ASTM D501-03(2023)

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.
Designation: D501 − 03 (Reapproved 2023)
Standard Test Methods of
Sampling and Chemical Analysis of Alkaline Detergents
This standard is issued under the fixed designation D501; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
Sections
Total Alkalinity as Sodium Oxide (Na O) 69 – 71
1.1 These test methods cover procedures for the sampling
Matter Insoluble in Water 72 and 73
and chemical analysis of inorganic alkaline detergents. Tetrasodium Pyrophosphate:
Sampling 74
1.2 The procedures appear in the following order:
Tetrasodium Pyrophosphate
(Na P O ) 75 – 79
4 2 7
Sections
Matter Insoluble in Water 80 and 81
Caustic Soda:
Loss on Ignition 82 and 83
Sampling 5
Borax:
Total Alkalinity as Sodium Oxide (Na O) 6 – 8
Sampling 84
Sodium Hydroxide (NaOH) 9 – 11
Total Borate and Excess Alkalinity or Acidity 85 – 87
Carbonate as Sodium Carbonate (Na CO ) 12
2 3
Matter Insoluble in Water 88 and 89
Carbon Dioxide (CO ) by the Evolution Method 13 – 16
Sodium Triphosphate:
Soda Ash:
Sampling 90
Sampling 17
Tritratable Na O 91 – 94
Matter Volatile at 150 °C to 155 °C 18 and 19
Total P O :
2 5
Total Alkalinity as Sodium Carbonate (Na CO ) 20 – 22
2 3
Preferred Method 95 – 97
Sodium Bicarbonate (NaHCO ) 23 – 25
Alternative Method 98 – 101
Sodium Bicarbonate (NaHCO ) by Potentiometric Titration 26 – 28
pH Titration 102 – 107
Matter Insoluble in Water 29 and 30
Quantitative Separation and Measurement of Various Phosphates:
Apparent Density 31 and 32
Reverse-Flow Ion-Exchange Chromatography (Preferred
Modified Soda (Sequicarbonate Type):
Method) 108 – 119
Sampling 33
Paper Chromatographic Method 120 – 127
Total Alkalinity as Sodium Oxide (Na O) 34 – 36
pH of 1 percent Solution 128
Sodium Bicarbonate (NaHCO ) and Sodium Carbonate (Na CO ) 37 – 39
3 2 3
Turbidity 129
Matter Insoluble in Water 40
Temperature Rise 130 – 134
Sodium Bicarbonate:
Sulfate 135 – 137
Sampling 41
Ignition Loss 140 and
Sodium Bicarbonate, Sodium Carbonate, and Free Moisture 42 – 45
Matter Insoluble in Water 46
Matter Insoluble in Water 142 – 144
Sodium Metasilicate, Sodium Sesquisilicate and Sodium Orthosil-
Particle Size 145
icate:
Orthophosphate 146 – 151
Sampling 47
Total Alkalinity as Sodium Oxide (Na O) 48 – 50
1.3 The values stated in SI units are to be regarded as
Total Silica as SiO 51 – 53
standard. No other units of measurement are included in this
Sodium Metasilicate (Na SiO ·5H O) 54
2 3 2
Sodium Sesquisilicate (3Na O·2SiO ·11H O) 55
2 2 2 standard.
Matter Insoluble in Water 56 and 57
Loss on Ignition of Sodium Sesquisilicate (3Na O·2SiO ·11H O) 58 and 59
2 2 2 1.4 This standard does not purport to address all of the
Sodium Orthosilicate (Na SiO ) 60
4 4
safety concerns, if any, associated with its use. It is the
Trisodium Phosphate:
Sampling 61 responsibility of the user of this standard to establish appro-
Trisodium Phosphate (Na PO ) Content and Phosphorus
3 4
priate safety, health, and environmental practices and deter-
Pentoxide (P O ) 62 – 64
2 5
mine the applicability of regulatory limitations prior to use.
Trisodium Phosphate Calculated as Na PO ·12H O, Na PO ·
3 4 2 3 4
H O, Na PO , and as P O 65 – 68
Material Safety Data Sheets are available for reagents and
2 3 4 2 5
materials. Review them for hazards prior to usage.
1.5 This international standard was developed in accor-
These test methods are under the jurisdiction of ASTM Committee D12 on
dance with internationally recognized principles on standard-
Soaps and Other Detergents and are the direct responsibility of Subcommittee
D12.12 on Analysis and Specifications of Soaps, Synthetics, Detergents and their
ization established in the Decision on Principles for the
Components.
Development of International Standards, Guides and Recom-
Current edition approved July 1, 2023. Published July 2023. Originally approved
mendations issued by the World Trade Organization Technical
in 1938. Last previous edition approved in 2016 as D501 – 03 (2016). DOI:
10.1520/D0501-03R23. Barriers to Trade (TBT) Committee.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D501 − 03 (2023)
2. Referenced Documents 4. Purity of Reagents
2.1 ASTM Standards:
4.1 Purity of Reagents—Reagent grade chemicals shall be
D459 Terminology Relating to Soaps and Other Detergents
used in all tests. Unless otherwise indicated, it is intended that
D1193 Specification for Reagent Water
all reagents shall conform to the specifications of the Commit-
E1 Specification for ASTM Liquid-in-Glass Thermometers
tee on Analytical Reagents of the American Chemical Society,
E70 Test Method for pH of Aqueous Solutions With the 3
where such specifications are available. Other grades may be
Glass Electrode
used, provided it is first ascertained that the reagent is of
3. Terminology sufficiently high purity to permit its use without lessening the
accuracy of the determination.
3.1 Definitions:
3.1.1 inorganic alkaline detergent—a water soluble inor-
4.2 Unless otherwise indicated, references to water shall be
ganic alkali or alkaline salt having detergent properties, but
understood to mean reagent water conforming to Specification
containing no soap or synthetics.
D1193.
3.1.2 For definitions of other terms used in these test
methods, refer to Terminology D459.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 The term “inorganic alkaline detergent” in these test
methods is defined in accordance with Terminology D459.
