1. 10 percent benzene in isooctane. Pipet 50 milliliters of benzene 
into a 250-milliliter

[[Page 419]]

glass-stoppered volumetric flask and adjust to volume with isooctane, 
with mixing.
    2. 20 percent benzene in isooctane. Pipet 50 milliliters of benzene 
into a 250-milliliter glass-stoppered volumetric flask and adjust to 
volume with isooctane, with mixing.
    3. Acetone-benzene-water mixture. Add 20 milliliters of water to 380 
milliliters of acetone and 200 milliliters of benzene, and mix.
    n-Hexadecane, 99-percent olefin-free. Dilute 1.0 milliliter of n-
hexadecane to 25 milliliters with isooctane and determine the absorbance 
in a 5-centimeter cell compared to isooctane as reference point between 
280 m[micro]-400 m[micro]. The absorbance per centimeter path length 
shall not exceed 0.00 in this range. Purify, if necessary, by 
percolation through activated silica gel or by distillation.
    Methyl alcohol, A.C.S. reagent grade. Use 10.0 milliliters of methyl 
alcohol. Purify, if necessary, by distillation.
    Dimethyl sulfoxide. Spectrophotometric grade (Crown Zellerbach 
Corporation, Camas, Washington, or equivalent). Absorbance (1-centimeter 
cell, distilled water reference, sample completely saturated with 
nitrogen).

------------------------------------------------------------------------
                                                                Absorb
                         Wavelength                              ance
                                                               (maximum)
------------------------------------------------------------------------
261.5.......................................................        1.00
270.........................................................         .20
275.........................................................         .09
280.........................................................         .06
300.........................................................        .015
------------------------------------------------------------------------

There shall be no irregularities in the absorbance curve within these 
wavelengths.
    Phosphoric acid. 85 percent A.C.S. reagent grade.
    Sodium borohydride. 98 percent.
    Magnesium oxide (Sea Sorb 43, Food Machinery Company, Westvaco 
Division, distributed by chemical supply firms, or equivalent). Place 
100 grams of the magnesium oxide in a large beaker, add 700 milliliters 
of distilled water to make a thin slurry, and heat on a steam bath for 
30 minutes with intermittent stirring. Stir well initially to insure 
that all the adsorbent is completely wetted. Using a Buchner funnel and 
a filter paper (Schleicher & Schuell No. 597, or equivalent) of suitable 
diameter, filter with suction. Continue suction until water no longer 
drips from the funnel. Transfer the adsorbent to a glass trough lined 
with aluminum foil (free from rolling oil). Break up the magnesia with a 
clean spatula and spread out the adsorbent on the aluminum foil in a 
layer about 1 centimeter to 2 centimeters thick. Dry for 24 hours at 160 
[deg]C 1 [deg]C. Pulverize the magnesia with 
mortar and pestle. Sieve the pulverized adsorbent between 60-180 mesh. 
Use the magnesia retained on the 180-mesh sieve.
    Celite 545. Johns Mansville Company, diatomaceous earth, or 
equivalent.
    Magnesium oxide-Celite 545 mixture (2+1) by weight. Place the 
magnesium oxide (60-180 mesh) and the Celite 545 in 2 to 1 proportions, 
respectively, by weight in a glass-stoppered flask large enough for 
adequate mixing. Shake vigorously for 10 minutes. Transfer the mixture 
to a glass trough lined with aluminum foil (free from rolling oil) and 
spread it out on a layer about 1 centimeter to 2 centimeters thick. 
Reheat the mixture at 160 [deg]C 1 [deg]C for 2 
hours, and store in a tightly closed flask.
    Sodium sulfate, anhydrous, A.C.S. reagent grade, preferably in 
granular form. For each bottle of sodium sulfate reagent used, establish 
as follows the necessary sodium sulfate prewash to provide such filters 
required in the method: Place approximately 35 grams of anhydrous sodium 
sulfate in a 30-milliliter course, fritted-glass funnel or in a 65-
millimeter filter funnel with glass wool plug; wash with successive 15-
milliliter portions of the indicated solvent until a 15-milliliter 
portion of the wash shows 0.00 absorbance per centimeter path length 
between 280 m[micro] and 400 m[micro] when tested as prescribed under 
``Organic solvents.'' Usually three portions of wash solvent are 
sufficient.
    Before proceeding with analysis of a sample, determine the 
absorbance in a 5-centimeter path cell between 250 millimicrons and 400 
millimicrons for the reagent blank by carrying out the procedure, 
without an oil sample, recording the spectra after the extraction stage 
and after the complete procedure as prescribed. The absorbance per 
centimeter pathlength following the extraction stage should not exceed 
0.02 in the wavelength range from 280 m[micro] to 400 m[micro]; the 
absorbance per centimeter pathlength following the complete procedure 
should not exceed 0.02 in the wavelength range from 280 m[micro] to 400 
m[micro]. If in either spectrum the characteristic benzene peaks in the 
250 m[micro]-260 m[micro] region are present, remove the benzene by the 
procedure under ``Organic solvents'' and record absorbance again.
    Place 300 milliliters of dimethyl sulfoxide in a 1-liter separatory 
funnel and add 75 milliliters of phosphoric acid. Mix the contents of 
the funnel and allow to stand for 10 minutes. (The reaction between the 
sulfoxide and the acid is exothermic. Release pressure after mixing, 
then keep funnel stoppered.) Add 150 milliliters of isooctane and shake 
to pre-equilibrate the solvents. Draw off the individual layers and 
store in glass-stoppered flasks.
    Weigh a 20-gram sample of the oil and transfer to a 500-milliliter 
separatory funnel containing 100 milliliters of pre-equilibrated 
sulfoxide-phosphoric acid mixture. Complete the transfer of the sample 
with small portions of preequilibrated isooctane to give a total volume 
of the oil and solvent of 75 milliliters. Shake the funnel vigorously 
for 2

