ASTM D3516-89(2019)e1
(Test Method)Standard Test Methods for Ashing Cellulose
Standard Test Methods for Ashing Cellulose
SIGNIFICANCE AND USE
4.1 Ash content gives an estimation of the inorganic content of cellulose samples. The presence of high levels of ash can be expected to be detrimental to the process of making cellulose derivatives. It also provides a rough estimate of silica content which can have a significant effect on the performance of filters in cellulose derivative manufacturing facilities.
SCOPE
1.1 These test methods cover four ashing methods for cellulose. These are intended for use on unbleached and bleached cellulose in sheeted or bulk fiber form. Each one of the test methods has advantages, so that preference applications exist for all four.
1.2 The test methods appear as follows:
Sections
Test Method A—Ash in Cellulose at 575°C
6 to 11
Test Method B—Sulfated Ash in Cellulose at 575°C
12 to 17
Test Method C—Ashing Cellulose by Schoniger Oxidation
18 to 22
Test Method D—Wet Ashing of Cellulose for Inorganics
23 to 29
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see 20.6.1.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: D3516 − 89 (Reapproved 2019)
Standard Test Methods for
Ashing Cellulose
This standard is issued under the fixed designation D3516; 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.
ε NOTE—Editorial updates made to Section 2 and Footnote 4 in December 2019.
1. Scope D1348 Test Methods for Moisture in Cellulose (Withdrawn
2017)
1.1 These test methods cover four ashing methods for
cellulose. These are intended for use on unbleached and
3. Summary of Test Methods
bleached cellulose in sheeted or bulk fiber form. Each one of
3.1 Test Method A, Ash in Cellulose at 575°C—This test
the test methods has advantages, so that preference applica-
method measures the ash content of cellulose, which is defined
tions exist for all four.
for this test as the residue remaining after ignition at 575 6
1.2 The test methods appear as follows:
25°C until all carbon has been burned off. It is the simplest of
Sections
the four test methods for the determination of ash content only,
Test Method A—Ash in Cellulose at 575°C 6 to 11
and it should not be considered as a standard preparative
Test Method B—Sulfated Ash in Cellulose at 575°C 12 to 17
Test Method C—Ashing Cellulose by Schoniger Oxidation 18 to 22 procedure for elemental analysis.
Test Method D—Wet Ashing of Cellulose for Inorganics 23 to 29
NOTE 1—The ash content at this ignition temperature is a reasonable
1.3 The values stated in SI units are to be regarded as the
measure of the mineral salts and inorganic foreign matter in the cellulose.
standard. The values given in parentheses are for information
The weight of ash obtained varies with the temperature of ignition. Higher
temperatures(850°C)willconvertcalciumcarbonateandothercarbonates
only.
to the oxides and thus give lower values for ash. The composition of ash
1.4 This standard does not purport to address all of the
may vary with the pulping process employed for manufacture, which
safety concerns, if any, associated with its use. It is the limits the significance of the ash determination in absolute terms.
responsibility of the user of this standard to establish appro-
3.2 Test Method B, Sulfated Ash in Cellulose at 575°C—In
priate safety, health, and environmental practices and deter-
this ashing procedure the metal salts are converted to sulfates
mine the applicability of regulatory limitations prior to use.
by treatment with sulfuric acid and ignition at 575 6 25°C to
For a specific hazard statement, see 20.6.1.
overcome limitations of Test Method A. It should not be
1.5 This international standard was developed in accor-
considered as a standard preparative test method for elemental
dance with internationally recognized principles on standard-
analysis.
ization established in the Decision on Principles for the
NOTE 2—Conventional dry ashing at high temperature (over 850°C)
Development of International Standards, Guides and Recom-
results in loss of carbon dioxide from metal carbonates, decomposition of
mendations issued by the World Trade Organization Technical
magnesiumsulfate,andlossofsodiumsalts.Ashingatlowertemperatures
Barriers to Trade (TBT) Committee.
(575°C) gives a better estimate of the inorganic impurities, but has the
disadvantage of requiring a long ignition time and also the heat produced
by the burning pulp can raise the temperature far above 575°C for a short
2. Referenced Documents
period of time, converting calcium carbonate to the oxide in varying
2.1 ASTM Standards: amounts.The sulfated ash method overcomes these objectionable features
and has additional advantages. It is relatively insensitive to ignition time.
D1193 Specification for Reagent Water
Ash weight remains constant during weighing, and because the ash does
not melt it will not attack the crucible.
3.3 Test Method C, Ashing Cellulose by Schoniger
These test methods are under the jurisdiction of ASTM Committee D01 on
Oxidation—This test method is generally applicable to ashing
Paint and Related Coatings, Materials, and Applications and are the direct
celluloseforsubsequentanalysisofinorganicconstituents.The
responsibility of Subcommittee D01.36 on Cellulose and Cellulose Derivatives.