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Standard-Grade Reference Materials, American Chemical Society, Washington,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or DC. For suggestions on the testing of reagents not listed by the American Chemical
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
Standards volume information, refer to the standard’s Document Summary page on U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
the ASTM website. copeial Convention, Inc. (USPC), Rockville, MD.
CAUSTIC SODA
5. Sampling
5.1 Flake Caustic Soda—Flake caustic soda shall be the air as much as possible. Pipet a one-fifth aliquot into a
sampled by removing portions from various parts of the drum. 400 mL beaker and determine sodium oxide (Na O) by titrat-
ing the sample against 1.0 N acid, using methyl red as the
5.2 Powdered Caustic Soda—Powdered caustic soda shall
indicator.
be sampled by inserting a sampling tube through the contents
of the drum in several places. The tube shall be dried by
8. Calculation
heating just before use.
8.1 Calculate the total alkalinity as sodium oxide (Na O) as
5.3 Fused Caustic Soda—Fused caustic soda shall be
follows:
sampled by taking chipped samples from the center and bottom
Total alkalinity as Na O, % 5 ~A × 5 × 3.1!/W (1)
of the drum and then mixing the gross sample in the approxi- 2
mate proportions in which the tops and bottoms occur in the
where:
drum.
A = millilitres of acid required for titration of the Na O in
5.4 Precautions—Caustic soda shall not be sampled in a
the sample, and
moist atmosphere. In the case of fused caustic soda the portion W = grams of sample used.
taken for analysis shall have the surface layer of carbonate
SODIUM HYDROXIDE (NaOH)
scraped off immediately before transferring to the weighing
bottle. In all cases the sample shall be transferred to a
9. Reagents
thoroughly dried weighing bottle immediately after it is taken;
the bottle shall be tightly stoppered at once. 9.1 Acid, Standard (1.0 N)—Prepare and standardize a 1.0 N
acid solution.
TOTAL ALKALINITY AS SODIUM OXIDE (Na O)
9.2 Barium Chloride, Neutral Solution (100 g/L)—Dissolve
6. Reagents 100 g of barium chloride (BaCl ·2H O) in water and dilute to
2 2
1 L. Make the solution neutral to phenolphthalein.
6.1 Acid, Standard (1.0 N)—Prepare and standardize a 1.0 N
acid solution.
9.3 Phenolphthalein Indicator Solution (10 g/L)—Dissolve
1 g of phenolphthalein in 50 mL of ethyl alcohol and then mix
6.2 Methyl Red Indicator Solution.
with 50 mL of water.
7. Procedure
10. Procedure
7.1 Weigh 10 g of the sample, dissolve in carbon dioxide
(CO )-free water, wash into a 500 mL volumetric flask, and 10.1 Determine the NaOH on a second one-fifth aliquot
dilute to volume with CO -free water. Protect the solution from pipetted into a 250 mL Erlenmeyer flask. Add about 25 mL of
D501 − 03 (2023)
BaCl solution and titrate the sample with 1.0 N acid using Na CO , % 5 A 2 B × 5 × 5.3 /W (3)
@~ ! #
2 3
phenolphthalein as the indicator.
where:
11. Calculation
A = millilitres of acid required for titration of the Na O in
the sample,
11.1 Calculate the percentage of sodium hydroxide (NaOH)
B = millilitres of acid required for titration of the NaOH in
as follows:
the sample, and
NaOH, % 5 ~B × 5 × 4.0!/C (2)
W = grams of sample used.
where:
NOTE 1—When more accurate results are desired, the evolution method
for carbon dioxide as described in Sections 13 – 16 should be used.
B = millilitres of acid necessary for titration of the NaOH in
the sample, and
C = grams of sample used.
CARBONATE AS SODIUM CARBONATE (Na CO )
2 3
12. Calculation
12.1 Calculate the carbonate as sodium carbonate (Na CO )
2 3
as follows:
CARBON DIOXIDE (CO ) BY THE EVOLUTION METHOD
13. Apparatus
13.1 Apparatus Assembly—Place a 150 mL wide-neck ex- 15. Procedure
traction flask on a gauze over a burner. Fit the flask with a
15.1 Aspirate with a stream of carbon dioxide (CO )-free air
three-hole rubber stopper, one opening to carry a 25 cm reflux
at a rate of approximately 20 mL ⁄min to 30 mL ⁄min until the
condenser, the second to carry a thistle tube with a two-way
train is free from CO as determined by no further change in
stopcock for the introduction of acid into the flask, and the
weight greater than 0.3 mg in the U-tube.
third to carry a tube for the introduction of a continuous stream
15.2 Weigh 10 g of the sample to the nearest 0.01 g directly
of carbon dioxide (CO )-free air into the flask. Draw out the
into the extraction flask, cover with 50 mL of freshly boiled
ends of the thistle and air supply tubes to a small point, and
water, add 2 drops of methyl orange solution, and close the
place them in the stopper so that the points are very close to the
apparatus with the train in place. Start the aspiration at a rate of
bottom of the flask. Attach to the air supply tube, a U-tube
20 mL ⁄min to 30 mL ⁄min, and slowly add through the thistle
containing soda-asbestos (Ascarite) so that the air admitted to
tube sufficient H SO (2 + 9) to neutralize the NaOH and a
2 4
the flask will be free from CO .
sufficient excess to ensure the final acidity of the mixture as
indicated by the methyl orange. Always leave some acid in the
13.2 Preparation of Absorption Train—Attach to the top of
thistle tube as an air seal. Heat gently and continue until the
the reflux condenser a train consisting of the following:
contents of the flask have boiled for 5 min; remove the source
13.2.1 A U-tube containing granulated zinc for the removal
of heat, and continue aspirating until the flask has cooled, or for
of acid gases,
about 30 min.
13.2.2 A drying tube containing magnesium perchlorate,
15.3 Remove the U-tube containing soda-asbestos and
anhydrous calcium sulfate (Drierite), or anhydrous calcium
weigh using a tared U-tube as a counterpoise. The increase in
chloride,
weight represents CO .
