ASTM D1439-03(2008)e1
(Test Method)Standard Test Methods for Sodium Carboxymethylcellulose
Standard Test Methods for Sodium Carboxymethylcellulose
SIGNIFICANCE AND USE
Moisture analysis (along with purity) is used to calculate the amount of active polymer in the material and must be considered when determining the amount of sodium carboxymethylcellulose to use in various formulations.
SCOPE
1.1 These test methods cover the testing of sodium carboxymethylcellulose.
1.2 The test procedures appear in the following order:
Sections Moisture4-9 Degree of Etherification: Test Method A—Acid Wash10-17 Test Method B—Nonaqueous Titration10, 12, 18-23 Viscosity24-30 Purity31-38 Sodium Glycolate39-47 Sodium Chloride48-55 Density56-62
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see 15.1 and 20.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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´1
Designation: D1439 − 03(Reapproved 2008)
Standard Test Methods for
Sodium Carboxymethylcellulose
This standard is issued under the fixed designation D1439; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Editorial changes were made in Sections 11, 12, 15.5, and 31.1 in June 2008.
1. Scope conform to the specifications of the Committee on Analytical
Reagents of the American Chemical Society , where such
1.1 These test methods cover the testing of sodium car-
specifications are available. Other grades may be used, pro-
boxymethylcellulose.
vided it is first ascertained that the reagent is of sufficiently
1.2 The test procedures appear in the following order:
high purity to permit its use without lessening the accuracy of
Sections
the determination.
Moisture 4–9
Degree of Etherification: 3.2 Unless otherwise indicated, references to water shall be
Test Method A—Acid Wash 10–17
understood to mean distilled water.
Test Method B—Nonaqueous Titration 10, 12, 18–23
Viscosity 24–30
MOISTURE
Purity 31–38
Sodium Glycolate 39–47
Sodium Chloride 48–55
4. Scope
Density 56–62
4.1 Thistestmethodcoversthedeterminationofthevolatile
1.3 The values stated in SI units are to be regarded as the
content of sodium carboxymethylcellulose.
standard. The values given in parentheses are for information
4.2 The results of this test are used for calculating the total
only.
solids in the sample; and, by common usage, all materials
1.4 This standard does not purport to address all of the
volatile at this test temperature are designated as moisture.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
5. Significance and Use
priate safety and health practices and determine the applica-
5.1 Moistureanalysis(alongwithpurity)isusedtocalculate
bility of regulatory limitations prior to use. For specific hazard
the amount of active polymer in the material and must be
statements, see 15.1 and 20.
consideredwhendeterminingtheamountofsodiumcarboxym-
2. Referenced Documents
ethylcellulose to use in various formulations.
2.1 ASTM Standards:
6. Apparatus
D1347 Test Methods for Methylcellulose (Withdrawn
2003) 6.1 Oven—Gravityconvectionoven,capableofmaintaining
E1Specification for ASTM Liquid-in-Glass Thermometers a temperature of 105 6 3°C.
6.2 Weighing Bottles, low-form, 50-mm inside diameter by
3. Purity of Reagents
30-mm height, or equivalent.
3.1 Reagent grade chemicals shall be used in all tests.
6.3 Analytical Balance.
Unlessotherwiseindicated,itisintendedthatallreagentsshall
7. Procedure
These test methods are under the jurisdiction of ASTM Committee D01 on
Paint and Related Coatings, Materials, and Applications and are the direct
7.1 Weigh3to5gofthe sample to the nearest 0.001 g in a
responsibility of Subcommittee D01.36 on Cellulose and Cellulose Derivatives.
tared and covered weighing bottle.
Current edition approved June 1, 2008. Published June 2008. Originally
approved in 1956. Last previous edition approved in 2003 as D1439–03. DOI:
10.1520/D1439-03R08E01.
2 4
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Reagent Chemicals, American Chemical Society Specifications, American
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Standards volume information, refer to the standard’s Document Summary page on listed by the American Chemical Society, see Analar Standards for Laboratory
the ASTM website. Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
The last approved version of this historical standard is referenced on and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
www.astm.org. MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
D1439 − 03 (2008)
7.2 Place the bottle in an oven at 105°C for 2 h with the 13.2 Buchner Funnel, 75-mm, fitted with a 70-mm fine-
cover removed. Cool the bottle in a desiccator, replace the texture, heavy-duty filter paper. A 60-mm medium-porosity,
cover, and weigh. fritted glass funnel may also be used.