[[Page 420]]

minutes. Set up three 250-milliliter separatory funnels with each 
containing 30 milliliters of pre-equilibrated isooctane. After 
separation of liquid phases, carefully draw off lower layer into the 
first 250-milliliter separatory funnel and wash in tandem with the 30-
milliliter portions of isooctane contained in the 250-milliliter 
separatory funnels. Shaking time for each wash is 1 minute. Repeat the 
extraction operation with two additional portions of the sulfoxide-acid 
mixture and wash each extractive in tandem through the same three 
portions of isooctane.
    Collect the successive extractives (300 milliliters total) in a 
separatory funnel (preferably 2-liter) containing 480 milliliters of 
distilled water; mix, and allow to cool for a few minutes after the last 
extractive has been added. Add 80 milliliters of isooctane to the 
solution and extract by shaking the funnel vigorously for 2 minutes. 
Draw off the lower aqueous layer into a second separatory funnel 
(preferably 2-liter) and repeat the extraction with 80 milliliters of 
isooctane. Draw off and discard the aqueous layer. Wash each of the 80-
milliliter extractives three times with 100-milliliter portions of 
distilled water. Shaking time for each wash is 1 minute. Discard the 
aqueous layers. Filter the first extractive through anhydrous sodium 
sulfate prewashed with isooctane (see Sodium sulfate under ``Reagents 
and Materials'' for preparation of filter) into a 250-milliliter 
Erlenmeyer flask (or optionally into the evaporation flask). Wash the 
first separatory funnel with the second 80-milliliter isooctane 
extractive and pass through the sodium sulfate. Then wash the second and 
first separatory funnels successively with a 20-milliliter portion of 
isooctane and pass the solvent through the sodium sulfate into the 
flask. Add 1 milliliter of n-hexadecane and evaporate the isooctane on 
the steam bath under nitrogen. Discontinue evaporation when not over 1 
milliliter of residue remains. To the residue, add a 10-milliliter 
portion of isooctane, reevaporate to 1 milliliter of hexadecane, and 
repeat this operation once.
    Quantitatively transfer the residue with isooctane to a 200-
milliliter volumetric flask, make to volume, and mix. Determine the 
absorbance of the solution in the 1-centimeter pathlength cells compared 
to isooctane as reference between 280 m[micro]-400 m[micro] (take care 
to lose none of the solution in filling the sample cell). Correct the 
absorbance values for any absorbance derived from reagents as determined 
by carrying out the procedure without an oil sample. If the corrected 
absorbance does not exceed the limits prescribed in this paragraph, the 
oil meets the ultraviolet absorbance specifications. If the corrected 
absorbance per centimeter pathlength exceeds the limits prescribed in 
this paragraph, proceed as follows: Quantitatively transfer the 
isooctane solution to a 125-milliliter flask equipped with 24/40 joint, 
and evaporate the isooctane on the steam bath under a stream of nitrogen 
to a volume of 1 milliliter of hexadecane. Add 10 milliliters of methyl 
alcohol and approximately 0.3 gram of sodium borohydride. (Minimize 
exposure of the borohydride to the atmosphere. A measuring dipper may be 
used.) Immediately fit a water-cooled condenser equipped with a 24/40 
joint and with a drying tube into the flask, mix until the borohydride 
is dissolved, and allow to stand for 30 minutes at room temperature, 
with intermittent swirling. At the end of this period, disconnect the 
flask and evaporate the methyl alcohol on the steam bath under nitrogen 
until the sodium borohydride begins to come out of the solution. Then 
add 10 milliliters of isooctane and evaporate to a volume of about 2-3 
milliliters. Again, add 10 milliliters of isooctane and concentrate to a 
volume of approximately 5 milliliters. Swirl the flask repeatedly to 
assure adequate washing of the sodium borohydride residues.
    Fit the tetrafluoroethylene polymer disc on the upper part of the 
stem of the chromatographic tube, then place the tube with the disc on 
the suction flask and apply the vacuum (approximately 135 millimeters Hg 
pressure). Weigh out 14 grams of the 2:1 magnesium oxide-Celite 545 
mixture and pour the adsorbent mixture into the chromatographic tube in 
approximately 3-centimeter layers. After the addition of each layer, 
level off the top of the adsorbent with a flat glass rod or metal 
plunger by pressing down firmly until the adsorbent is well packed. 
Loosen the topmost few millimeters of each adsorbent layer with the end 
of a metal rod before the addition of the next layer. Continue packing 
in this manner until all the 14 grams of the adsorbent is added to the 
tube. Level off the top of the adsorbent by pressing down firmly with a 
flat glass rod or metal plunger to make the depth of the adsorbent bed 
approximately 12.5 centimeters in depth. Turn off the vacuum and remove 
the suction flask. Fit the 500-milliliter reservoir onto the top of the 
chromatographic column and prewet the column by passing 100 milliliters 
of isooctane through the column. Adjust the nitrogen pressure so that 
the rate of descent of the isooctane coming off the column is between 2-
3 milliliters per minute. Discontinue pressure just before the last of 
the isooctane reaches the level of the adsorbent. (Caution: Do not allow 
the liquid level to recede below the adsorbent level at any time.) 
Remove the reservoir and decant the 5-milliliter isooctane concentrate 
solution onto the column and with slight pressure again allow the liquid 
level to recede to barely above the adsorbent level. Rapidly complete 
the transfer similarly with two 5-milliliter portions of isooctane, 
swirling the flask repeatedly each

