ASTM D94-07(2012)e1
(Test Method)Standard Test Methods for Saponification Number of Petroleum Products
Standard Test Methods for Saponification Number of Petroleum Products
SIGNIFICANCE AND USE
5.1 Petroleum products can contain additives that react with alkali to form metal soaps. Fats are examples of such additives. Also, certain used engine oils, especially from turbine or internal combustion engines, can contain chemicals that will similarly react with alkali. The saponification number expresses the amount of base that will react with 1 g of sample when heated in a specific manner. This then gives an estimation of the amount of acid present in the sample, that is, any free acid originally present plus any combined (for example, in esters) that have been converted to metal soaps during the heating procedure.
5.2 Saponification numbers are also used in setting product specifications for lubricants and additives.
SCOPE
1.1 These test methods cover the determination of the amount of constituents in petroleum products such as lubricants, additives, and transmission fluids that will saponify under the conditions of the test.
Note 1: Statements defining this test and its significance when applied to electrical insulating oils of mineral origin will be found in Guide D117. Experience has shown that for transformer oils, Test Method D94, modified by use of 0.1 M KOH solution and 0.1 M HCl, is more suitable.
1.1.1 Two test methods are described: Method A—Color Indicator Titration (Sections 6 – 13), and Method B—Potentiometric Titration (Sections 14 – 23).
1.2 Because compounds of sulfur, phosphorus, the halogens, and certain other elements that are sometimes added to petroleum products also consume alkali and acids, the results obtained indicate the effect of these extraneous materials in addition to the saponifiable material present. Results on products containing such materials, on used internal-combustion-engine crankcase oils, and on used turbine oils must be interpreted with caution.
Note 2: The materials referred to above, which are not normally considered saponifiable matter, include inorganic or certain organic acids, most nonalkali soaps, and so forth. The presence of such materials increases the saponification number above that of fatty saponifiable materials for which the test method is primarily intended. The odor of hydrogen sulfide near the end of the back-titration in the saponification test is an indication that certain types of reactive sulfur compounds are present in the sample. In the case of other reactive sulfur, chlorine, and phosphorus compounds and other interfering materials, no simple indication is given during the test. A gravimetric determination of the actual amount of fatty acids is probably the most reliable method for such compounds. Test Methods D128 or IP Method 284/86 can be used to determine fatty acids gravimetrically.
1.3 The values stated in SI units are to be regarded as the standard.
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 Sections 6, 7, 8, 10, 15, 16, 17, and 19.
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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: D94 −07 (Reapproved 2012)
Designation: 136S1/98, 136S2/99
Standard Test Methods for
Saponification Number of Petroleum Products
ThisstandardisissuedunderthefixeddesignationD94;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
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.
ε NOTE—The Research Report number in 23.1 was corrected editorially in May 2015.
1. Scope 1.3 The values stated in SI units are to be regarded as the
standard.
1.1 These test methods cover the determination of the
1.4 This standard does not purport to address all of the
amount of constituents in petroleum products such as
safety concerns, if any, associated with its use. It is the
lubricants, additives, and transmission fluids that will saponify
responsibility of the user of this standard to establish appro-
under the conditions of the test.
priate safety and health practices and determine the applica-
NOTE1—Statementsdefiningthistestanditssignificancewhenapplied
bility of regulatory limitations prior to use.For specific hazard
toelectricalinsulatingoilsofmineraloriginwillbefoundinGuideD117.
statements, see Sections 6, 7, 8, 10, 15, 16, 17, and 19.
Experience has shown that for transformer oils, Test Method D94,
modified by use of 0.1 M KOH solution and 0.1 M HCl, is more suitable.