13.2.3 A weighed U-tube containing soda-asbestos in the
16. Calculation
first half and the same drying agent in the second half as used
in 13.2.2, and
16.1 From the increase in weight of the tube calculate the
percentage of carbon dioxide (CO ) as sodium carbonate
13.2.4 A protective U-tube containing any of the above
mentioned drying agents. (Na CO ) as follows:
2 3
13.2.5 Attach the final tube to an aspirator.
Na CO , % 5 @~C × 2.409!/W# × 100 (4)
2 3
where:
14. Reagents
C = grams of CO , and
14.1 Methyl Orange Indicator Solution (1 g/L)—Dissolve
W = grams of sample used.
0.1 g of methyl orange in water and dilute to 100 mL. NOTE 2—This test method for the determination of Na CO as CO is
2 3 2
to be preferred when a procedure more accurate than that described in
14.2 Sulfuric Acid (2 + 9) —Mix 2 volumes of concentrated
Section 12 is required.
sulfuric acid (H SO , sp gr 1.84) carefully with stirring into 9
2 4
volumes of water.
D501 − 03 (2023)
SODA ASH
17. Sampling
17.1 Soda ash shall be sampled by removing portions from
W = grams of sample used.
various parts of the container. Samples shall not be taken from
SODIUM BICARBONATE (NaHCO )
those portions of the soda ash where caking is noticeable due
to the absorption of moisture and carbon dioxide through the
23. Reagents
container. If the soda ash is caked, the sample shall be obtained
23.1 Silver Nitrate Solution (100 g/L)—Dissolve 100 g of
by thoroughly mixing and quartering the entire contents of the
silver nitrate (AgNO ) in water and dilute to 1 L. Prepare this
package.
solution fresh before use.
MATTER VOLATILE AT 150 °C TO 155 °C
23.2 Sodium Hydroxide, Standard Solution (1.0 N)—
Prepare and standardize a 1.0 N sodium hydroxide (NaOH)
18. Procedure
solution.
18.1 Place approximately 2 g of the sample in a tared
24. Procedure
weighing bottle and weigh to the nearest 0.1 mg. Remove the
stopper and dry in an oven at 150 °C to 155 °C for 1 h. Replace
24.1 Weigh 8.4 g of the sample to the nearest 0.05 g and
the stopper and allow to cool to room temperature in a
transfer to a 250 mL beaker. Dissolve in 100 mL of water, and
desiccator containing no desiccant and reweigh.
titrate with 1.0 N NaOH solution until a drop of the test
solution added to a drop of AgNO solution on a spot plate
19. Calculation
gives a dark color instantly.
19.1 Calculate the percentage of volatile matter as follows:
25. Calculation
Volatile matter, % 5 L/W × 100 (5)
~ !
25.1 Calculate the percentage of sodium bicarbonate
where:
(NaHCO ) as follows:
L = grams loss in weight, and
NaHCO , % 5 mL of 1.0 N NaOH solution (7)
W = grams of sample used.
Calculate the percentage of sodium carbonate (Na CO ) as
2 3
TOTAL ALKALINITY AS SODIUM CARBONATE
follows:
(Na CO )
2 3
Na CO , % 5 A 2 NaHCO , % × 0.6309 (8)
~ !
2 3 3
20. Reagents
where:
20.1 Methyl Orange Indicator Solution (1 g/L)—Dissolve A = total alkalinity as Na CO , in percent.
2 3
NOTE 3—For referee purposes, or when more accurate results are
0.1 g of methyl orange in water and dilute to 100 mL.
required than are yielded by the procedure described in Section 25, the
20.2 Hydrochloric Acid, Standard (0.5 N)—Prepare and
method described in Section 28 shall be used.
standardize 0.5 N hydrochloric acid (HCl).
SODIUM BICARBONATE (NaHCO ) BY
POTENTIOMETRIC TITRATION
21. Procedure
21.1 Transfer approximately 1.2 g of sample into a tared
26. Reagents
weighing bottle. Weigh to the nearest 0.1 mg, protecting the
26.1 Barium Chloride, Neutral Solution (122 g/L)—
sample at all times, as much as possible, from moisture in the
Dissolve 122 g of barium chloride (BaCl ·2H O) in water and
2 2
air during weighing. Dissolve the sample in about 50 mL of
dilute to 1 L. Make the solution neutral to phenolphthalein.
water in a 400 mL beaker and add 2 drops of methyl orange
26.2 Hydrochloric Acid, Standard (0.1 N)—Prepare and
indicator solution. Run in, while stirring, 0.5 N HCl until 1
standardize 0.1 N hydrochloric acid (HCl).
drop establishes the first appearance of a pink color in the
solution. Remove the beaker, heat to boiling, and boil for 1min
26.3 Sodium Hydroxide, Standard Solution (0.1 N)—
to remove most of the CO . Cool and finish the titration to the
Prepare and standardize a 0.1 N sodium hydroxide (NaOH)
first appearance of a pink color in the solution.
solution.
22. Calculation 27. Procedure
22.1 Calculate the total alkalinity as sodium carbonate 27.1 Weigh approximately 10 g of the sample to the nearest
(Na CO ) as follows: 1 mg. Transfer to a 250 mL volumetric flask and dissolve in
2 3
freshly boiled, cooled water. Dilute to the mark, mix
Total alkalinity, % 5 ~AN × 5.3!/W (6)
thoroughly, and transfer, by means of a pipet, a 50 mL aliquot
where:
of the solution of a 250 mL beaker.
A = millilitres of HCl required for titration of the sample,
27.2 Add 5.0 mL of 0.1 N NaOH solution from a pipet or
N = normality of the HCl, and
buret; then add 50 mL of neutral BaCl solution. Introduce the
D501 − 03 (2023)
electrodes of a glass-electrode pH meter (Note 4) and mix
W = grams of sample in the aliquot.
continuously by means of a mechanical stirrer. Titrate with 0.1
MATTER INSOLUBLE IN WATER
N HCl without undue delay, in order to minimize absorption of
CO from the atmosphere. When the pH begins to change,
29. Procedure
record the readings at intervals of 0.1 mL of HCl.