7.3 Replace the sample in the oven for 30 min, cool, and 13.3 Drying Oven, maintained at 105°C.
reweigh.
14. Reagents
7.4 Continue this procedure to a mass loss of not more than
5 mg for 30 min drying time.
14.1 Diphenylamine Reagent—Dissolve 0.5 g of diphe-
nylamine in 120 mL of sulfuric acid (H SO , 9+2). The
2 4
8. Calculation
reagent should be essentially water-white. It will give a deep
blue coloration with traces of nitrate or other oxidizing agents.
8.1 Calculate the percent moisture, M, as follows:
14.2 Ethyl Alcohol (95 volume %)—Denaturedethylalcohol
M 5 ~A/B! 3100 (1)
conformingtoeitherFormula2B,3A,or30oftheU.S.Bureau
where:
of Internal Revenue.
A = mass loss on heating, g, and
14.3 Ethyl Alcohol (80 % by volume)—Dilute 840 mL of
B = sample used, g.
Formula 2B, 3A, or 30 denatured alcohol to 1 L with water.
9. Precision and Bias
14.4 Hydrochloric Acid, Standard (HCl, 0.3 to 0.5 N).
9.1 Precision—Statistical analysis of interlaboratory repro-
14.5 Methanol, anhydrous.
ducibilitytestresultsonsamplescontaining2to10%moisture
14.6 Nitric Acid (sp gr 1.42)—Concentrated nitric acid
indicates a precision of 60.2% absolute at the 95% confi-
(HNO ).
dence level.
14.7 Sodium Hydroxide, Standard Solution(0.3 to 0.5 N)—
9.2 Bias—No justifiable statement can be made on the bias
Prepare and standardize a 0.3 to 0.5 N solution of sodium
of the procedure for measuring moisture because no suitable
hydroxide (NaOH).
reference material exists.
14.8 Sulfuric Acid (9 + 2)—Carefullymix9volumesH SO
2 4
DEGREE OF ETHERIFICATION
with 2 volumes of water.
10. Scope
15. Procedure
10.1 These test methods cover the determination of the
15.1 Weigh approximately4gofthe sample into a 250-mL
degree of etherification (D.E.) of sodium carboxymethylcellu-
beakerandadd75mLofethylalcohol(95%).Stirthemixture
lose.
withanair–drivenstirreruntilagoodslurryisobtained.Add5
10.2 Two test methods are included as follows:
mLof HNO , while agitating, and continue agitation for 1 to 2
10.2.1 Test Method A (Acid Wash), for crude grades of
min. Heat the slurry and boil for 5 min. (Warning—Exercise
sodium carboxymethylcellulose with degrees of etherification
care to avoid fire.) Remove the heat and continue agitation for
up to 0.85. Above 0.85 degree of etherification, slightly low
10 to 15 min.
results may be obtained.
15.2 Decant the supernatant liquid through the filter and
10.2.2 Test Method B (Nonaqueous Titration), for purified
transfer the precipitate to the filter with 50 to 100 mL of ethyl
grades of sodium carboxymethylcellulose of all degrees of
alcohol (95%).Wash the precipitate with ethyl alcohol (80%)
etherification. It is not applicable to the crude grades.
that has been heated to 60°C, until all of the acid has been
removed.
11. Significance and Use
15.3 Test for the removal of acid and salts (ash) by mixing
11.1 These test methods determine the amount of substitu-
adropoftheacidcarboxymethylcelluloseslurryfromthefilter
ent groups added to the cellulose backbone. The level can
with a drop of diphenylamine reagent on a white spot plate.A
greatly affect solution properties, rheology, viscosity,
bluecolorindicatesthepresenceofnitrateandthenecessityfor
hygroscopicity,salttolerance,andmanyotherpropertiesofthe
further washing. If the first drop of reagent does not produce a
polymer.
blue color, further drops should be added until an excess of
Test Method A—Acid Wash reagentisknowntobepresent,notingthecoloraftereachdrop.
Four to six washings will usually suffice to give a negative test
12. Summary of Test Method
for nitrate.