2. Referenced Documents
1.1.1 Two test methods are described: Method A—Color
2.1 ASTM Standards:
Indicator Titration (Sections 6–13), and Method
B—Potentiometric Titration (Sections14–23). D117Guide for Sampling,Test Methods, and Specifications
for Electrical Insulating Oils of Petroleum Origin
1.2 Because compounds of sulfur, phosphorus, the
D128Test Methods for Analysis of Lubricating Grease
halogens, and certain other elements that are sometimes added
D1193Specification for Reagent Water
to petroleum products also consume alkali and acids, the
D4057Practice for Manual Sampling of Petroleum and
results obtained indicate the effect of these extraneous materi-
Petroleum Products
als in addition to the saponifiable material present. Results on
D4177Practice for Automatic Sampling of Petroleum and
products containing such materials, on used internal-
Petroleum Products
combustion-engine crankcase oils, and on used turbine oils
D6299Practice for Applying Statistical Quality Assurance
must be interpreted with caution.
and Control Charting Techniques to Evaluate Analytical
NOTE 2—The materials referred to above, which are not normally
Measurement System Performance
considered saponifiable matter, include inorganic or certain organic acids,
D6792Practice for Quality System in Petroleum Products
most nonalkali soaps, and so forth. The presence of such materials
and Lubricants Testing Laboratories
increases the saponification number above that of fatty saponifiable
materials for which the test method is primarily intended. The odor of 2.2 Energy Institute Standards:
hydrogen sulfide near the end of the back-titration in the saponification
IP 136Method of Test for Saponification Number of Petro-
test is an indication that certain types of reactive sulfur compounds are
leum Products
present in the sample. In the case of other reactive sulfur, chlorine, and
IP 284Method of Test for Fatty Acids
phosphorus compounds and other interfering materials, no simple indica-
tion is given during the test. A gravimetric determination of the actual
amount of fatty acids is probably the most reliable method for such 3. Terminology
compounds. Test Methods D128 or IP Method284/86 can be used to
3.1 Definitions:
determine fatty acids gravimetrically.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
These test methods are under the jurisdiction of ASTM Committee D02 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Petroleum Products, Liquid Fuels, and Lubricants and are the direct responsibility Standards volume information, refer to the standard’s Document Summary page on
of Subcommittee D02.06 on Analysis of Liquid Fuels and Lubricants. the ASTM website.
Current edition approved Nov. 1, 2012. Published November 2012. Originally Available from Institute of Petroleum, 61 New Cavendish St., London, W.I.,
approved in 1921. Last previous edition approved in 2007 as D94–07. DOI: England.Available from Energy Institute, 61 New Cavendish St., London, WIG
10.1520/D0094-07R12E01. 7AR, U.K., http://www.energyinst.org.uk.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
D94 − 07 (2012)
3.1.1 saponification number, n—the number of milligrams all reagents shall conform to the specifications of the Commit-
ofpotassiumhydroxideconsumedby1gofasampleunderthe tee onAnalytical Reagents of theAmerican Chemical Society,
conditions of the test. where such specifications are available. Other grades may be
3.1.1.1 Discussion—Thevalueofthesaponificationnumber used, provided it is first ascertained that the reagent is of
in these test methods can be affected by the presence of other sufficiently high purity to permit its use without lessening the
alkali-reactive species, as described in Note 2. accuracy of the determination.
3.1.2 saponify, v—to hydrolyze a fat with alkali to form an
NOTE 4—Commercially available reagents may be used in place of
alcohol and the salt of a fatty acid. laboratory preparations, provided they meet the specifications outlined.
7.2 Purity of Water—Unless otherwise indicated, references
4. Summary of Test Method
to water shall be understood to mean reagent water as defined
4.1 A known mass of the sample is dissolved in a suitable
by Type I, II, or III in Specification D1193.
solvent, such as butanone (methylethylketone), xylenes, or
7.3 Alcohol —95 % ethanol (Warning—Flammable.
Stoddard Solvent, or a combination thereof (Warning—
Denatured—Cannot be made nontoxic) (see Note 5) and
Extremely flammable. Vapors can cause flash fire), and is
(Warning—Flammable) or 95% ethanol to which has been
heatedwithaknownamountofalcoholicpotassiumhydroxide
added 10 volume % of methanol (see Note 5 and Note 6)or
(KOH).Theexcessalkaliistitratedwithstandardacid,andthe
absolute alcohol.
saponification number is calculated.
