ASTM D1123-22a

Standard Test Methods for Water in Engine Coolant Concentrate by the Karl Fischer Reagent Method

SIGNIFICANCE AND USE
5.1 The total apparent water in engine coolant concentrate as determined by Karl Fischer titrations consists of the following: (1) water present in the original glycol base; (2) water added (for example, inhibitor solutions); (3) water of hydration of inhibitors (for example, Na2B4O7·5H2O); (4) water formed in the chemical reaction between borate and ethylene glycol, producing boratediol condensate and water; and (5) quantitative interference by the reaction of the reagent with inhibitors such as tetraborate or sodium hydroxide.
SCOPE
1.1 These test methods cover the determination of the water present in new or unused glycol-based coolant concentrates using a volumetric (Test Method A) or an automatic coulometric titrator procedure (Test Method B).  
1.2 Many carbonyl compounds react slowly with the Fischer reagent, causing a fading end point and leading to high results. A modified Fischer reagent procedure is included that minimizes these undesirable and interfering reactions.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard does not purport to address all of the safety problems, 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 specific hazards statements see Sections 8 and 16.  
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

• Status: Published
• Publication Date: 31-Aug-2022
• ICS: 71.100.45 - Refrigerants and antifreezes
• Technical Committee: D15 - Engine Coolants and Related Fluids
• Drafting Committee: D15.04 - Chemical Properties

Relations

• Refers: ASTM E203-24 - Standard Test Method for Water Using Volumetric Karl Fischer Titration
• Effective Date: 01-Jan-2024
• Refers: ASTM D156-23 - Standard Test Method for Saybolt Color of Petroleum Products (Saybolt Chromometer Method)
• Effective Date: 01-Oct-2023
• Refers: ASTM D1176-14(2019) - Standard Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
• Effective Date: 01-Oct-2019
• Refers: ASTM D1176-14 - Standard Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
• Effective Date: 01-Apr-2014
• Refers: ASTM D156-12 - Standard Test Method for Saybolt Color of Petroleum Products (Saybolt Chromometer Method)
• Effective Date: 01-Nov-2012
• Refers: ASTM D1176-98(2008) - Standard Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
• Effective Date: 01-Apr-2008
• Refers: ASTM D156-07a - Standard Test Method for Saybolt Color of Petroleum Products (Saybolt Chromometer Method)
• Effective Date: 01-Dec-2007
• Refers: ASTM D156-07 - Standard Test Method for Saybolt Color of Petroleum Products (Saybolt Chromometer Method)
• Effective Date: 15-Jul-2007
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D156-02e1 - Standard Test Method for Saybolt Color of Petroleum Products (Saybolt Chromometer Method)
• Effective Date: 10-Nov-2002
• Refers: ASTM D156-02 - Standard Test Method for Saybolt Color of Petroleum Products (Saybolt Chromometer Method)
• Effective Date: 10-Nov-2002
• Refers: ASTM D156-00 - Standard Test Method for Saybolt Color of Petroleum Products (Saybolt Chromometer Method)
• Effective Date: 10-Apr-2000
• Refers: ASTM D1193-99e1 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D1193-99 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D1176-98(2002) - Standard Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
• Effective Date: 10-Apr-1998

Overview

ASTM D1123-22a: Standard Test Methods for Water in Engine Coolant Concentrate by the Karl Fischer Reagent Method is a globally recognized ASTM standard developed for determining water content in new or unused glycol-based engine coolant concentrates. Accurate measurement of water content is essential for quality control, product qualification, and performance monitoring of engine coolants. This standard outlines two methodologies for assessment: volumetric titration (Test Method A) and automatic coulometric titration (Test Method B), both using the Karl Fischer reagent. The results help manufacturers and laboratories ensure proper formulation and stability of coolant concentrates, supporting compliance with regulatory and quality system requirements.