[[Page 421]]

time to assure adequate washing of the residue. Just before the final 5-
milliliter wash reaches the top of the adsorbent, add 100 milliliters of 
isooctane to the reservoir and continue the percolation at the 2-3 
milliliters per minute rate. Just before the last of the isooctane 
reaches the adsorbent level, add 100 milliliters of 10 percent benzene 
in isooctane to the reservoir and continue the percolation at the 
aforementioned rate. Just before the solvent mixture reaches adsorbent 
level, add 25 milliliters of 20 percent benzene in isooctane to the 
reservoir and continue the percolation at 2-3 milliliters per minute 
until all this solvent mixture has been removed from the column. Discard 
all the elution solvents collected up to this point. Add 300 milliliters 
of the acetone-benzene-water mixture to the reservoir and percolate 
through the column to eluate the polynuclear compounds. Collect the 
eluate in a clean 1-liter separatory funnel. Allow the column to drain 
until most of the solvent mixture is removed. Wash the eluate three 
times with 300-milliliter portions of distilled water, shaking well for 
each wash. (The addition of small amounts of sodium chloride facilitates 
separation.) Discard the aqueous layer after each wash. After the final 
separation, filter the residual benzene through anhydrous sodium sulfate 
pre-washed with benzene (see Sodium sulfate under ``Reagents and 
Materials'' for preparation of filter) into a 250-milliliter Erlenmeyer 
flask (or optionally into the evaporation flask). Wash the separatory 
funnel with two additional 20-milliliter portions of benzene which are 
also filtered through the sodium sulfate. Add 1 milliliter of n-
hexadecane and completely remove the benzene by evaporation under 
nitrogen, using the special procedure to eliminate benzene as previously 
described under ``Organic solvents.'' Quantitatively transfer the 
residue with isooctane to a 200-milliliter volumetric flask and adjust 
to volume. Determine the absorbance of the solution in the 1-centimeter 
pathlength cells compared to isooctane as reference between 250 
m[micro]-400 m[micro]. Correct for any absorbance derived from the 
reagents as determined by carrying out the procedure without an oil 
sample. If either spectrum shows the characteristic benzene peaks in the 
250 m[micro]-260 m[micro] region, evaporate the solution to remove 
benzene by the procedure under ``Organic solvents.'' Dissolve the 
residue, transfer quantitatively, and adjust to volume in isooctane in a 
200-milliliter volumetric flask. Record the absorbance again. If the 
corrected absorbance does not exceed the limits proposed in this 
paragraph, the oil meets the proposed ultraviolet absorbance 
specifications.