29.1 Dissolve 20 g of the sample, weighed to the nearest
27.3 In an identical manner carry out a blank determination
0.1 g, in 300 mL of water in a 400 mL beaker. Filter through a
(Note 5) on 10 g of bicarbonate-free sodium carbonate
previously prepared, dried, and weighed Gooch or fritted-glass
(Na CO ) prepared by igniting another portion of the same
2 3
crucible. Wash the residue free of alkali with water and dry in
sample overnight at 200 °C.
an oven at 100 °C.
27.4 Plot the pH values versus millilitres of 0.1 N HCl for
30. Calculation
both the sample and the blank on the same paper. The volume
30.1 Calculate the percentage of matter insoluble in water as
of HCl represented by the difference between the points of
follows:
inflection of the two curves is equivalent to the sodium
bicarbonate content of the sample.
Matter insoluble in water, % 5 grams of residue × 5 (10)
NOTE 4—Careful standardization of the pH meter with standard buffers
APPARENT DENSITY
is not necessary. Instruments as specified in Test Method E70 are
satisfactory.
31. Procedure
NOTE 5—The blank correction is required since appreciable amounts of
31.1 Weigh 30 g of the sample and transfer to a 100 mL
NaOH are occluded in the precipitated BaCO . It is imperative that
identical quantities of NaOH be used for both sample and blank, since the
graduate. Rotate the graduate until the sample flows freely and
blank correction is related directly but not linearly to the quantity of
then, taking great care to avoid jarring, level the surface of the
excess NaOH present when the BaCO is precipitated. The correction
sample, and read the volume.
varies sufficiently with different reagents so that it should be measured for
each determination unless its constancy has been established.
32. Calculation
32.1 Calculate the apparent density as follows:
28. Calculation
28.1 Calculate the percentage of sodium bicarbonate A 5 30/V (11)
(NaHCO ) as follows:
Apparent density, lb/ft 5 A × 62.4
NaHCO , % @~A 2 B!N × 8.4#/W (9)
where:
where:
A = apparent specific gravity, and
A = millilitres of HCl required for titration of blank,
V = millilitres of sample.
B = millilitres of HCl required for titration of sample,
N = normality of the HCl, and
MODIFIED SODA (SESQUICARBONATE TYPE)
33. Sampling
33.1 The sample of modified soda (sesquicarbonate type) methyl red indicator solution and enough 1.0 N H SO to reach
2 4
shall be selected as described in Section 17 for the sampling of the end point plus approximately 1 mL in excess. Place a small
soda ash.
funnel in the neck of the flask and boil for 5 min to expel CO .
The solution should still be acid after boiling. Rinse down the
TOTAL ALKALINITY AS SODIUM OXIDE (Na O)
sides of the flask and back-titrate with 0.1 N NaOH solution.
34. Reagents
36. Calculation
34.1 Methyl Red Indicator Solution.
36.1 Calculate the total alkalinity as sodium oxide (Na O)
34.2 Sodium Hydroxide, Standard Solution (0.1 N)— 2
as follows:
Prepare and standardize a 0.1 N sodium hydroxide (NaOH)
solution.
Total alkalinity as Na O, percent 5 A 2 B/10 (12)
~ !
34.3 Sulfuric Acid (1.0 N)—Prepare and standardize 1.0 N
where:
sulfuric acid (H SO ).
2 4
A = millilitres of H SO required for titration of the sample,
2 4
and
35. Procedure
B = millilitres of NaOH solution required for titration of the
35.1 Weigh 3.1 g of the sample and dissolve in about
excess H SO .
2 4
100 mL of water in a 500 mL Erlenmeyer flask. Add 4 drops of
D501 − 03 (2023)
SODIUM BICARBONATE (NaHCO ) AND NaHCO , % 5 mL of 1.0 N NaOH solution (13)
SODIUM CARBONATE (Na CO )
2 3
39.2 Calculate the percentage of sodium carbonate
37. Reagents (Na CO ) as follows:
2 3
Na CO , % 5 X 2 Y × 0.3690 1.7097 (14)
37.1 Silver Nitrate Solution (100 g/L)—Dissolve 100 g of @ ~ !#
2 3
silver nitrate (AgNO ) in water and dilute to 1 L. Prepare the
where:
solution fresh before use.
X = percentage of sodium oxide (Na O) (Section 35), and
37.2 Sodium Hydroxide Solution (1.0 N)—Prepare and stan-
Y = percentage of NaHCO .
dardize a 1.0 N sodium hydroxide (NaOH) solution.
MATTER INSOLUBLE IN WATER
38. Procedure
38.1 Weigh 8.4 g of the sample and dissolve in about
40. Procedure
100 mL of water in a 250 mL beaker. Titrate the sample with
40.1 Determine the matter insoluble in water in accordance
1.0 N NaOH solution until a drop of the solution added to a
with the procedure described in Section 29.
drop of AgNO solution on a spot plate gives a dark color
instantly.
39. Calculation
39.1 Calculate the percentage of sodium bicarbonate
(NaHCO ) as follows:
SODIUM BICARBONATE
41. Sampling
41.1 Unless caking is noticeable, sodium bicarbonate shall outside diameter and the remaining 15 cm is 10 mm in outside
be sampled by removing portions from various parts of the diameter, and having a side arm 10 mm in outside diameter
container. If the sodium bicarbonate is caked, the sample shall attached at a point 5 cm from the large end of the tube.
be obtained by thoroughly mixing and quartering the entire
43.1.4 Air-Pretreatment Tube, approximately 30 mm in
contents of the package. diameter and 30 cm in length, packed as follows, the various
materials, in approximately equal proportions, being separated
SODIUM BICARBONATE (NaHCO ), SODIUM
by glass-wool plugs: “indicating” anhydrous calcium sulfate
CARBONATE (Na CO ), AND FREE MOISTURE 4
2 3
(Drierite) at the entry end, followed by anhydrous magnesium
perchlorate (Dehydrite or Anhydrone), soda-asbestos
42. Summary of Test Method
(Ascarite), and anhydrous magnesium perchlorate again.