Key Topics

• Karl Fischer Titration Methods: The standard details the use of the Karl Fischer reagent in two test methods:
  • Volumetric (Manual) Titration (Method A)
  • Automatic Coulometric Titration (Method B)
• Significance of Water Content in Coolants: The water content determined includes water from glycol base, added ingredients, inhibitors, hydration water in additives, and water generated from chemical reactions. The test methods also account for potential interfering reactions, especially those involving inhibitors.
• Modified Reagent Procedures: The standard addresses potential inaccuracies from carbonyl compounds and certain inhibitors by including modified titration procedures to minimize such effects.
• Precision and Repeatability: Guidance is provided on repeatability and reproducibility to assess the consistency and reliability of results.
• Interferences and Limitations: Interference factors-such as reactions with borate, sodium hydroxide, or inhibitors-are discussed, clarifying their impact on apparent water content outcomes.

Applications

• Quality Assurance in Manufacturing: Ensuring engine coolant concentrates adhere to specified water content for optimal engine protection, longevity, and antifreeze performance.
• Laboratory Testing and Product Qualification: Verification of new or unused coolant batches, supporting production validation and process control.
• Regulatory Compliance: Meeting industry and international requirements for engine coolants, including alignment with other relevant standards and specifications.
• Research and Development: Supporting formulation development and troubleshooting in new coolant formulations, especially for understanding the interaction between glycol, inhibitors, and water.

Related Standards

• ASTM D156 - Saybolt Color of Petroleum Products: For testing the color of coolants and related fluids.
• ASTM D1176 - Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes: Outlines best practices for sampling, which ensures accuracy in Karl Fischer testing.
• ASTM D1193 - Specification for Reagent Water: Specifies requirements for reagent water used in test methods.
• ASTM E203 - Water Using Volumetric Karl Fischer Titration: An alternative detailed method for water determination, referenced for additional information.

Practical Value

Implementing ASTM D1123-22a allows coolant manufacturers and testing laboratories to:

• Ensure product consistency and detect water contamination or formulation errors.
• Minimize engine corrosion, freezing, and overheating risks due to improper coolant water content.
• Satisfy customer, OEM, and regulatory demands for reliable engine coolant products.
• Address analytical challenges associated with interfering substances, improving result integrity through recognized, repeatable protocols.

Keywords

ASTM D1123-22a, engine coolant water content, Karl Fischer reagent, glycol-based coolant, volumetric titration, coulometric titration, quality control, coolant analysis, international standards, water determination in coolants.