12.1 The water-soluble sodium carboxymethylcellulose is
15.4 Finally, wash the precipitate with a small amount of
converted to the insoluble acid form, purified by washing,
anhydrousmethanolanddrawairthroughituntilthealcoholis
dried, and then a weighed sample is reconverted to the sodium
completely removed. Transfer the precipitate to a glass or
salt with a measured excess of sodium hydroxide.
aluminum weighing dish provided with a cover. Heat the
uncovereddishonasteambathuntiltheodorofalcoholcanno
13. Apparatus
longer be detected (in order to avoid fires due to methanol
13.1 Stirrer, air-driven. fumes in the oven), then dry the dish and contents, uncovered
´1
D1439 − 03 (2008)
for3hat 105°C. Place the cover on the dish and cool to room 19.1.1 Discard the aqueous potassium chloride solution,
temperature in a desiccator. then rinse and fill with the calomel electrode solution as
described in 20.2.
15.5 The sulfate ash content of the sample at this point
19.1.2 Add a few crystals of potassium chloride and silver
should be less than 0.5% when determined on 0.5 g of the
chloride or silver oxide to the electrode.
sample by the procedure given in theAsh as Sulfate section of
Test Methods D1347. If the ash content is greater than 0.5%,
19.2 Buret, micro, 10-mL capacity.
rewash the sample with ethyl alcohol (80%). If necessary,
repeat the procedure described in 15.1 – 15.4.
20. Reagents
15.6 Weigh, to the nearest 0.01 g, about 1 to 1.5 g of the
20.1 Acetic Acid, glacial.
dried acid carboxymethylcellulose (depending on the normal-
20.2 Calomel Electrode Solution—Add2gof potassium
ity of the acid and base to be used) into a 500-mLErlenmeyer
chloride(KCl)and2gofsilverchloride(AgCl)orsilveroxide
flask. Add 100 mL of water and 25.00 mL of 0.3 to 0.5 N
(Ag O) to 100 mL of methanol and shake thoroughly to
NaOHsolution,whilestirring.Heatthesolutiontoboiling,and
saturate. Use the supernatant liquid.
boil for 15 to 30 min.
15.7 TitratetheexcessNaOH,whilethesolutionishot,with 20.3 1,4-Dioxane.
the 0.3 to 0.5 N HCl to a phenolphthalein end point.
20.4 Perchloric Acid (0.1 N)—Add 9 mL of concentrated
perchloric acid (HClO , 70% to 1 L of dioxane, with stirring
16. Calculation
(Warning—The solution of perchloric acid in dioxane should
16.1 Calculate the degree of etherification, G, as follows:
never be heated or allowed to evaporate.). Store in an amber
A 5 BC 2 DE /F (2) glass bottle. Any slight discoloration that appears on standing
~ !
may be disregarded.
G 50.162A/ 1 20.0584A (3)
~ !
20.4.1 Standardize the solution as follows: Dry potassium
where:
acid phthalate for2hat 120°C. Weigh 2.5 g to the nearest
A = milliequivalents of acid consumed per gram of
0.0001 g into a 250-mL volumetric flask. Add glacial acetic
sample,
acid, shake to dissolve, and then make up to volume and mix
B = NaOH solution added, mL,
thoroughly. Pipet 10 mLinto a 100-mLbeaker and add 50 mL
C = normality of the NaOH solution,
of acetic acid. Place on a magnetic stirrer and insert the
D = HCl required for titration of the excess NaOH, mL,
electrodes of the pH meter.Add nearly the required amount of
E = normality of the HCl,
HClO from a buret, then decrease the increments to 0.05 mL
F = acid carboxymethylcellulose used, g,
as the end point is approached. Record the millilitres of titrant
162 = gram molecular mass of the anhydroglucose unit of
versus millivolts, and continue the titration a few millilitres
cellulose, and
beyond the end point. Plot the titration curve and read the
58 = netincreaseinmolecularmassofanhydroglucoseunit
volume of titrant at the inflection point. Calculate the
for each carboxymethyl group substituted.
normality, N, as follows:
17. Precision and Bias
N 5 ~A 310 31000!/~B 3204.22 3250! (4)
17.1 Precision—Statistical analysis of intralaboratory (re-
where:
peatability) test results indicates a precision of 60.04 D.E.