42.1 Sodium bicarbonate is thermally decomposed in a
43.1.5 Moisture-Absorption Tube, consisting of a U-tube
special apparatus, and the carbon dioxide evolved is absorbed
with ground-glass stopcocks, the over-all height being approxi-
and weighed. The reaction is as follows:
mately 15 cm and the bore 13 cm, packed with “indicating”
2 NaHCO →Na CO 1H O1CO (15)
anhydrous calcium sulfate and anhydrous magnesium perchlo-
3 2 3 2 2
rate.
The loss in weight of the sample is determined, and the
43.1.6 Carbon Dioxide Absorption Tube—A standard Nes-
content of NaHCO and free water are calculated from these
bitt bulb, approximately 13.5 cm in height, packed with
values. The Na CO content is estimated by difference, the
2 3
sodaasbestos, with a relatively thin layer of anhydrous magne-
result representing the sum of the Na CO content and the
2 3
sium perchlorate at the exit end.
minor nonvolatile impurities.
43.1.7 Sample Boat, platinum, with a close-fitting cover,
43. Apparatus
approximately 9.5 cm in over-all length, 12 mm wide, and
9 mm high.
43.1 The apparatus shall be assembled as shown in Fig. 1
43.1.8 Bubbler Tube, having an orifice 5 mm in inside
and shall consist of the following:
diameter, and containing concentrated sulfuric acid (H SO , sp
2 4
43.1.1 Electric Furnace, split-type, approximately 33 cm in
gr 1.84).
length, with an opening 3.5 cm in diameter, and with a power
43.1.9 Connections—Chemically resistant plastic tubing
requirement of approximately 750 W.
(Tygon or equivalent) connections of suitable internal
43.1.2 Variable Transformer, having an adequate capacity to
diameter, predried in a vacuum desiccator for 24 h followed by
supply the full rated power of the furnace, and capable of
heating at 110 °C for 30 min prior to use, and with the inner
reducing the input voltage so that the temperature of the
furnace can be maintained continuously at any value between
95 °C and 275 °C.
43.1.3 Decomposition Tube, of heat-resistant glass, having
The commercially available grade that shows a distinct color change with use
an over-all length of 53 cm, of which 38 cm is 30 mm in is preferred for this purpose.
D501 − 03 (2023)
surface coated very lightly with silicone stopcock grease or a 44.3.4 Discontinue heating, and continue sweeping for at
thin film of castor oil. least 30 min.
43.1.10 Cooling Chamber, consisting of an aluminum disk The total time covered by 44.3.1 – 44.3.4 should be between
approximately 15 cm in diameter and 3 cm in thickness, and a 2 ⁄2 h and 3 h.
petri dish with the lip ground to fit the disk, as a cover.
NOTE 6—The rate of sweeping and the heating procedure are such that
43.1.11 Thermometer—An ASTM Partial Immersion
back-diffusion of the products of decomposition is prevented. At 120 °C,
Thermometer, having a range from − 5 °C to + 300 °C, and
approximately 12 mL of gaseous decomposition products per min are
released from a 2.5 g sample of sodium bicarbonate. The specified flow
conforming to the requirements for Thermometer 2C as pre-
rate (50 mL/min) is in excess of four times this amount, providing an air
scribed in Specification E1.
FIG. 1 Apparatus Assembly for Determination of Carbon Dioxide
velocity of approximately 10 cm/min. Too rapid heating, or inadequate
44. Procedure
sweeping, may be evidenced by condensation of moisture at the entry end
44.1 Sweep the assembled apparatus at room temperature, of the decomposition tube. In this case the determination should be
discarded, since absorption of carbon dioxide (CO ) from the sample in
without sample, by drawing air through it for 15 min at a fairly 2
the air-pretreatment tube can occur. To prevent this occurrence, the
rapid rate. Remove the Nesbitt bulb. Wipe it, and an identical
recommended heating schedule and sweeping rate should be observed.
bulb to be used as a counter-weight, with a moist chamois skin
The bubbler tube may be roughly calibrated by the use of a wet-test meter,
or lintless cloth, allow both bulbs to stand in the balance case as an aid in establishing adequate sweeping rates.
for 15 min, and then weigh. In order to check the apparatus for
44.4 Close the stopcocks, on the Nesbitt bulb and on the
leaks, the sweeping and weighing may be repeated. The change
U-tube. Open the furnace, place the cover on the boat, and
in weight in the bulb should be less than 0.1 mg.
remove the boat, placing it immediately in the aluminum block
cooling chamber. Allow to cool 2 min, and then quickly weigh.
44.2 Weigh 2 g to 3 g of the sample of sodium bicarbonate
Remove the Nesbitt bulb from the assembly, and carefully
to the nearest 0.1 mg into the platinum combustion boat, using
wipe it free of any silicone grease that may adhere to the tube.
the cover. Quickly insert the boat into the decomposition tube
Open the stopcock momentarily to the atmosphere to equalize
at room temperature, removing the cover and allowing it to
pressure, and wipe both the bulb and the tare with a moist
remain in the tube. Close the tube by inserting the stopper
chamois skin or lintless cloth. Allow to stand in the balance
bearing the thermometer. The boat should be located approxi-
case for 15 min, and then weigh to the nearest 0.1 mg.
mately two thirds of the length of the tube from the inlet end,
and the thermometer should extend nearly the same distance.
45. Calculation
Open the stopcocks in the U-tube and in the Nesbitt bulb, and
45.1 Calculate the percentages of sodium bicarbonate
adjust the air flow so that a moderately rapid stream of bubbles
(NaHCO ), free water, and sodium carbonate (Na CO ) as
3 2 3
passes through the H SO bubbler. The minimum rate of flow
2 4
follows:
should be 50 mL of air per min.