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.
Designation: D1123 − 22a
Standard Test Methods for
Water in Engine Coolant Concentrate by the Karl Fischer
Reagent Method
This standard is issued under the fixed designation D1123; 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* D1176 Practice for Sampling and Preparing Aqueous Solu-
tions of Engine Coolants orAntirusts forTesting Purposes
1.1 These test methods cover the determination of the water
D1193 Specification for Reagent Water
present in new or unused glycol-based coolant concentrates
E203 Test Method for Water Using Volumetric Karl Fischer
using a volumetric (Test MethodA) or an automatic coulomet-
Titration
ric titrator procedure (Test Method B).
3. Terminology
1.2 Many carbonyl compounds react slowly with the Fis-
cher reagent, causing a fading end point and leading to high
3.1 Definitions of Terms Specific to This Standard:
results. A modified Fischer reagent procedure is included that
3.1.1 color end point—that point during the titration when
minimizes these undesirable and interfering reactions.
the color change from yellow to orange-red is sharp and easily
repeated. The orange-red color must persist for at least 30 s in
1.3 The values stated in SI units are to be regarded as
order to indicate an end point.
standard. No other units of measurement are included in this
3.1.1.1 Discussion—View the color by transmitted daylight
standard.
or by transmitted light from an artificial daylight lamp, such as
1.4 This standard does not purport to address all of the
one that complies with the specification given in Test Method
safety problems, if any, associated with its use. It is the
D156.
responsibility of the user of this standard to establish appro-
3.1.2 instrument end point—for the purpose of these tests,
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use. that point in the titration when two small platinum electrodes,
uponwhichapotentialof20 mVto50mVhasbeenimpressed,
For specific hazards statements see Sections 8 and 16.
1.5 This international standard was developed in accor- are depolarized by the addition of 0.05 mL of Fischer reagent
(6 mg of water/mL), causing a change of current flow of 10 µA
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the to 20 µA that persists for at least 30 s.
3.1.2.1 Discussion—Thisendpointissometimesincorrectly
Development of International Standards, Guides and Recom-
called the “dead stop,” which is the reverse of the above.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
4. Summary of Test Method
2. Referenced Documents
4.1 These test methods are based essentially on the reduc-
tion of iodine by sulfur dioxide in the presence of water. This
2.1 ASTM Standards:
reaction can be used quantitatively only when pyridine and an
D156 Test Method for Saybolt Color of Petroleum Products
alcohol are present to react as follows:
(Saybolt Chromometer Method)
I 1SO 1H O→SO 12HI (1)
2 2 2 3
These test methods are under the jurisdiction of ASTM Committee D15 on 4.2 In order to determine water, Karl Fischer reagent is
Engine Coolants and Related Fluids and are the direct responsibility of Subcom-
added to a solution of the sample in anhydrous high-purity
mittee D15.04 on Chemical Properties.
methanol until all water present has been consumed. This is
Current edition approved Sept. 1, 2022. Published September 2022. Originally
approved in 1950. Last previous edition approved in 2022 as D1123–22. DOI: evidenced by the persistence of the orange-red end point color,
10.1520/D1123-22A.
or alternatively by an indication on a galvanometer or similar
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
current-indicating device that records the depolarization of a
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
pair of noble metal electrodes. The reagent is standardized by
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the titration of water.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1123 − 22a
NOTE 1—It is believed that these methods give all the information
6.3 Instrument Depolarization Indicator, having an internal
required for determining the water in coolant formulations. Should
resistance of less than 5000 Ω and consisting of a means of
additional information on water determinations be needed, reference
impressing and showing a voltage of 20 mV to 50 mV across
should be made to Test Method E203.
theelectrodesandcapableofindicatingacurrentflowof10 µA
5. Significance and Use
to 20 µA by means of a galvanometer or radio tuning eye
circuit.
5.1 The total apparent water in engine coolant concentrate
as determined by Karl Fischer titrations consists of the follow-
6.4 Buret Assembly for Fischer reagent, consisting of a
ing: (1) water present in the original glycol base; (2) water
25 mL or 50 mL buret connected by means of glass (not
added (for example, inhibitor solutions); (3) water of hydration
rubber) connectors to a source of reagent; several types of
of inhibitors (for example, Na B O ·5H O); (4) water formed
2 4 7 2
automatic dispensing burets may be used. Since the reagent
in the chemical reaction between borate and ethylene glycol,
loses strength when exposed to moist air, all vents must be
producing boratediol condensate and water; and (5) quantita-
protected against atmospheric moisture by adequate drying