A = potassium acid phthalate used, g,
units at the 95% confidence level.
B = HClO added, mL,
204.22 = gram molecular mass of potassium acid phthalate,
17.2 Bias—Nojustifiablestatementcanbemadeonthebias
10 = potassium acid phthalate solution added, mL, and
oftheprocedureformeasuringdegreeofetherificationbecause
250 = glacial acetic acid used to dissolve potassium acid
no suitable reference material exists.
phthalate, mL.
Test Method B—Nonaqueous Titration
20.5 Potassium Acid Phthalate, primary standard, National
Institute of Standards and Technology Standard Sample No.
18. Summary of Test Methods
84.
18.1 This measurement is based upon a nonaqueous acid-
base titration. The sample is refluxed with glacial acetic acid,
21. Procedure
and the resulting sodium acetate is titrated with a standard
21.1 Weigh0.2gofthesample,tothenearest0.0001g,into
solution of perchloric acid in dioxane, to a potentiometric end
a 250-mL Erlenmeyer flask with ground-glass joint. Add 75
point. Impurities containing alkaline sodium will also be
mL of acetic acid, connect to a water-cooled condenser, and
titrated under these conditions. Sodium chloride does not
reflux gently on a hot plate for 2 h.
interfere.
21.2 Cool,andtransferthesolutiontoa250-mLbeakerwith
19. Apparatus
the aid of 50 mL of acetic acid. Place on the magnetic stirrer
19.1 pH Meter,equippedwithastandardglasselectrodeand and titrate to a potentiometric end point with 0.1 N HClO in
a calomel electrode modified as follows: accordance with 20.4.
´1
D1439 − 03 (2008)
TABLE 1 Viscometer Spindles Required for Given Speeds
22. Calculation
Viscosity
22.1 Calculate the degree of etherification, H, as follows Spindle Speed,
Range, Scale Factor
No. rpm
(Note 1):
cP
10 to 100 1 60 100 1
M 5 AN 3100 / G 3 100 2 B (5)
~ ! ~ ~ !!
100 to 200 1 30 100 2
H 50.162 M/ 1.000 2 0.080 M (6) 200 to 1000 2 30 100 10
~ ~ !!
1000 to 4000 3 30 100 40
where:
4000 to 10000 4 30 100 200
M = milliequivalents of acid consumed per gram of
sample,
A = HClO added, mL,
25. Significance and Use
N = normality of HClO ,
G = sample used, g,
25.1 This test method determines the relative ability of the
B = percent moisture, determined on a separate sample, in
polymer to thicken water. This is the primary function of
accordance with Sections4–7,
sodium carboxymethylcellulose.
162 = gram molecular mass of an anhydroglucose unit of
cellulose, and
26. Apparatus
80 = net increase in molecular mass of an anhydroglucose
26.1 Viscometer, Brookfield type.
unit for each sodium carboxymethyl group added.
NOTE 1—The result calculated in accordance with Section 18 includes
26.2 Container—Glass jar, approximately 64-mm (2 ⁄2-in.)
the alkaline sodium from sodium glycolate; however, if the latter is less
in diameter and 152 mm (6 in.) deep, unconstricted at
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
e1
Designation:D1439–97 Designation:D1439–03(Reapproved2008)
Standard Test Methods for
Sodium Carboxymethylcellulose
This standard is issued under the fixed designation D 1439; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
e NOTE—Editorial changes were made in Sections 11, 12, 15.5, and 31.1 in June 2008.
1. Scope
1.1 These test methods cover the testing of sodium carboxymethylcellulose.
1.2 The test procedures appear in the following order:
Sections
Moisture 4-9
Degree of Etherification:
Test Method A—Acid Wash 10-17
Test Method B—Nonaqueous Titration10, 11, 10, 12, 18-23
Test Method B—Nonaqueous Titration 10, 12, 18-23
Viscosity 24-30
Purity 31-38
Sodium Glycolate 39-47
Sodium Chloride 48-55
Density 56-62
1.3 The values stated in inch-poundSI units are to be regarded as the standard. The values given in parentheses are for
information only.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use. For specific hazard statements, see Note 1 and Note 2For specific hazard statements, see 15.1 and 20.