NOTE 5—It has been found that 99% 2-propanol (isopropyl alcohol)
4.2 The titration end point can be detected either colori-
canbesubstitutedforthepurifiedethanolwithentirelysatisfactoryresults.
metrically (Method A) or potentiometrically (Method B).
This substitution is not permissible, however, in referee tests.
NOTE 6—This composition is available under the name of “U.S.
5. Significance and Use
Department ofTreasury Specially Denatured Formula 30 (Regulation No.
3-1938).” Formula 3A plus 5% methanol is an equivalent.
5.1 Petroleumproductscancontainadditivesthatreactwith
alkalitoformmetalsoaps.Fatsareexamplesofsuchadditives.
7.4 Aqueous Hydrochloric Acid Standard Solution (0.5
Also, certain used engine oils, especially from turbine or
M)—Standardize to detect molarity changes of 0.0005 by
internal combustion engines, can contain chemicals that will
titrating with standard alcoholic KOH solution (see 7.8 and
similarly react with alkali. The saponification number ex-
Note 7).
presses the amount of base that will react with1gof sample
NOTE7—Wheresaponificationnumbersbelowoneareexpected,better
whenheatedinaspecificmanner.Thisthengivesanestimation
precisioncanbeobtainedbysubstituting0.1 MKOHsolutionandHClfor
of the amount of acid present in the sample, that is, any free
the 0.5 M reagents in Sections 7, 8, 10, 17, and 19.
acid originally present plus any combined (for example, in
7.5 Butanone (Methyl Ethyl Ketone) ,technicalgrade.Store
esters) that have been converted to metal soaps during the
in dark or brown bottles. (Warning— See 4.1.)
heating procedure.
7.6 Naphtha, (Warning— Extremely flammable. Harmful
5.2 Saponification numbers are also used in setting product
if inhaled. Vapors can cause flash fire.) ASTM Precipitation
specifications for lubricants and additives.
Grade (or Petroleum Spirit-60/80 or hexanes) (Warning—
Combustible. Vapor harmful.) Petroleum spirit shall conform
METHOD A—COLOR INDICATOR TITRATION
to the current IP 136.
6. Apparatus
7.7 Phenolphthalein Solution, Neutralized—Dissolve 1.0 6
6.1 Erlenmeyer Flask and Condenser— An Erlenmeyer
0.1 g of phenolphthalein in 100 mL of alcohol (see 7.3).
flask,250or300-mLcapacity,alkali-resistant(seeNote3)and
Neutralize to faint pink color with dilute (0.1 M) alcoholic
(Warning—Causes severe burns; a recognized carcinogen;
KOH solution.
strong oxidizer—contact with other material can cause fire;
7.8 Alcoholic Potassium Hydroxide Standard Solution (0.5
hygroscopic ), to which is attached a straight or mushroom-
M)—Prepareapproximately0.5 MsolutionbydissolvingKOH
type reflux condenser. The straight-type condenser is fitted to
in the alcohol specified in 7.3.Allow the solution to settle in a
the flask with a ground-glass joint; the mushroom-type con-
dark place. Filter the solution, and allow to stand for 24 h
denser must fit loosely to permit venting of the flask. Water
before using.
reflux condensers can also be used instead of air condensers.
7.8.1 Alternatively prepare 0.5 or 0.1 M alcoholic KOH by
NOTE 3—Do not use scratched or etched Erlenmeyer flasks because
mixing a commercially available KOH ampule (which is
KOH will react with them. The glassware shall be chemically clean. It is
recommended that flasks be cleaned with chromic acid cleaning solution
(Alternatively, Nochromix or similar products can be used.)
Reagent Chemicals, American Chemical Society Specifications, American
6.2 Hot Plate—A suitable hot plate heated by either elec-
Chemical Society, Washington, DC. For Suggestions on the testing of reagents not
tricity or steam. (Warning—Thermal hazard; in addition to
listed by the American Chemical Society, see Annual Standards for Laboratory
other precautions, avoid contact with exposed skin.)
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
7. Reagents MD.
Available from the U.S. Bureau of Alcohol, Tobacco, and Firearms, Distilled
7.1 Purity of Reagents—Reagent grade chemicals shall be
Spirits and Tobacco Branch, 1200 Pennsylvania Avenue, NW, Washington, DC
used in all tests. Unless otherwise indicated, it is intended that 20226.