    (d) Mineral oil identified in paragraph (d)(1) of this section may 
be used as provided in paragraph (d)(2) of this section.
    (1) The mineral oil consists of virgin petroleum distillates refined 
to meet the following specifications:
    (i) Distillation endpoint at 760 millimeters pressure not to exceed 
371 [deg]C, with a maximum residue not to exceed 2 percent, as 
determined by ASTM method D86-82, ``Standard Method for Distillation of 
Petroleum Products,'' which is incorporated by reference. The 
availability of this incorporation by reference is given in paragraph 
(b)(1)(i) of this section.
    (ii) Ultraviolet absorbance limits as follows as determined by the 
method described in paragraph (d)(3) of this section.

------------------------------------------------------------------------
                                                                Maximum
                                                                absorb-
                                                               ance per
                    Wavelength (m[micro])                     centimeter
                                                                optical
                                                              pathlength
------------------------------------------------------------------------
280 to 299..................................................         2.3
300 to 319..................................................         1.2
320 to 359..................................................          .8
360 to 400..................................................          .3
------------------------------------------------------------------------

    (iii) Pyrene content not to exceed a maximum of 25 parts per million 
as determined by the method described in paragraph (d)(3) of this 
section.
    (2) The mineral oil may be used only in the processing of jute fiber 
employed in the production of textile bags intended for use in contact 
with the following types of food: Dry grains and dry seeds (for example, 
beans, peas, rice, and lentils); whole root crop vegetables of the types 
identified in 40 CFR 180.34(f); unshelled and shelled nuts (including 
peanuts); and dry animal feed. The finished processed jute fiber shall 
contain no more than 6 percent by weight of residual mineral oil.
    (3) The analytical method for determining ultraviolet absorbance 
limits and pyrene content is as follows:

    I. Apparatus. A. Assorted beakers, separatory funnels fitted with 
tetrafluoroethylene polymer stopcocks, and graduated cylinders.
    B. Volumetric flasks, 200-milliliter.
    C. A chromatographic column made from nominal 1.3 centimeters 
outside diameter x 75 centimeters glass tubing tapered at one end and 
joined to a 2-millimeter-bore tetrafluoroethylene polymer stopcock. The 
opposite end is flanged and joined to a female 24/40 standard taper 
fitting. This provides for accommodating the 500-milliliter reservoir 
described in item I.E below.

[[Page 422]]

    D. A chromatographic column made from nominal 1.7 centimeters 
outside diameter x 115 centimeters glass tubing tapered at one end and 
joined to a 2-millimeter-bore tetrafluoroethylene polymer stopcock. The 
opposite end is flanged and joined to a 2.5 centimeters outside diameter 
x 9.0 centimeters glass tube having a female 24/40 standard taper 
fitting. This provides for accommodating the 500-milliliter reservoir 
described in item I. E below.
    E. A 500-milliliter reservoir having a 24/40 standard taper male 
fitting at bottom and a suitable ball joint at the top for connecting to 
the nitrogen supply. The female fitting of the chromatographic columns 
described in items I. C and D above and the male fitting of the 
reservoir described in this item E should both be equipped with glass 
hooks.

    (Note: Rubber stoppers are not to be used. Stopcock grease is not to 
be used on ground-glass joints in this method.)