2. Referenced Documents
2.1 ASTM Standards:
D 1347 Test Methods for Methylcellulose
E 1 Specification for ASTM Liquid-in-Glass Thermometers
3. Purity of Reagents
3.1 Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform
to the specifications of the Committee on Analytical Reagents of the American Chemical Society , where such specifications are
available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use
without lessening the accuracy of the determination.
3.2 Unless otherwise indicated, references to water shall be understood to mean distilled water.
MOISTURE
4. Scope
4.1 This test method covers the determination of the volatile content of sodium carboxymethylcellulose.
4.2 The results of this test are used for calculating the total solids in the sample; and, by common usage, all materials volatile
at this test temperature are designated as moisture.
These test methods are under the jurisdiction ofASTM Committee D-1D01 on Paint and Related Coatings, Materials, andApplications and are the direct responsibility
of Subcommittee D01.36 on Cellulose and Cellulose Derivatives.
Current edition approved Nov. 10, 1997.June 1, 2008. Published July 1998.June 2008. Originally published as D1439–56T.approved in 1956. Last previous edition
D1439–94.approved in 2003 as D 1439 – 03.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book ofASTM Standards
, Vol 06.03.volume information, refer to the standard’s Document Summary page on the ASTM website.
Annual Book of ASTM Standards, Vol 14.03.
Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by
the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National
Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
e1
D1439–03 (2008)
5. Significance and Use
5.1 Moisture analysis (along with purity) is used to calculate the amount of active polymer in the material and must be
considered when determining the amount of sodium carboxymethylcellulose to use in various formulations.
6. Apparatus
6.1 Oven—Gravity convection oven, capable of maintaining a temperature of 105 6 3°C.
6.2 Weighing Bottles, low-form, 50-mm inside diameter by 30-mm height, or equivalent.
6.3 Analytical Balance.
7. Procedure
7.1 Weigh3to5gofthe sample to the nearest 0.001 g in a tared and covered weighing bottle.
7.2 Place the bottle in an oven at 105°C for 2 h with the cover removed. Cool the bottle in a desiccator, replace the cover, and
weigh.
7.3 Replace the sample in the oven for 30 min, cool, and reweigh.
7.4 Continue this procedure to a mass loss of not more than 5 mg for 30 min drying time.
8. Calculation
8.1 Calculate the percent moisture, M, as follows:
M 5 ~A/B! 3 100 (1)
where:
A = mass loss on heating, g, and
B = sample used, g.
9. Precision and Bias
9.1 Precision—Statistical analysis of interlaboratory reproducibility test results on samples containing 2 to 10 % moisture
indicates a precision of 60.2 % absolute at the 95 % confidence level.
9.2 Bias—No justifiable statement can be made on the bias of the procedure for measuring moisture because no suitable
reference material exists.
DEGREE OF ETHERIFICATION
10. Scope
10.1 These test methods cover the determination of the degree of etherification (D.E.) of sodium carboxymethylcellulose.
10.2 Two test methods are included as follows:
10.2.1 Test Method A (Acid Wash), for crude grades of sodium carboxymethylcellulose with degrees of etherification up to
0.85. Above 0.85 degree of etherification, slightly low results may be obtained.
10.2.2 Test Method B (Nonaqueous Titration), for purified grades of sodium carboxymethylcellulose of all degrees of
etherification. It is not applicable to the crude grades. Test Method A—Acid Wash
11. Summary of Test Method
11.1The water-soluble sodium carboxymethylcellulose is converted to the insoluble acid form, purified by washing, dried, and
then a weighed sample is reconverted to the sodium salt with a measured excess of sodium hydroxide.
12.Significance and Use
12.1These test methods determine the amount of substituent groups added to the cellulose backbone.The level can greatly affect
solution properties, rheology, viscosity, hygroscopicity, salt tolerance, and many other properties of the polymer.
11.1 These test methods determine the amount of substituent groups added to the cellulose backbone. The level can greatly
affect solution properties, rheology, viscosity, hygroscopicity, salt tolerance, and many other properties of the polymer.
Test Method A—Acid Wash
12. Summary of Test Method
12.1 The water-soluble sodium carboxymethylcellulose is converted to the insoluble acid form, purified by washing, dried, and
then a weighed sample is reconverted to the sodium salt with a measured excess of sodium hydroxide.