tive interference by the reaction of the reagent with inhibitors
tubes containing anhydrous calcium sulfate.All stopcocks and
such as tetraborate or sodium hydroxide.
joints should be lubricated with a lubricant not particularly
reactive with the reagent.
TEST METHOD A—VOLUMETRIC TITRATION
6.5 Weighing Bottle, of the Lunge or Grethen type, or
6. Apparatus
equivalent.
6.1 Titration Vessel—For color end point titrations, use a
6.6 Some laboratory equipment suppliers offer a Karl Fis-
100 mL or 250 mL volumetric flask, which need not be
cher apparatus.
calibrated. For instrument end point, a 250 mLflask fitted with
interchangeable electrodes (Fig. 1) may be used. This is
7. Reagents
particularly good for titrations of coolant concentrate that is
deeply colored from dye or any other cause. For permanently
7.1 Purity of Reagents—Reagent grade chemicals shall be
mounted assemblies, the vessel should have a capacity about
used in all tests. Unless otherwise indicated, it is intended that
equal to that of a 300 mL tall-form beaker and should be
all reagents shall conform to the specifications of the Commit-
provided with a tight-fitting closure to protect the sample and
tee onAnalytical Reagents of theAmerican Chemical Society,
reagent from atmospheric moisture, a stirrer, and a means of
where such specifications are available. Other grades may be
adding sample and reagents and removing spent reaction
used, provided it is first ascertained that the reagent is of
mixture. It is desirable to have a means for cooling the titration
sufficiently high purity to permit its use without lessening the
vessel to ice temperature.
accuracy of the determination.
6.2 Instrument Electrodes, platinum with a surface equiva-
7.2 Unless otherwise indicated, references to water shall be
lent to two No. 26 wires, 4.76 mm long. The wires should be
understood to mean reagent water, Type IV, conforming to
3 mmto8mmapartandsoinsertedinthevesselthattheliquid
Specification D1193.
will cover them.
7.3 Karl Fischer Reagent, pyridine-free, equivalent to 5 mg
of water/mL.
7.4 Methanol (Warning—See 8.1)—Anhydrous, high pu-
rity.
8. Hazards
8.1 Methanol—Poison; flammable; may be fatal or cause
blindness if swallowed; cannot be made non-poisonous; harm-
ful if inhaled.
9. Sampling
9.1 A representative sample of the contents of the original
container shall be obtained as directed in Practice D1176; even
if two phases are present, the water-insoluble phase should not
be separated.
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
NOTE 1—All dimensions in millimetres.
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
FIG. 1 Titration Flask Assembly MD.
D1123 − 22a
fromundertheburettip,wipethetipwithacleandryclothinadownward
10. Standardization of Reagent
motion.
10.1 Standardize the Fischer reagent, prior to use, by either
the color or instrument end point (see Section 3) method, using 12. Calculation
the procedure as used for titrating the sample (Section 11).
12.1 Calculatethetotalwatercontent(freeplusapparent)of
10.1.1 Add to each 250 mL flask 25 mL of anhydrous, high
the sample as follows:
purity methanol. Stir rapidly. Titrate with Karl Fischer reagent
Water, mass% 5 VF/10M (3)
according to 11.2.Add to the solution 0.09 g to 0.18 g of water
(to 60.1 mg). Titrate again and record the volume of titrant
where:
used. Repeat standardization one more time. If the relative
V = mL of Karl Fischer reagent required by the sample,
standard deviation of repeated standardizations is larger than
F = equivalency factor for Karl Fischer reagent, mg of
2 %, repeat the standardization steps.
water per mL of reagent, and
10.1.2 Calculate the equivalency factor of the reagent in
M = sample used, g.
terms of water content per millilitre as follows:
13. Precision and Bias
Equivalency factor, F, mg of water/mL 5 A/B (2)
13.1 Precision—The following data should be used for
where:
judging the acceptability of results (95 % probability):
A = mg of water used in the standardization, and
13.1.1 Repeatability—Duplicate results by the same opera-
B = Karl Fischer reagent required, mL.
tor should be considered suspect if they differ by more than the
following amount:
11. Procedure
Repeatability 0.5 mL of titrant
11.1 Introduce 30 mL to 50 mL of the anhydrous high-
13.1.2 Reproducibility—The result submitted by one labo-
purity methanol into a 250 mL Erlenmeyer flask, making sure,
ratory should not be considered suspect unless it differs from
if an instrument end point apparatus is used, that the electrodes
that of another laboratory by more than the following amount:
are covered by this amount of methanol. If the color end point
Water Content, % Reproducibility, % of mean
is to be determined, make up a second flask as well.
0.1to1.0 15
11.2 Adjust the stirrer, if any, to provide adequate mixing
1.0to10 5
without splashing. Titrate the mixture to the instrument end
13.2 Bias—Since there is no accepted reference material
point (3.1.2), or the color end point (3.1.1), with Karl Fischer
suitable for determining the bias for the procedure in this test
reagent.Ifthecolorendpointistobeobserved,titrateoneflask
method, bias has not been determined.
to match the first. Set aside the first flask as a comparison
standard for titrating the sample.
TE
...