    F. A spectrophotometer equipped to automatically record absorbance 
of liquid samples in 1-centimeter pathlength cells in the spectral 
region of 280-400 m[micro] with a spectral slit width of 2 m[micro] or 
less. At an absorbance level of about 0.4, absorbance measurements shall 
be repeatable within 0.01 and accurate within 
0.05. Wavelength measurements shall be repeatable 
with 0.2 m[micro] and accurate within 1.0 m[micro]. Instrument operating conditions are 
selected to realize this performance under dynamic (automatic) recording 
operations. Accuracy of absorbance measurements are determined at 290, 
345, and 400 m[micro], using potassium chromate as the reference 
standard. (National Bureau of Standards Circular 484, Spectrophotometry, 
U.S. Department of Commerce, 1949.)
    G. Two fused quartz cells having pathlengths of 1.000.005 centimeter or better.
    II. Purity of reagents and materials. Reagent-grade chemicals shall 
be used in all tests. It is further specified that each chemical shall 
be tested for purity in accordance with the instruction given under 
``Reagents and Materials'' in III below. In addition, a blank run by the 
procedure shall be made on each purified lot of reagents and materials. 
Unless otherwise indicated, references to water shall be understood to 
mean distilled water.
    III. Reagents and materials-- A. Organic solvents. All solvents used 
throughout the procedure shall meet the specifications and tests 
described in this section III. The isooctane, benzene, cyclohexane, 
nitromethane, and n-hexadecane designated shall pass the following test: 
To the specified quantity of solvent in a 150-milliliter beaker, add 1 
milliliter of purified n-hexadecane and evaporate on the steam bath 
under a stream of nitrogen. Discontinue evaporation when not over 1 
milliliter of residue remains (to the residue from benzene and 
nitromethane add a 10-milliliter portion of purified isooctane, re-
evaporate, and repeat once to insure complete removal of solvent). 
Dissolve the 1 milliliter of n-hexadecane residue in isooctane and make 
to 10-milliliter volume. Determine the absorbance in 1.0-centimeter 
pathlength cells compared to water as reference. The absorbance of the 
solution of solvent residue shall not exceed 0.05 between 280 and 400 
m[micro].
    1. Isooctane (2,2,4-trimethylpentane). Use 240 milliliters for the 
above test. Purify, if necessary, by passage through a column of 
activated silica gel.
    2. Benzene. Use 200 milliliters for the above test. Purify, if 
necessary, by distillation or otherwise.
    3. Cyclohexane. Use 70 milliliters for the above test. Purify, if 
necessary, by distillation, silica gel percolation, or otherwise.
    4. Nitromethane. Use 125 milliliters for the above test. Purify, if 
necessary, by distillation or otherwise.
    5. n-Hexadecane. Determine the absorbance on this solvent directly. 
Purify, if necessary, by silica gel percolation or otherwise.
    B. Other materials--1. Pyrene standard reference. Pyrene, reagent 
grade, melting point range 150-152 [deg]C. (Organic Chemical 3627, 
Eastman Kodak Co., Rochester, N.Y., or equivalent). The standard 
reference absorbance is the absorbance at 334 millimicrons of a standard 
reference solution of pyrene containing a concentration of 1.0 milligram 
per liter in purified isooctane measured against isooctane of the same 
spectral purity in 1.0-centimeter cells. (This absorbance will be 
approximately 0.28.)
    2. Chrysene solution. Prepare a solution at a concentration of 5.0 
milligrams per liter by dissolving 5.0 milligrams of chrysene in 
purified isooctane in a 1-liter volumetric flask. Adjust to volume with 
isooctane.
    3. Nitrogen gas. Water pumped or equivalent purity, cylinder with 
regulator, and valve control flow at 5 p.s.i.
    4. Silica gel. 100-200 mesh (Davison Chemical, Baltimore, Md., Grade 
923, or equivalent), purified and activated by the following procedure: 
Place about 1 kilogram of silica gel in a large column and wash with 
contaminant-free benzene until a 200-milliliter sample of the benzene 
coming off the column will pass the ultraviolet absorption test for 
benzene. This test is performed as stipulated under ``Organic solvents'' 
in A under III above. When the silica gel has been sufficiently cleaned, 
activate the gel before use by placing the 1-kilogram batch in a shallow 
container in a layer no greater than 1 inch in depth and heating in an 
oven (Caution! Explosion Hazard) at 130 [deg]C. for 16 hours, and store 
in a vacuum desiccator. Reheating about once a week is necessary if the 
silica gel is repeatedly removed from the desiccator.
    5. Aluminum oxide (Aluminum Co. of America, Grade F-20, or 
equivalent grade). 80-200 mesh,