Current edition approved Dec. 1, 2019. Published December 2019. Originally procedure utilizes the Schoniger technique in which the cellu-
approved in 1976. Last previous edition approved in 2011 as D3516 – 89 (2011).
lose is burned in a combustion flask and all combustion
DOI: 10.1520/D3516-89R19E01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D3516 − 89 (2019)
products are dissolved in an aqueous medium, thus avoiding 6.3 Drying Oven, with the capability of maintaining a
the possibility of physical loss of sample such as can occur in temperature of 105 6 2°C.
dry ashing (Test Methods A and B). A limitation is the
6.4 Desiccator, such as silica gel, indicating drierite, or
relatively small sample of 1 g, which can be ashed without
magnesium perchlorate are suitable.
excessively large apparatus in which to carry out the oxidation
6.5 Muffle Furnace, electric, capable of maintaining a tem-
step. Small specimens may not be adequately representative
perature of 575 6 25°C, is recommended.
where a particulate contaminate is involved.
NOTE 3—Back to front temperatures in muffle furnaces frequently
3.4 Test Method D, Wet Ashing of Cellulose for Inorganics—
exceed the 625°C range, so that operating limits should be established for
This test method is recommended for ashing cellulose for
a given furnace.
subsequent analysis of inorganic constituents. The procedure
6.6 Dish, platinum, 100-mL capacity or larger. Porcelain
employs saturation of the cellulose with a concentrated solu-
crucibles are not recommended.
tion of hydrogen peroxide followed by incremental addition to
a small volume of concentrated sulfuric acid. It has the
6.7 Tongs, approximately 0.5 m (20 in.) long, with nickel-
advantage over Test Method C of not requiring special appa- chromium or platinum tips.
ratus and can be readily applied to samples of 5 to 10 g. The
7. Test Specimen
test method becomes tedious and less convenient for use where
larger specimens such as 50 or 100 g are required. Specimens
7.1 The amount of cellulose selected for each ash determi-
this large, although not generally required, may be necessary
nation depends on the ash content of the test specimen and
for the determination of trace levels of constituents such as
should be varied so that the weight of the ash will be not less
manganese or silica. Smaller samples may not be adequately
than10mgandpreferablyover20mg.Table1givessuggested
representative where a particulate contaminate is involved.
sample sizes.
7.2 Selection of the specimen shall be in such a manner as
4. Significance and Use
to be representative of the lot being tested.
4.1 Ash content gives an estimation of the inorganic content
NOTE 4—No set sampling procedure has been established to be
of cellulose samples. The presence of high levels of ash can be
applicable to all samples. It will suffice to specify that the specimen shall
expected to be detrimental to the process of making cellulose
be representative of the lot being sampled.
derivatives. It also provides a rough estimate of silica content
8. Procedure
whichcanhaveasignificanteffectontheperformanceoffilters
in cellulose derivative manufacturing facilities.
8.1 Weigh out, to the nearest 0.05 g, sufficient cellulose to
give the correct range of ash weight (see Table 1).At the same
5. Purity of Reagents
time, a separate specimen (3 to 5 g) should be weighed and
dried at 105°C for a moisture determination.
5.1 Reagent grade chemicals shall be used in all tests.
Unless otherwise indicated, it is intended that all reagents shall
NOTE 5—Test Methods D1348, Method B is suitable. However,
conform to the specifications of the Committee on Analytical
accuracy of the moisture test is not critical for the ash determination and
Reagents of the American Chemical Society, where such
any method capable of obtaining the percent oven dry within 0.5 % of the
true value is adequate.
specifications are available. Other grades may be used, pro-
vided it is first ascertained that the reagent is of sufficiently
8.2 Heat the platinum dish in the muffle furnace at 575°C
high purity to permit its use without lessening the accuracy of
for 15 min, cool and weigh to the nearest 0.1 mg. Place the
the determination.
weighed cellulose in the platinum dish and place the dish on
the open door of the muffle furnace, previously set and allowed
5.2 Purity of Water—Unless otherwise indicated, references
to reach equilibrium at 575°C. Allow the cellulose to char
to water shall be understood to mean reagent water as defined
without flame by gradually moving the dish into the muffle,
in Specification D1193.
and continue ashing with the door closed for 1 h.
TEST METHOD A—ASH IN CELLULOSE AT 575°C
NOTE 6—With some pulps, the character of the ash inhibits complete
carbon removal and gray or black specks persist after3hof ignition. The
6. Apparatus
addition of a few drops of distilled water to the ash after 8.3 followed by
drying and reignition at 575°C for1hor more may be required. Extreme
6.1 Balance, with an accuracy to 0.05 g is required for
cases may require a second treatment with water.
weighing cellulose samples.