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.
Designation: D1123 − 22 D1123 − 22a
Standard Test Methods for
Water in Engine Coolant Concentrate by the Karl Fischer
Reagent Method
This standard is issued under the fixed designation D1123; 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 Scope*
1.1 These test methods cover the determination of the water present in new or unused glycol-based coolant concentrates using a
manualvolumetric (Test Method A) or an automatic (Test Method B) coulometric titrator procedure.procedure (Test Method B).
1.2 Many carbonyl compounds react slowly with the Fischer reagent, causing a fading end point and leading to high results. A
modified Fischer reagent procedure is included that minimizes these undesirable and interfering reactions.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety problems, 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 specific hazards statements see Sections 8 and 16.
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.
2. Referenced Documents
2.1 ASTM Standards:
D156 Test Method for Saybolt Color of Petroleum Products (Saybolt Chromometer Method)
D1176 Practice for Sampling and Preparing Aqueous Solutions of Engine Coolants or Antirusts for Testing Purposes
D1193 Specification for Reagent Water
E203 Test Method for Water Using Volumetric Karl Fischer Titration
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 color end point—that point during the titration when the color change from yellow to orange-red is sharp and easily repeated.
The orange-red color must persist for at least 30 s in order to indicate an end point.
These test methods are under the jurisdiction of ASTM Committee D15 on Engine Coolants and Related Fluids and are the direct responsibility of Subcommittee D15.04
on Chemical Properties.
Current edition approved March 1, 2022Sept. 1, 2022. Published April 2022September 2022. Originally approved in 1950. Last previous edition approved in 20152022
as D1123 – 99D1123(2015).–22. DOI: 10.1520/D1123-22.10.1520/D1123-22A.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1123 − 22a
3.1.1.1 Discussion—
View the color by transmitted daylight or by transmitted light from an artificial daylight lamp, such as one that complies with the
specification given in Test Method D156.
3.1.2 instrument end point—for the purpose of these tests, that point in the titration when two small platinum electrodes, upon
which a potential of 20 mV to 50 mV has been impressed, are depolarized by the addition of 0.05 mL of Fischer reagent (6 mg
of water/mL), causing a change of current flow of 10 μA to 20 μA that persists for at least 30 s.
3.1.2.1 Discussion—
This end point is sometimes incorrectly called the “dead stop,” which is the reverse of the above.
4. Summary of Test Method
4.1 These test methods are based essentially on the reduction of iodine by sulfur dioxide in the presence of water. This reaction
can be used quantitatively only when pyridine and an alcohol are present to react as follows:
I 1SO 1H O→SO 12HI (1)
2 2 2 3
4.2 In order to determine water, Karl Fischer reagent is added to a solution of the sample in anhydrous high-purity methanol until
all water present has been consumed. This is evidenced by the persistence of the orange-red end point color, or alternatively by
an indication on a galvanometer or similar current-indicating device that records the depolarization of a pair of noble metal
electrodes. The reagent is standardized by the titration of water.
D1123 − 22a
NOTE 1—It is believed that these methods give all the information required for determining the water in coolant formulations. Should additional
information on water determinations be needed, reference should be made to Test Method E203.
5. Significance and Use
5.1 The total apparent water in engine coolant concentrate as determined by Karl Fischer titrations consists of the following: (1)
water present in the original glycol base; (2) water added (for example, inhibitor solutions); (3) water of hydration of inhibitors
(for example, Na B O ·5H O); (4) water formed in the chemical reaction between borate and ethylene glycol, producing boratediol
2 4 7 2
condensate and water; and (5) quantitative interference by the reaction of the reagent with inhibitors such as tetraborate or sodium
hydroxide.
TEST METHOD A—MANUALA—VOLUMETRIC TITRATION
6. Apparatus
6.1 Titration Vessel—For color end point titrations, use a 100 mL or 250 mL volumetric flask, which need not be calibrated. For
instrument end point, a 250 mL flask fitted with interchangeable electrodes (Fig. 1) may be used. This is particularly good for
titrations of coolant concentrate that is deeply colored from dye or any other cause. For permanently mounted assemblies, the