´1
D94 − 07 (2012)
carbonate free) with 95% alcohol. Using this type solution reached(Note14).Theendpointisreachedwhentheindicator
gives consistent blanks and does not give multiple breaks (see color is completely discharged and does not immediately
Note 8). reappear upon further dropwise addition of the indicator
solution. Record as V in 11.1.
NOTE 8—Because of the relatively large coefficient of cubic expansion
of organic liquids such as 2-propanol (isopropyl alcohol), the standard
NOTE 14—Avoid emulsification of titration mixture, but ensure phase
alcoholic solution has to be standardized at temperatures close to those
contact by swirling the flask vigorously as the end point is approached.
employed in the titrations of samples.
9. Sample
7.8.2 The KOH solutions shall be standardized by titrating
9.1 Using Practice D4057 (manual sampling) or Practice
with standard potassium hydrogen phthalate solution (see 7.9
D4177 (automatic sampling) as a guideline for obtaining a
and Note 8).
representativesample,makesurethattheportionofthesample
7.9 Potassium Hydrogen Phthalate—(C H KO ) 0.1 M
8 5 4
to be tested appears homogenous. Choose the size of the
Standard Solution —Weigh 2.0422 6 0.0002 g of potassium
sample so that the back-titration volume is from 40 to 80% of
hydrogen phthalate that has been dried at 110 6 5°C to a
the blank, but do not exceed a 20-g sample weight (see Note
constant weight into a 100-mL volumetric flask. Dissolve in
15).
reagent water. Some heating may be necessary to dissolve the
NOTE 15—The following sample sizes are suggested:
solid. Dilute to 100 mLwith distilled or deionized water, after
Saponification Number Sample Size, g
the solution has cooled.
181 to 400 1
7.10 Stoddard Solvent, technical grade. (Warning—
111 to 180 2
71 to 110 3
Extremely flammable. Harmful if inhaled.)
31 to 70 5
7.11 Xylene, reagent grade. (Warning—Extremely flam- 16 to 30 10
0to15 20
mable. Harmful if inhaled.)
10. Procedure
8. Blank Determinations
10.1 Weigh the specimen to the nearest 0.01 g (record as W
8.1 Perform a blank determination concurrently with each in 11.1), such as by difference, from a small beaker into the
set (see Note 9) (one or more) of samples as follows: measure Erlenmeyer flask. Add 25 6 1 mL of butanone or one of the
accurately from a buret or volumetric pipet (see Note 10) into alternative solvents (Warning—See 4.1), followed by 25 6
theErlenmeyerflask25 60.03mLofalcoholicKOHsolution 0.03 mL of alcoholic KOH solution (Warning—See 7.3)
and 256 1 mLof butanone (methylethyl-ketone) or one of the measuredaccuratelyfromaburetorvolumetricpipet(seeNote
alternative solvents. Connect the condenser to the flask, and 7).
heat for the same amount of time as that used for the sample
10.2 Dissolve the difficult to dissolve samples, such as
after refluxing begins. (Warning—The reflux condenser
lubricants and additives, first in 15 to 25 mL of Stoddard
shouldbeclampedsecurelytopreventitfromtippingoveronto
Solvent (Warning— See 7.10) or xylene (Warning—See
the hot plate with possible breakage of glassware. See also
7.11) before adding butanone (Warning—See 4.1).
Note 11. ) Immediately add 50 mL of ASTM precipitation
10.3 Connect the condenser to the flask and heat for 30 min
naphtha (Warning— See 7.6, also Note 12 and Note 13)by
afterrefluxingbegins(seeNote11).Immediatelyadd50mLof
cautiously pouring the naphtha down the condenser (discon-
ASTM precipitation naphtha (Warning—Do not pour naphtha
nectcondenserifmushroom-typeisused),andtitratetheblank
while the flask is on the hot plate) and (see 7.6) by cautiously
while hot, without reheating, with 0.5 M hydrochloric acid
pouring the naphtha down the condenser (see Note 12)
(HCl) using three drops of neutralized phenolphthalein indica-
(disconnect condenser if mushroom-type before adding the
tor solution.
naphtha).