[[Page 423]]

purified and activated by the following procedure: Place about 1 
kilogram of aluminum oxide in a large column and wash with contaminant-
free benzene until a 200-milliliter sample of the benzene coming off the 
column will pass the ultraviolet absorption test for benzene. This test 
is performed as stipulated under ``Organic solvents'' in A under III 
above. (Caution! Remove Benzene From Adsorbent Under Vacuum To Minimize 
Explosion Hazard in Subsequent Heating!) When the aluminum oxide has 
been sufficiently cleaned and freed of solvent, activate it before use 
by placing the 1-kilogram batch in a shallow container in a layer no 
greater than 1 inch in depth. Heat in an oven at 130 [deg]C for 16 
hours. Upon removal from heat, store at atmospheric pressure over 80 
percent (by weight) sulfuric acid in a desiccator for at least 36 hours 
before use. This gives aluminum oxide with between 6 to 9.5 percent 
volatiles. This is determined by heating a weighed sample of the 
prepared aluminum oxide at 2,000 [deg]F for 2 hours and then quickly 
reweighing. To insure the proper adsorptive properties of the aluminum 
oxide, perform the following test:
    a. Weigh 50 grams 1 gram of the activated 
aluminum oxide and pack into the chromatographic column (1.3 centimeters 
x 75 centimeters) described under ``Apparatus'' in C under I above. Use 
glass wool at the column exit to prevent the aluminum oxide from passing 
through the column.
    b. Place a 250-milliliter graduated cylinder under the column to 
measure the amount of eluate coming from the column.
    c. Prewet the aluminum oxide by passing 40 milliliters of isooctane 
through the column. Adjust the nitrogen pressure so that the rate of 
descent of the isooctane coming off the column is between 1.5 to 2.5 
milliliters per minute.
    d. Just prior to the last of the isooctane reaching the top of the 
aluminum oxide bed, add 10 milliliters of the isooctane solution 
containing 5.0 milligrams of chrysene per liter.
    e. Continue percolation until the isooctane is just above the 
aluminum oxide. Then add 200 milliliters of a mixture of benzene and 
isooctane (33\1/3\ percent benzene and 66\2/3\ percent isooctane by 
volume) to the reservoir and continue percolation.
    f. Continue percolation, collecting the eluates (40 milliliters of 
the prewet solution, 10 milliliters of the sample solution, and 200 
milliliters of the gradient solution) in the 250-milliliter graduated 
cylinder until the level of the gradient solution is just above the 
aluminum oxide. Add 200 milliliters of the eluting solution of benzene 
and isooctane (90 percent benzene and 10 percent isooctane by volume) to 
the column and continue collecting until a total of 250 milliliters of 
solution has been obtained. This may be discarded. Now begin to collect 
the final eluate.
    g. Place a 100-milliliter graduated cylinder under the column and 
continue the percolation until a 100-milliliter eluate has been 
obtained.
    h. Measure the amount of chrysene in this 100-milliliter fraction by 
ultraviolet analysis. If the aluminum oxide is satisfactory, more than 
80 percent of the original amount of chrysene should be found in this 
fraction. (Note: If the amount of chrysene recovered is less than 80 
percent, the original batch of aluminum oxide should be sieved between 
100-160 mesh. Activation and testing of this sieved batch should 
indicate a satisfactory aluminum oxide for use.)
    IV. Sampling. Precautions must be taken to insure that an 
uncontaminated sample of the mineral oil is obtained since ultraviolet 
absorption is very sensitive to small amounts of extraneous material 
contaminating the sample through careless handling.
    V. Procedure. A. Blank. Before proceeding with the analysis of a 
sample, determine the absorbance of the solvent residues by carrying out 
the procedure without a sample.
    B. Sample. 1. Weigh out 20.0 grams 0.1 gram of 
the mineral oil into a beaker and transfer to a 250-milliliter 
separatory funnel fitted with a tetrafluoroethylene polymer stopcock, 
using enough cyclohexane (25 milliliters) to give a final total volume 
of 50 milliliters (mineral oil plus cyclohexane).
    2. Add 25 milliliters of nitromethane saturated with cyclohexane and 
shake by hand vigorously for 3 minutes. Recover the lower nitromethane 
layer in a 150-milliliter beaker containing 1 milliliter of n-hexadecane 
and evaporate on the steam bath under nitrogen. Repeat the extraction 
four more times, recovering each extract in the 150-milliliter beaker. 
Exercise care not to fill the beaker to such a capacity that solvent 
losses may occur. Evaporate the combined nitromethane extracts to 1 
milliliter of n-hexadecane residue containing the nitromethane-soluble 
mineral oil extractives. (Note: Complete removal of the nitromethane is 
essential. This can be assured by two successive additions of 5 
milliliters of isooctane and reevaporation.)
    3. Remove the beaker from the steam bath and allow to cool.
    4. Weigh 50 grams 1 gram of activated aluminum 
oxide and pack into the chromatographic column (1.3 centimeters x 75 
centimeters) described under ``Apparatus'' in C under I above. (Note: A 
small plug of glass wool is placed at the column exit to prevent the 
aluminum oxide from passing through the column. After adding aluminum 
oxide, tap the column lightly to remove air voids. All percolations 
using aluminum oxide are performed under nitrogen pressure. The 500-
milliliter reservoir described under ``Apparatus'' in E under I above is 
to be used to hold the elution solvents.)