A 5 3.818D/E × 100 (16)
~ !
44.3 Turn on the electric furnace, and control the tempera-
ture by means of the variable transformer in accordance with
B 5 @~F 2 1.409D!/E# × 100
the following schedule:
C 5 100 2 A1B
~ !
44.3.1 Increase the temperature from room temperature to
95 °C as rapidly as desired. where:
44.3.2 After reaching 95 °C, adjust the transformer so that A = percentage of NaHCO ,
B = percentage of free water,
the temperature does not exceed 120 °C at the end of 1 h.
C = percentage of Na CO ,
2 3
44.3.3 During the second hour of sweeping, gradually
D = grams of CO (Section 44),
increase the temperature to 275 °C.
D501 − 03 (2023)
E = grams of sample used for CO determination, and
F = ignition loss, in grams (original weight of boat and
sample minus weight of boat and residue after ignition
(see 44.2 and 44.3).
NOTE 7—The Na CO values reported represent the sum of the Na CO
2 3 2 3
and the other nonvolatile impurities that may be present.
MATTER INSOLUBLE IN WATER
46. Procedure
46.1 Determine the matter insoluble in water in accordance
with the procedure described in Section 29.
SODIUM METASILICATE, SODIUM SESQUISILICATE AND SODIUM ORTHOSILICATE
47. Sampling
47.1 Sodium metasilicate, sodium sesquisilicate and sodium 51.2 Hydrochloric Acid (1 + 1) —Mix 1 volume of HCl (sp
orthosilicate shall be sampled by removing portions from gr 1.19) with 1 volume of water.
various parts of the container. Samples shall not be taken from
51.3 Hydrofluoric Acid (sp gr 1.15)—Prepare a solution of
those portions of the material where caking is noticeable due to
hydrofluoric acid (HF) having a specific gravity of 1.15.
the absorption of moisture and carbon dioxide through the
51.4 Sulfuric Acid (1 + 1) —Add 1 volume of concentrated
container. If the material is caked, the sample shall be obtained
sulfuric acid (H SO , sp gr 1.84) carefully with stirring to 1
2 4
by thoroughly mixing and quartering the entire contents of the
volume of water.
package.
TOTAL ALKALINITY AS SODIUM OXIDE (Na O)
52. Procedure
52.1 Transfer the titrated solution as obtained under Section
48. Reagents
49 to a porcelain evaporating dish, add 25 mL of HCl (sp gr
48.1 Hydrochloric Acid, Standard (0.5 N)—Prepare and
1.19), and evaporate to apparent dryness on a steam bath.
standardize 0.5 N hydrochloric acid (HCl).
Triturate the dehydrated residue with the smooth end of a
48.2 Methyl Orange Indicator Solution (1 g/L)—Dissolve stirring rod, moisten the residue with 10 mL of HCl (1 + 1),
and again evaporate to apparent dryness on the steam bath.
0.1 g of methyl orange in water and dilute to 100 mL.
Dehydrate at 110 °C for 1 h, take up the residue with 10 mL of
49. Procedure
HCl (1 + 1) and 20 mL of water, and digest a short time on the
steam bath to effect solution of the soluble salts. Filter the silica
49.1 Weigh 20 g of the sample to the nearest 1 mg in a
on a fine-texture paper by washing the dish with hot water.
stoppered weighing bottle. Transfer directly to a 500 mL
Scrub the dish with a rubber policeman and again wash
volumetric flask, dissolve in water, dilute to exactly 500 mL,
thoroughly with hot water. Wash the residue and paper free of
and mix thoroughly. Transfer a 50 mL aliquot to a 250 mL
acid with hot water and reserve.
beaker. Titrate with 0.5 N HCl, using methyl orange as the
indicator to the first permanent color change. Reserve the
52.2 Evaporate the filtrate and washings on the steam bath
titrated solution for the determination of total silica as de-
in the porcelain dish used before, moisten the residue with
scribed in Section 52.
10 mL of HCl (1 + 1), and again evaporate to dryness. Dehy-
drate at 110 °C for 1 h, take up the residue with 10 mL of HCl
50. Calculation
(1 + 1) and 20 mL of water, digest as before to dissolve soluble
50.1 Calculate the total alkalinity as sodium oxide (Na O) salts, and filter off any additional silica on a separate filter
as follows: paper. Scrub the dish and wash the residue and filter paper free
from acid as before.
Total alkalinity as Na O, % 5 V × N × 3.1 /W (17)
~ !
52.3 Transfer both papers and residues to a platinum cru-
where:
cible previously ignited and weighed without cover, and ignite
V = millilitres of HCl required for titration of the sample,
in a muffle furnace until free from carbon, heating slowly at
N = normality of the HCl, and
first. Cover the crucible with a platinum cover, heat to the
W = grams of sample in the aliquot.
highest temperature of a blast lamp for 15 mm, cool in a
desiccator, and weigh without the crucible cover.
TOTAL SILICA AS SILICA (SiO )
52.4 Add 5 mL of water to the contents of the crucible and
51. Reagents
2 or 3 drops of H SO (1 + 1), then slowly introduce approxi-
2 4
51.1 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro- mately 10 mL of HF. Evaporate to a small volume on the steam
chloric acid (HCl). bath, add another portion of about 10 mL of HF, and evaporate
D501 − 03 (2023)
to fumes of H SO . Heat the crucible, gently at first, over an temperature and dilute to approximately 900 mL. Filter by
2 4
open flame to drive off H SO , and finally at a bright red heat. suction through a prepared, dried, and weighed Gooch
2 4
Cool in a desiccator, and weigh. The loss in weight represents
crucible, using on the crucible a pad made of asbestos fiber
SiO .
only. Wash the beaker and residue free from alkali with water,
and dry the crucible to constant weight in an oven at 110 °C.
53. Calculation
Cool in a desiccator, and weigh.