13. Apparatus
13.1 Stirrer, air-driven.
e1
D1439–03 (2008)
13.2 Buchner Funnel,75-mm,fittedwitha70-mmfine-texture,heavy-dutyfilterpaper.A60-mmmedium-porosity,frittedglass
funnel may also be used.
13.3 Drying Oven, maintained at 105°C.
14. Reagents
14.1 Diphenylamine Reagent—Dissolve 0.5 g of diphenylamine in 120 mLof sulfuric acid (H SO , 9 + 2).The reagent should
2 4
be essentially water-white. It will give a deep blue coloration with traces of nitrate or other oxidizing agents.
14.2 Ethyl Alcohol (95 volume %) —Denatured ethyl alcohol conforming to either Formula 2B, 3A, or 30 of the U. S. Bureau
of Internal Revenue.
14.3 Ethyl Alcohol (80 % by volume)—Dilute 840 mL of Formula 2B, 3A, or 30 denatured alcohol to 1 L with water.
14.4 Hydrochloric Acid, Standard (HCl, 0.3 to 0.5 N).
14.5 Methanol, anhydrous.
14.6 Nitric Acid (sp gr 1.42)—Concentrated nitric acid (HNO ).
14.7 Sodium Hydroxide, Standard Solution (0.3to0.5 N)—Prepareandstandardizea0.3to0.5 Nsolutionofsodiumhydroxide
(NaOH).
14.8 Sulfuric Acid (9 + 2) —Carefully mix 9 volumes H SO with 2 volumes of water.
2 4
15. Procedure
15.1 Weigh approximately4gofthe sample into a 250-mLbeaker and add 75 mLof ethyl alcohol (95 %). Stir the mixture with
an air–driven stirrer until a good slurry is obtained. Add 5 mL of HNO , while agitating, and continue agitation for 1 to 2 min.
Heat the slurry and boil for 5 min. (Warning—See Note 1.) Remove the heat and continue agitation for 10 to 15 min.
NOTE1—Warning:Exercise care to avoid fire. —Exercise care to avoid fire.) Remove the heat and continue agitation for 10 to 15 min.
15.2 Decant the supernatant liquid through the filter and transfer the precipitate to the filter with 50 to 100 mL of ethyl alcohol
(95 %). Wash the precipitate with ethyl alcohol (80 %) that has been heated to 60°C, until all of the acid has been removed.
15.3 Test for the removal of acid and salts (ash) by mixing a drop of the acid carboxymethylcellulose slurry from the filter with
a drop of diphenylamine reagent on a white spot plate.Ablue color indicates the presence of nitrate and the necessity for further
washing.Ifthefirstdropofreagentdoesnotproduceabluecolor,furtherdropsshouldbeaddeduntilanexcessofreagentisknown
to be present, noting the color after each drop. Four to six washings will usually suffice to give a negative test for nitrate.
15.4 Finally, wash the precipitate with a small amount of anhydrous methanol and draw air through it until the alcohol is
completely removed.Transfer the precipitate to a glass or aluminum weighing dish provided with a cover. Heat the uncovered dish
on a steam bath until the odor of alcohol can no longer be detected (in order to avoid fires due to methanol fumes in the oven),
thendrythedishandcontents,uncoveredfor3hat105°C.Placethecoveronthedishandcooltoroomtemperatureinadesiccator.
15.5 The sulfate ash content of the sample at this point should be less than 0.5 % when determined on 0.5 g of the sample by
the procedure given in the Ash as Sulfate section of Test Methods D 1347. If the ash content is greater than 0.5 %, rewash the
sample with ethyl alcohol (80 %). If necessary, repeat the procedure described in 13.1-13.315.1-15.4 to 13.4. .
15.6 Weigh, to the nearest 0.01 g, about 1 to 1.5 g of the dried acid carboxymethylcellulose (depending on the normality of the
acid and base to be used) into a 500-mL Erlenmeyer flask. Add 100 mL of water and 25.00 mL of 0.3 to 0.5 N NaOH solution,
while stirring. Heat the solution to boiling, and boil for 15 to 30 min.