[[Page 424]]

    5. Prewet the column by adding 40 milliliters of isooctane to the 
column. Adjust nitrogen pressure so that rate of descent of the 
isooctane coming off the column is 2.0 to 3.0 milliliters per minute. Be 
careful to maintain the level of solvent in the reservoir to prevent air 
from entering the aluminum oxide bed. New or additional solvent is added 
just before the last portion of the previous solvent enters the bed. To 
minimize possible photo-oxidation effects, the following procedures 
(steps 6 through 18) shall be carried out in subdued light.
    6. Before the last of the isooctane reaches the top of the aluminum 
oxide bed, release the nitrogen pressure and turn off the stopcock on 
the column. Transfer the n-hexadecane residue from the 150-milliliter 
beaker from procedure step 3 above onto the column, using several washes 
of isooctane (total volume of washes should be no greater than 10-15 
milliliters).
    7. Open the stopcock and continue percolation until the isooctane is 
about 1 centimeter above the top of the aluminum oxide bed. Add 200 
milliliters of isooctane to the reservoir, and continue the percolation 
at the specified rate.
    8. Just before the isooctane surface reaches the top of the aluminum 
oxide bed, add 200 milliliters of a mixture of benzene and isooctane 
(33\1/3\ percent benzene and 66\2/3\ percent isooctane by volume) to the 
reservoir, and continue the percolation.
    9. Just before the surface of this mixture reaches the top of the 
aluminum oxide bed, release the nitrogen pressure, turn off the 
stopcock, and discard all the elution solvents collected up to this 
point.
    10. Add to the reservoir 300 milliliters of a mixture of benzene and 
isooctane (90 percent benzene and 10 percent isooctane by volume), place 
a 25-milliliter graduated cylinder under the column, continue the 
percolation until 20 milliliters of eluate has been collected, and then 
discard the eluate.
    11. At this point, place a clean 250-milliliter Erlenmeyer flask 
under the column. Continue the percolation and collect all the remaining 
eluate.
    (Note: Allow the column to drain completely. An increase in the 
nitrogen pressure may be necessary as the last of the solvent comes off 
the column.)
    12. Place 1 milliliter of n-hexadecane into a 150-milliliter beaker. 
Place this onto a steam bath under a nitrogen stream and transfer in 
small portions the eluate from step 11 above. Wash out the Erlenmeyer 
flask with small amounts of benzene and transfer to the evaporation 
beaker. Evaporate until only 1 milliliter of hexadecane residue remains. 
(Note: Complete removal of the benzene is essential. This can be assured 
by two successive additions of 5 milliliters of isooctane and 
reevaporation.)
    13. Remove the beaker from the steam bath and cool.
    14. Place a sample of 113.5 grams activated 100- 200-mesh silica gel 
in a 500-milliliter glass-stoppered Erlenmeyer flask. Add to the silica 
gel 46.2 grams (41 milliliters) of nitromethane. Stopper and shake the 
flask vigorously until no lumps of silica gel are observed and then 
shake occasionally during a period of 1 hour. The resultant 
nitromethane-treated silica gel is 29 weight-percent nitro-methane and 
71 weight-percent silica gel.
    15. Place a small plug of glass wool in the tapered end of the 1.7 
centimeters outside diameter x 115 centimeters column, described under 
``Apparatus'' in D of I above, adjacent to the stopcock to prevent 
silica gel from passing through the stopcock. Pack the nitromethane-
treated silica gel into the column, tapping lightly. The resultant 
silica gel bed should be about 95 centimeters in depth. Place into a 
flask 170 milliliters of isooctane saturated with nitromethane.
    16. Place a 100-milliliter graduated cylinder under the column and 
transfer the residue from the beaker in procedure step 13 above with 
several washes of the 170 milliliters of isooctane, saturated with 
nitromethane, onto the top of the column. (Total volume of washes should 
be no greater than 10 to 15 milliliters.) Permit isooctane solution to 
enter the silica gel bed until the liquid level is at the top bed level. 
Place the remaining amount of the 170 milliliters of isooctane, 
saturated with nitromethane, in the reservoir above the bed for 
percolation through the silica gel. Apply nitrogen pressure to the top 
of the column, adjusting the pressure so that the isooctane is collected 
at the rate of 2.5 to 3.5 milliliters per minute, and percolate 
isooctane through the bed until a quantity of 75.0 milliliters of eluate 
is collected. Discard the 75 milliliters of eluate. Turn off the 
stopcock and add 250 milliliters of benzene to the reservoir above the 
bed. Use a 400-milliliter beaker to collect the remaining eluate.
    17. Open the stopcock, renew the pressure, and percolate the 
remaining isooctane and benzene through the column eluting the remaining 
aromatics. Transfer the eluate in small portions from the 400 milliliter 
beaker to a 150-milliliter beaker containing 1 milliliter of n-
hexadecane and evaporate on the steam bath under nitrogen. Rinse the 
400-milliliter beaker well with small portions of isooctane to obtain a 
complete transfer.
    (Note: Complete removal of the nitromethane and benzene is 
essential. This can be assured by successive additions of 5 milliliters 
of isooctane and reevaporation.)
    18. Transfer the residue with several washes of isooctane into a 
200-milliliter volumetric flask. Add isooctane to mark.