NOTE 9—Run blank determinations in duplicate on samples requiring
10.4 Titrate the solution while hot (without reheating) with
the highest accuracy. The precision data are based on duplicate blank
0.5 M HCl using three drops of neutralized phenolphthalein
determinations. A single blank is sufficient for
...
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.
´1
Designation: D94 − 07 (Reapproved 2012) D94 − 07 (Reapproved 2012)
Designation: 136S1/98, 136S2/99
Standard Test Methods for
Saponification Number of Petroleum Products
This standard is issued under the fixed designation D94; 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.
ε NOTE—The Research Report number in 23.1 was corrected editorially in May 2015.
1. Scope
1.1 These test methods cover the determination of the amount of constituents in petroleum products such as lubricants,
additives, and transmission fluids that will saponify under the conditions of the test.
NOTE 1—Statements defining this test and its significance when applied to electrical insulating oils of mineral origin will be found in Guide D117.
Experience has shown that for transformer oils, Test Method D94, modified by use of 0.1 M KOH solution and 0.1 M HCl, is more suitable.
1.1.1 Two test methods are described: Method A—Color Indicator Titration (Sections 6 – 13), and Method B—Potentiometric
Titration (Sections 14 – 23).
1.2 Because compounds of sulfur, phosphorus, the halogens, and certain other elements that are sometimes added to petroleum
products also consume alkali and acids, the results obtained indicate the effect of these extraneous materials in addition to the
saponifiable material present. Results on products containing such materials, on used internal-combustion-engine crankcase oils,
and on used turbine oils must be interpreted with caution.
NOTE 2—The materials referred to above, which are not normally considered saponifiable matter, include inorganic or certain organic acids, most
nonalkali soaps, and so forth. The presence of such materials increases the saponification number above that of fatty saponifiable materials for which the
test method is primarily intended. The odor of hydrogen sulfide near the end of the back-titration in the saponification test is an indication that certain
types of reactive sulfur compounds are present in the sample. In the case of other reactive sulfur, chlorine, and phosphorus compounds and other
interfering materials, no simple indication is given during the test. A gravimetric determination of the actual amount of fatty acids is probably the most
reliable method for such compounds. Test Methods D128 or IP Method 284/86 can be used to determine fatty acids gravimetrically.
1.3 The values stated in SI units are to be regarded as the standard.
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 Sections 6, 7, 8, 10, 15, 16, 17, and 19.
2. Referenced Documents
2.1 ASTM Standards:
D117 Guide for Sampling, Test Methods, and Specifications for Electrical Insulating Oils of Petroleum Origin
D128 Test Methods for Analysis of Lubricating Grease
D1193 Specification for Reagent Water
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
D6792 Practice for Quality System in Petroleum Products and Lubricants Testing Laboratories
These test methods are under the jurisdiction of ASTM Committee D02 on Petroleum Products Products, Liquid Fuels, and Lubricants and are the direct responsibility
of Subcommittee D02.06 on Analysis of Liquid Fuels and Lubricants.
Current edition approved Nov. 1, 2012. Published November 2012. Originally approved in 1921. Last previous edition approved in 2007 as D94–07. DOI:
10.1520/D0094-07R12.10.1520/D0094-07R12E01.
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 ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
D94 − 07 (2012)
2.2 Energy Institute Standards:
IP 136 Method of Test for Saponification Number of Petroleum Products
IP 284 Method of Test for Fatty Acids
3. Terminology
3.1 Definitions:
3.1.1 saponification number, n—the number of milligrams of potassium hydroxide consumed by 1 g of a sample under the
conditions of the test.
Available from Institute of Petroleum, 61 New Cavendish St., London, W.I., England.Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR, U.K.,
http://www.energyinst.org.uk.
3.1.1.1 Discussion—
The value of the saponification number in these test methods can be affected by the presence of other alkali-reactive species, as
described in Note 2.