15.7 Titrate the excess NaOH, while the solution is hot, with the 0.3 to 0.5 N HCl to a phenolphthalein end point.
16. Calculation
16.1 Calculate the degree of etherification, G, as follows:
A 5 ~BC – DE!/F (2)
G 5 0.162A/ 1– 0.0584A (3)
~ !
where:
A = milliequivalents of acid consumed per gram of sample,
B = NaOH solution added, mL,
C = normality of the NaOH solution,
D = HCl required for titration of the excess NaOH, mL,
E = normality of the HCl,
F = acid carboxymethylcellulose used, g,
162 = gram molecular mass of the anhydroglucose unit of cellulose, and
58 = net increase in molecular mass of anhydroglucose unit for each carboxymethyl group substituted.
17. Precision and Bias
17.1 Precision—Statistical analysis of intralaboratory (repeatability) test results indicates a precision of 6 0.04 D.E. units at the
95 % confidence level.
e1
D1439–03 (2008)
17.2 Bias—No justifiable statement can be made on the bias of the procedure for measuring degree of etherification because
no suitable reference material exists.
Test Method B—Nonaqueous Titration
18. Summary of Test Methods
18.1 This measurement is based upon a nonaqueous acid-base titration. The sample is refluxed with glacial acetic acid, and the
resulting sodium acetate is titrated with a standard solution of perchloric acid in dioxane, to a potentiometric end point. Impurities
containing alkaline sodium will also be titrated under these conditions. Sodium chloride does not interfere.
19. Apparatus
19.1 pH Meter, equipped with a standard glass electrode and a calomel electrode modified as follows:
19.1.1 Discard the aqueous potassium chloride solution, then rinse and fill with the calomel electrode solution as described in
20.2.
19.1.2 Add a few crystals of potassium chloride and silver chloride or silver oxide to the electrode.
19.2 Buret, micro, 10-mL capacity.
20. Reagents
20.1 Acetic Acid, glacial.
20.2 CalomelElectrodeSolution—Add2gofpotassiumchloride(KCl)and2gofsilverchloride(AgCl)orsilveroxide(Ag O)
to 100 mL of methanol and shake thoroughly to saturate. Use the supernatant liquid.
20.3 1,4-Dioxane.
20.4 Perchloric Acid (0.1 N)—Add 9 mL of concentrated perchloric acid (HClO , 70 % to 1 L of dioxane, with stirring
(Warning—See Note 2). Store in an amber glass bottle. Any slight discoloration that appears on standing may be disregarded.
NOTE2—Warning:The solution of perchloric acid in dioxane should never be heated or allowed to evaporate. —The solution of perchloric acid in
dioxane should never be heated or allowed to evaporate.). Store in an amber glass bottle. Any slight discoloration that appears on standing may be
disregarded.
20.4.1 Standardize the solution as follows: Dry potassium acid phthalate for2hat 120°C. Weigh 2.5 g to the nearest 0.0001
gintoa250-mLvolumetricflask.Addglacialaceticacid,shaketodissolve,andthenmakeuptovolumeandmixthoroughly.Pipet
10 mL into a 100-mL beaker and add 50 mL of acetic acid. Place on a magnetic stirrer and insert the electrodes of the pH meter.
Add nearly the required amount of HClO from a buret, then decrease the increments to 0.05 mL as the end point is approached.
Record the millilitres of titrant versus millivolts, and continue the titration a few millilitres beyond the end point. Plot the titration
curve and read the volume of titrant at the inflection point. Calculate the normality, N, as follows:
N 5 ~A 3 10 3 1000!/~B 3 204.22 3 250! (4)
where:
A = potassium acid phthalate used, g,
B = HClO added, mL,
204.22 = gram molecular mass of potassium acid phthalate,
10 = potassium acid phthalate solution added, mL, and
250 = glacial acetic acid used to dissolve potassium acid phthalate, mL.
20.5 Potassium Acid Phthalate, primary standard, National Institute of Standards and Technology Standard Sample No. 84.
21. Procedure
21.1 Weigh 0.2 g of the sample, to the nearest 0.0001 g, into a 250-mL Erlenmeyer flask with ground-glass joint. Add 75 mL
of acetic acid, connect to a water-cooled condenser, and reflux gently on a hot plate for 2 h.
21.2 Cool, and transfer the solution to a 250-mL beaker with the aid of 50 mL of acetic acid. Place on
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