53.1 Calculate the percentage of silica (SiO ) as follows:
SiO , % 5 @~A 2 B!/W# × 100 (18) 57. Calculation
where:
57.1 Calculate the percentage of matter insoluble in water
A = grams of ignited residue before treatment with HF 52.3, from the average gain in weight of two checking duplicate
B = grams of ignited residue after treatment with HF 52.4,
determinations as follows:
and
Matter insoluble in water, % 5 grams of residue (23)
W = grams of sample in aliquot.
LOSS ON IGNITION OF SODIUM SESQUISILICATE
SODIUM METASILICATE (Na SiO ·5H O)
2 3 2
(3Na O·2SiO ·11H O)
2 2 2
54. Calculation
58. Procedure
54.1 If the ratio of the percentage of silica (SiO ) divided by
the percentage total alkalinity as sodium oxide (Na O) is less
58.1 Weigh about 2 g of sand in a clean platinum crucible
than 0.969, calculate the percentage of sodium metasilicate as
with a tight-fitting lid, and ignite to constant weight. Weigh
follows:
about 2 g of the sodium sesquisilicate in the crucible, and heat
Na SiO ·5H O, % 5 total SiO , % × 3.53 (19)
with a low flame until the silicate is melted. Increase the heat
2 3 2 2
gradually as the water is driven off, care being taken to prevent
54.2 If this ratio is greater than 0.969, calculate the percent-
spattering. Ignite to constant weight. Cool in a desiccator, and
age of sodium metasilicate as follows:
weigh.
Na SiO ·5H O, % 5 total alkalinity as Na O, % × 3.42 (20)
2 3 2 2
SODIUM SESQUISILICATE (3Na O·2SiO ·11H O) 59. Calculation
2 2 2
55. Calculation 59.1 Calculate the loss on ignition as follows:
55.1 If the ratio of the percentage of silica (SiO ) divided by Loss on ignition, % 5 L/W × 100 (24)
~ !
the percentage total alkalinity as sodium oxide (Na O) is less
where:
than 0.646, calculate the percentage of sodium sesquisilicate as
L = grams loss in weight, and
follows:
W = grams of sample used.
3Na O·2SiO ·11H O, % 5 total SiO , % × 4.20 (21)
2 2 2 2
SODIUM ORTHOSILICATE (Na SiO )
55.2 If the ratio is greater than 0.646, calculate the per- 4 4
centage of sodium sesquisilicate as follows:
60. Results
3Na O·2SiO ·11H O, % 5 total Na O, % × 2.71 (22)
2 2 2 2
60.1 Express the results of analysis of sodium orthosilicate
MATTER INSOLUBLE IN WATER
in terms of sodium oxide (Na O), silica (SiO ), and matter
2 2
insoluble in water.
56. Procedure
56.1 Weigh 100 g of the sample to the nearest 0.5 g and
transfer to a 1 L beaker. Dissolve by stirring with water at room
TRISODIUM PHOSPHATE
61. Sampling
61.1 Trisodium phosphate, hydrated or anhydrous, shall be phosphate is caked, the sample shall be obtained by thoroughly
sampled by removing portions from various parts of the
mixing and quartering the entire contents of the package.
container. Samples shall not be taken from those portions
where caking is noticeable due to the absorption of moisture
and carbon dioxide through the container. If the trisodium
D501 − 03 (2023)
TRISODIUM PHOSPHATE (Na PO ) CONTENT AND preferably in a muffle furnace, until the paper chars without
3 4
PHOSPHORUS PENTOXIDE (P O ) inflaming. Burn off the carbon at the lowest possible tempera-
2 5
ture and then ignite to constant weight at 950 °C to 1000 °C.
62. Reagents
Cool in a desiccator, and weigh as magnesium pyrophosphate
(Mg P O ).
62.1 Ammonium Chloride (NH Cl).
2 2 7
62.2 Ammonium Hydroxide (1 + 1) —Mix 1 volume of
64. Calculation
concentrated ammonium hydroxide (NH OH, sp gr 0.90) with
64.1 Calculate the percentage of trisodium phosphate as
1 volume of water.
follows:
62.3 Ammonium Hydroxide (1 + 20) —Mix 1 volume of
Na PO ·12H O, % 5 ~grams of Mg P O × 3415.61!/W (25)
3 4 2 2 2 7
NH OH (sp gr 0.90) with 20 volumes of water.
62.4 Hydrochloric Acid (1 + 1) —Mix 1 volume of concen-
Na PO ·H O, % 5 ~grams of Mg P O × 1634.97!/W
3 4 2 2 2 7
trated hydrochloric acid (HCl, sp gr 1.19) with 1 volume of
Na PO , % 5 grams of Mg P O × 1473.09 /W
~ !
water. 3 4 2 2 7
62.5 Hydrochloric Acid (1 + 20) —Mix 1 volume of HCl (sp
P O , % 5 grams of Mg P O × 637.72 /W
~ !
2 5 2 2 7
gr 1.19) with 20 volumes of water.
where W in all cases is the grams of the original sample used.
62.6 Magnesia Mixture Reagent—Dissolve 50 g of magne-
sium chloride, (MgCl ·6H O) and 100 g of NH Cl in 500 mL
TRISODIUM PHOSPHATE CALCULATED AS
2 2 4
of water. Add NH OH in slight excess, allow to stand over Na PO ·12H O,
4 3 4 2
night, and filter. Make just acid with HCl, dilute to 1 L, and Na PO ·H O, Na PO , AND AS P O
3 4 2 3 4 2 5
keep in a glass-stoppered bottle. (Alternative Method)
62.7 Methyl Red Indicator Solution.
65. Apparatus
63. Procedure
65.1 Filter, by means of suction through a ⁄4 in. paper-pulp
filter pad, supported on a 1 in. perforated porcelain plate, into
63.1 Weigh 5 g of trisodium phosphate dodecahydrate
a 500 mL suction flask.