3.1.2 saponify, v—to hydrolyze a fat with alkali to form an alcohol and the salt of a fatty acid.
4. Summary of Test Method
4.1 A known mass of the sample is dissolved in a suitable solvent, such as butanone (methylethylketone), xylenes, or Stoddard
Solvent, or a combination thereof (Warning—Extremely flammable. Vapors can cause flash fire), and is heated with a known
amount of alcoholic potassium hydroxide (KOH). The excess alkali is titrated with standard acid, and the saponification number
is calculated.
4.2 The titration end point can be detected either colorimetrically (Method A) or potentiometrically (Method B).
5. Significance and Use
5.1 Petroleum products can contain additives that react with alkali to form metal soaps. Fats are examples of such additives.
Also, certain used engine oils, especially from turbine or internal combustion engines, can contain chemicals that will similarly
react with alkali. The saponification number expresses the amount of base that will react with 1 g of sample when heated in a
specific manner. This then gives an estimation of the amount of acid present in the sample, that is, any free acid originally present
plus any combined (for example, in esters) that have been converted to metal soaps during the heating procedure.
5.2 Saponification numbers are also used in setting product specifications for lubricants and additives.
METHOD A—COLOR INDICATOR TITRATION
6. Apparatus
6.1 Erlenmeyer Flask and Condenser— An Erlenmeyer flask, 250 or 300-mL capacity, alkali-resistant (see Note 3) and
(Warning—Causes severe burns; a recognized carcinogen; strong oxidizer—contact with other material can cause fire;
hygroscopic ), to which is attached a straight or mushroom-type reflux condenser. The straight-type condenser is fitted to the flask
with a ground-glass joint; the mushroom-type condenser must fit loosely to permit venting of the flask. Water reflux condensers
can also be used instead of air condensers.
NOTE 3—Do not use scratched or etched Erlenmeyer flasks because KOH will react with them. The glassware shall be chemically clean. It is
recommended that flasks be cleaned with chromic acid cleaning solution (Alternatively, Nochromix or similar products can be used.)
6.2 Hot Plate—A suitable hot plate heated by either electricity or steam. (Warning—Thermal hazard; in addition to other
precautions, avoid contact with exposed skin.)
7. Reagents
7.1 Purity of Reagents—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.
NOTE 4—Commercially available reagents may be used in place of laboratory preparations, provided they meet the specifications outlined.
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 Annual 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.
´1
D94 − 07 (2012)
7.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by
Type I, II, or III in Specification D1193.
7.3 Alcohol —95 % ethanol (Warning—Flammable. Denatured—Cannot be made nontoxic) (see Note 5) and (Warning—
Flammable) or 95 % ethanol to which has been added 10 volume % of methanol (see Note 5 and Note 6) or absolute alcohol.
NOTE 5—It has been found that 99 % 2-propanol (isopropyl alcohol) can be substituted for the purified ethanol with entirely satisfactory results. This
substitution is not permissible, however, in referee tests.
NOTE 6—This composition is available under the name of “U.S. Department of Treasury Specially Denatured Formula 30 (Regulation No. 3-1938).”
Formula 3A plus 5 % methanol is an equivalent.
7.4 Aqueous Hydrochloric Acid Standard Solution (0.5 M)—Standardize to detect molarity changes of 0.0005 by titrating with
standard alcoholic KOH solution (see 7.8 and Note 7).
NOTE 7—Where saponification numbers below one are expected, better precision can be obtained by substituting 0.1 M KOH solution and HCl for the
0.5 M reagents in Sections 7, 8, 10, 17, and 19.
7.5 Butanone (Methyl Ethyl Ketone) , technical grade. Store in dark or brown bottles. (Warning— See 4.1.)
7.6 Naphtha, (Warning— Extremely flammable. Harmful if inhaled. Vapors can cause flash fire.) ASTM Precipitation Grade
(or Petroleum Spirit-60/80 or hexanes) (Warning—Combustible. Vapor harmful.) Petroleum spirit shall conform to the current IP
136.
7.7 Phenolphthalein Solution, Neutralized—Dissolve 1.0 6 0.1 g of phenolphthalein in 100 mL of alcohol (see 7.3). Neutralize
to faint pink color with dilute (0.1 M) alcoholic KOH solution.