[[Page 425]]

    19. Record the spectrum of the sample solution in a 1-centimeter 
cell compared to isooctane from 270 to 400 m[micro]. After making 
necessary corrections in the spectrum for cell differences and for the 
blank absorbance, record the maximum absorbance in each of the 
wavelength intervals (m[micro]), 280-299, 300-319, 320-359, 360-400.
    a. If the spectrum then shows no discernible peak corresponding to 
the absorbance maximum of the pyrene reference standard solution at 334 
m[micro], the maximum absorbances in the respective wavelength intervals 
recorded shall not exceed those prescribed in paragraph (d)(1)(ii) of 
this section.
    b. If such a peak is evident in the spectrum of the sample solution, 
and the spectrum as a whole is not incompatible with that of a pyrene 
contaminant yielding such a peak of the observed absorbance, calculate 
the concentration of pyrene that would yield this peak (334 m) by the 
base-line technique described in ASTM method E169-63 (Reapproved 1981), 
``Standard Recommended Practices for General Techniques of Ultraviolet 
Quantitative Analysis,'' which is incorporated by reference. The 
availability of this incorporation by reference is given in paragraph 
(b)(1)(i) of this section. Correct each of the maximum absorbances in 
the respective specified wavelength intervals by subtracting the 
absorbance due to pyrene, determined as follows:
[GRAPHIC] [TIFF OMITTED] TR01JA93.407

where:

Cp=Calculated concentration of pyrene in sample solution;
Sp=Concentration of pyrene reference standard solution in same units of 
concentration;
Sa=Absorbance of pyrene reference standard solution at wavelength of 
maximum absorbance of sample solution in the respective specified 
wavelength intervals.
    Also calculate the pyrene content of the oil sample in parts per 
million as follows:
[GRAPHIC] [TIFF OMITTED] TR01JA93.408

where:
C=Calculated concentration of pyrene in milligrams per liter of sample 
solution.
    c. The pyrene content so determined shall not exceed 25 p.p.m. The 
maximum absorbances corrected for pyrene content as described in this 
step 19 for each of the specified wavelength intervals shall not exceed 
the limits prescribed in paragraph (d)(1)(ii) of this section.
    d. If the spectrum as a whole of the sample solution is in any 
respect clearly incompatible with the presence of pyrene as the source 
of the peak at 334 m[micro], then the maximum absorbances in the 
respective wavelength intervals without correction for any assumed 
pyrene content shall not exceed the limits prescribed in paragraph 
(d)(1)(ii) of this section.

[42 FR 14609, Mar. 15, 1977, as amended at 47 FR 11847, Mar. 19, 1982; 
49 FR 10112, Mar. 19, 1984; 54 FR 24898, June 12, 1989]





Additives that reference this regulation:


Source: U.S. Code of Federal Regulations - CFR Title 21, Part 178, Section 3620


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