(Na PO ·12H O), 2.4 g of the monohydrate (Na PO ·H O), or
3 4 2 3 4 2
2.2 g of the anhydrous sample (Na PO ) in a weighing bottle,
65.2 Filter Aid—A suspension of purified diatomaceous
3 4
transfer directly to a 500 mL volumetric flask, dissolve in
earth.
water, dilute to exactly 500 mL, and mix thoroughly. If any
66. Reagents
turbidity exists, filter through a dry paper into a dry beaker,
discard the first 100 mL of filtrate, and then transfer a 50 mL
66.1 Ammonium Hydroxide (sp gr 0.90)—Concentrated am-
aliquot to a 400 mL beaker. Add 5 g of NH Cl, 40 mL of water,
4 monium hydroxide (NH OH).
a drop or two of methyl red indicator solution, and make
66.2 Ammonium Molybdate Solution—Dissolve 118 g of
slightly acid with HCl, cool, and add 25 mL of magnesia
molybdic acid (85 % MoO ) in a mixture of 400 mL of water
mixture. Slowly add NH OH (1 + 1), while stirring constantly.
and 80 mL of NH OH (sp gr 0.90). Cool, filter if necessary, and
When the white crystalline precipitate of magnesium phos-
pour, while stirring, into a cool mixture of 400 mL of
phate begins to appear, stop the addition of NH OH, stir until
concentrated nitric acid (HNO , sp gr 1.42) and 600 mL of
no further precipitate appears, and then add NH OH (1 + 1) a
water. Add about 0.05 g of disodium hydrogen phosphate
few drops at a time, while stirring constantly, until the solution
(Na HPO ) dissolved in a little water. Mix and let settle over
2 4
is alkaline. Add 15 mL of NH OH (1 + 1) in excess and set the
24 h. Use the clear, supernatant liquor, filtering if necessary.
solution aside for 4 h in an ice bath or preferably over night at
Store in a cool, dark place.
room temperature.
66.3 Methyl Orange Indicator Solution (1 g/L)—Dissolve
63.2 Filter without attempting to transfer the precipitate,
0.1 g of methyl orange in water and dilute to 100 mL.
and wash the vessel, residues, and paper a few times with
NH OH (1 + 20). Dissolve the precipitate in 25 mL of HCl 66.4 Nitric Acid (sp gr 1.42)—Concentrated nitric acid
(HNO ).
(1 + 1) catching the solution in the original beaker containing
the bulk of the precipitate, and wash the filter thoroughly with
66.5 Nitric Acid (1 + 15) —Mix 1 volume of concentrated
HCl (1 + 20). Dilute the solution to 100 mL and add 2 mL of
nitric acid (HNO , sp gr 1.42) with 15 volumes of water.
the magnesia mixture reagent. Precipitate the magnesium
66.6 Nitric Acid, Standard (0.324 N)—Prepare 0.324 N
phosphate with NH OH (1 + 1), while stirring constantly, as
HNO , using carbon dioxide (CO )-free water. Standardize
3 2
described in 63.1, and finally add 10 mL of NH OH (1 + 1) in
against the 0.324 N NaOH solution (66.9).
excess. Allow the solution to stand at least 2 h in an ice bath or
preferably over night at room temperature. 66.7 Phenolphthalein Indicator Solution (10 g/L)—Dissolve
1 g of phenolphthalein in 50 mL of ethyl alcohol and then mix
63.3 Filter on an ashless filter paper, transfer the precipitate
with 50 mL of water.
to the filter, and wash with NH OH (1 + 20) until free from
chlorides. Transfer the precipitate and filter paper to an ignited, 66.8 Potassium Nitrate Solution (10 g KNO /L)—Dissolve
tared platinum or porcelain crucible; dry, and heat carefully, 10 g of potassium nitrate (KNO ) in water and dilute to 1 liter.
D501 − 03 (2023)
66.9 Sodium Hydroxide, Standard Solution (0.324 N)—
B = millilitres of 0.324 N HNO required for titration of the
Prepare a 0.324 N solution of sodium hydroxide (NaOH), using
excess NaOH,
carbon dioxide (CO )-free water. Standardize against the
F = equivalent value of 0.324 N solution in terms of P O
2 5
National Institute of Standards and Technology standard
as calculated (0.001) or that obtained by actual stan-
sample No. 39 of benzoic acid. One millilitre of 0.324 N NaOH
dardizing against KH PO , and
2 4
solution equals 0.001 g of P O in the titration of ammonium W = grams of sample used.
2 5
phosphomolybdate.
68.2 Calculate the equivalent percentages of trisodium
phosphate dodecahydrate, monohydrate, and anhydrous form,
NOTE 8—For work of average precision, the percentage of total P O
2 5
can be calculated on the basis that 1 mL of the net standard alkali is
as follows:
equivalent to 0.001 g of P O . Use of this factor has been found to give
2 5
Na PO ·12H O, % 5 total P O , % × 5.356 (27)
results correct to within about 1 % of the absolute value. In order to obtain 3 4 2 2 5
a higher degree of accuracy, it is advisable to standardize the base against
Na PO ·H O, % 5 total P O , % × 2.564
a standard sample with an exactly known phosphorus content and having
3 4 2 2 5
a composition very similar to that of the unknown being analyzed. It has
proved very satisfactory in the case of the analysis of commercial Na PO , % 5 P O , % × 2.310
3 4 2 5
phosphate salts to standardize the NaOH with pure potassium dihydrogen
phosphate (KH PO ), using an amount of the standard KH PO to give a TOTAL ALKALINITY AS SODIUM OXIDE (Na O)
2 4 2 4 2
volume of phosphomolybdate precipitate nearly equal to that of the
unknown. Recrystallized sodium pyrophosphate (Na P O ) may also be
4 2 7
69. Reagents
used as a standard. It should be noted that the KH PO sample should
2 4
contain about the same amount of sulfate and chloride ion as the unknown. 69.1 Hydrochloric Acid, Standard (1.0 N)—Prepare and
standardize 1.0 N hydrochloric acid (HCl).
67. Procedure
69.2 Methyl Orange Indicator Solution (1 g/L)—See 66
...