7.8 Alcoholic Potassium Hydroxide Standard Solution (0.5 M)—Prepare approximately 0.5 M solution by dissolving KOH in
the alcohol specified in 7.3. Allow the solution to settle in a dark place. Filter the solution, and allow to stand for 24 h before using.
7.8.1 Alternatively prepare 0.5 or 0.1 M alcoholic KOH by mixing a commercially available KOH ampule (which is carbonate
free) with 95 % alcohol. Using this type solution gives consistent blanks and does not give multiple breaks (see Note 8).
NOTE 8—Because of the relatively large coefficient of cubic expansion of organic liquids such as 2-propanol (isopropyl alcohol), the standard alcoholic
solution has to be standardized at temperatures close to those employed in the titrations of samples.
7.8.2 The KOH solutions shall be standardized by titrating with standard potassium hydrogen phthalate solution (see 7.9 and
Note 8).
7.9 Potassium Hydrogen Phthalate—(C H KO ) 0.1 M Standard Solution —Weigh 2.0422 6 0.0002 g of potassium hydrogen
8 5 4
phthalate that has been dried at 110 6 5°C to a constant weight into a 100-mL volumetric flask. Dissolve in reagent water. Some
heating may be necessary to dissolve the solid. Dilute to 100 mL with distilled or deionized water, after the solution has cooled.
7.10 Stoddard Solvent, technical grade. (Warning—Extremely flammable. Harmful if inhaled.)
7.11 Xylene, reagent grade. (Warning—Extremely flammable. Harmful if inhaled.)
8. Blank Determinations
8.1 Perform a blank determination concurrently with each set (see Note 9) (one or more) of samples as follows: measure
accurately from a buret or volumetric pipet (see Note 10) into the Erlenmeyer flask 25 6 0.03 mL of alcoholic KOH solution and
256 1 mL of butanone (methylethyl-ketone) or one of the alternative solvents. Connect the condenser to the flask, and heat for
the same amount of time as that used for the sample after refluxing begins. (Warning—The reflux condenser should be clamped
securely to prevent it from tipping over onto the hot plate with possible breakage of glassware. See also Note 11. ) Immediately
add 50 mL of ASTM precipitation naphtha (Warning— See 7.6, also Note 12 and Note 13) by cautiously pouring the naphtha
down the condenser (disconnect condenser if mushroom-type is used), and titrate the blank while hot, without reheating, with 0.5
M hydrochloric acid (HCl) using three drops of neutralized phenolphthalein indicator solution.
NOTE 9—Run blank determinations in duplicate on samples requiring the highest accuracy. The precision data are based on duplicate blank
determinations. A single blank is sufficient for routine work.
NOTE 10—If a volumetric pipet is used to measure the alcoholic KOH solution, wait 30 s after delivery to allow for complete drainage.
NOTE 11—Although standard procedure requires 30 min of reflux, some fats are readily saponified and complete saponification takes place within 10
min. On the other hand, difficult saponifiable materials require more than 2 h. Neither the shortened period nor the longer period should be used except
by mutual consent of the interested parties.
NOTE 12—Pouring 50 mL of naphtha down the condenser at the end of the saponification not only rinses the condenser but also cools the reaction
mixture.
NOTE 13—In the case of insulating oils, the addition of ASTM precipitation naphtha or petroleum spirit is not necessary.
8.2 After the indicator color has been discharged, add, dropwise, more indicator solution. If this addition of indicator restores
the color, continue the titration, making further dropwise additions of indicator, if necessary, until the end point is reached (Note
14). The end point is reached when the indicator color is completely discharged and does not immediately reappear upon further
dropwise addition of the indicator solution. Record as V in 11.1.
Available from the U.S. Bureau of Alcohol, Tobacco, and Firearms, Distilled Spirits and Tobacco Branch, 1200 Pennsylvania Avenue, NW, Washington, DC 20226.
´1
D94 − 07 (2012)
NOTE 14—Avoid emulsification of titration mixture, but ensure
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