NOTE 7—If the sample is too large, either separate ashings are required
6.2 Analytical Balance, with a sensitivity of 0.1 mg is
required. It should be checked with Class S weights.
TABLE 1 Suggested Sample Sizes
Ash, % Moisture-Free Cellulose, g
Over 0.5 5
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
0.20 to 0.5 10
Standard-Grade Reference Materials, American Chemical Society, Washington,
0.12 to 0.2 20
DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
0.08 to 0.12 30
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
0.04 to 0.08 40
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma- Less than 0.04 50
copeial Convention, Inc. (USPC), Rockville, MD.
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D3516 − 89 (2019)
or successive additions of cellulose are made with extreme care so as not
CaSO Na SO
4 2 4
5 1.36; 5 1.34 (3)
to disturb the ash. 8.2 is then repeated between each addition.
CaSO Na CO
3 2 2
8.3 Remove the dish from the muffle furnace and allow to
13.2 Selection of the specimen shall be in such a manner as
cool somewhat. Place it in the desiccator and allow it to cool to
to be representative of the lot being tested (see Note 4).
room temperature.
14. Procedure
NOTE 8—Care must be taken at all times to keep drafts away from the
light, fluffy ash.
14.1 Weigh out to the nearest 0.05 g sufficient cellulose to
8.4 Weigh the dish and ash to the nearest 0.1 mg. Reignite give the correct range of ash weight (see Table 1).At the same
for a 15-min period and reweigh. Repeat as required to obtain
time, weigh a separate specimen (3 to 5 g) and dry to constant
constant weight. weightat105 62°Cforamoisturedetermination(seeNote5).
14.2 See 8.2.
9. Calculation
14.3 Remove the dish and allow it to cool to room tempera-
9.1 Calculate the ash percent of moisture-free cellulose, E,
ture (see Note 7 and Note 8).
as follows:
14.4 Moisten the ash with 1 to 2 mLof concentrated H SO
2 4
C 2 B 100 100
~ !~ !~ !
E 5 (1)
and heat on a hot plate until all the dense white fumes of sulfur
A D
~!~ !
trioxide (SO ) are liberated.
where:
14.5 Place in the muffle furnace and ignite at 575°C for 1 h.
A = weight of specimen as is, g,
If carbon persists repeat 14.3, 14.4, and 14.5.
B = weight of dish, g,
14.6 After the last trace of carbon has disappeared, ignite in
C = weight of dish plus ash, g, and
the muffle furnace for1hat 575°C.
D = oven dry cellulose in specimen, %
14.7 Remove the dish and allow it to cool somewhat before
10. Report
placing it in desiccator and cooling to room temperature.
10.1 Report the results to the nearest 0.01 %. Duplicate
14.8 Weigh the dish and sulfated ash to the nearest 0.1 mg.
determinations should check within approximately 5 %.
Reignite for a 15-min period and reweigh. Repeat as required
to obtain constant weight.
11. Precision and Bias
NOTE 10—To remove the ash from the dish, clean with boiling
11.1 Aprecisionof8 %relativeatthe95 %confidencelevel
hydrochloric acid.
is found for specimens at the 0.05 % ash level.
NOTE 11—On igniting sulfated ash at 575°C, there should be no fusion
with the dishes, even when ashing cellulose that gives an alkaline ash.
11.2 No statement of bias can be made as no suitable
reference material exists for determining bias.
14.9 Prepare a reagent blank for the H SO corresponding
2 4
to the number of millilitres of H SO used in 14.4 and 14.5,by
2 4
TEST METHOD B—SULFATED ASH IN
the addition of the acid to a platinum dish after ignition and
CELLULOSE AT 575°C
true weight was determined, and carrying through 14.4 – 14.8
as they apply.
12. Apparatus and Reagent
12.1 Hot Plate.
15. Calculation
12.2 Additional apparatus shall be in accordance with Sec-
15.1 Calculate the sulfated ash, S, as percent of moisture-
tion 6.
free cellulose, as follows:
12.3 Sulfuric Acid—Concentrated H SO .
C 2 B 2 R 100 100
2 4 ~ !~ !~ !
S 5 (4)
~A!~D!
13. Test Specimen
where:
13.1 The amount of cellulose selected for each ash deter-
A = weight of specimen, g,
mination depends upon the sulfated ash content of the test
B = weight of dish, g,
specimen and should be varied so that the weight of the ash
C = weight of dish plus sulfated ash, g,
will be not less than 10 mg and preferably over 20 mg. Table
R = weight of H SO reagent blank residue, g, and
2 4
1 gives suggested specimen sizes for Test MethodA. The table
D = oven-dry cellulose in specimen, %.
is applicable to sulfated ash also, providing the percent ash
column is taken as percent sulfated ash.
16. Report
NOTE 9—The sulfated ash values will be higher than the ash obtained
16.1 Report the results to the nearest 0
...
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