vessel should have a capacity about equal to that of a 300 mL tall-form beaker and should be provided with a tight-fitting closure
to protect the sample and reagent from atmospheric moisture, a stirrer, and a means of adding sample and reagents and removing
spent reaction mixture. It is desirable to have a means for cooling the titration vessel to ice temperature.
6.2 Instrument Electrodes, platinum with a surface equivalent to two No. 26 wires, 4.76 mm long. The wires should be 3 mm to
8 mm apart and so inserted in the vessel that the liquid will cover them.
6.3 Instrument Depolarization Indicator, having an internal resistance of less than 5000 Ω and consisting of a means of impressing
and showing a voltage of 20 mV to 50 mV across the electrodes and capable of indicating a current flow of 10 μA to 20 μA by
means of a galvanometer or radio tuning eye circuit.
6.4 Buret Assembly for Fischer reagent, consisting of a 25 mL or 50 mL buret connected by means of glass (not rubber) connectors
to a source of reagent; several types of automatic dispensing burets may be used. Since the reagent loses strength when exposed
NOTE 1—All dimensions in millimetres.
FIG. 1 Titration Flask Assembly
D1123 − 22a
to moist air, all vents must be protected against atmospheric moisture by adequate drying tubes containing anhydrous calcium
sulfate. All stopcocks and joints should be lubricated with a lubricant not particularly reactive with the reagent.
6.5 Weighing Bottle, of the Lunge or Grethen type, or equivalent.
6.6 Some laboratory equipment suppliers offer a Karl Fischer apparatus.
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.
7.2 Unless otherwise indicated, references to water shall be understood to mean reagent water, Type IV, conforming to
Specification D1193.
7.3 Karl Fischer Reagent, pyridine-free, equivalent to 5 mg of water/mL.
7.4 Methanol (Warning—See 8.1)—Anhydrous, high purity.
8. Hazards
8.1 Methanol—Poison; flammable; may be fatal or cause blindness if swallowed; cannot be made non-poisonous; harmful if
inhaled.
9. Sampling
9.1 A representative sample of the contents of the original container shall be obtained as directed in Practice D1176; even if two
phases are present, the water-insoluble phase should not be separated.
10. Standardization of Reagent
10.1 Standardize the Fischer reagent, prior to use, by either the color or instrument end point (see Section 3) method, using the
procedure as used for titrating the sample (Section 11).
10.1.1 Add to each 250 mL flask 25 mL of anhydrous, high purity methanol. Stir rapidly. Titrate with Karl Fischer reagent
according to 11.2. Add to the solution 0.09 g to 0.18 g of water (to 60.1 mg). Titrate again and record the volume of titrant used.
Repeat standardization one more time. If the relative standard deviation of repeated standardizations is larger than 2 %, repeat the
standardization steps.
10.1.2 Calculate the equivalency factor of the reagent in terms of water content per millilitre as follows:
Equivalency factor, F, mg of water/mL 5 A/B (2)
where:
A = mg of water used in the standardization, and
B = Karl Fischer reagent required, mL.
11. Procedure
11.1 Introduce 30 mL to 50 mL of the anhydrous high-purity methanol into a 250 mL Erlenmeyer flask, making sure, if an
instrument end point apparatus is used, that the electrodes are covered by this amount of methanol. If the color end point is to be
determined, make up a second flask as well.
Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by
the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National
Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
D1123 − 22a
11.2 Adjust the stirrer, if any, to provide adequate mixing without splashing. Titrate the mixture to the instrument end point (3.1.2),
or the color end point (3.1.1), with Karl Fischer reagent. If the color end point is to be observed, titrate one flask to match the first.
Set aside the first flask as a comparison standard for titrating the sample.
11.3 To the titration mixture thus prepared, add an amount of sample as indicated in Table 1. Exercise care when the sample is
transferred so that water is not absorbed from the air, particularly under conditions of high humidity. Again, titrate the mixture with
Karl Fischer reagent to the same instrument or color end point previously employed. Record the amount of reagent used to titrate
the water in the sample.
NOTE 2—When using the volumetric flask-type titration vessel in humid climate, place a piece of thin paraffin wax over the mouth of the vessel. Provide
a small hole for introducing the buret tip. In less humid climates it is sufficient to lower the tip of the buret deeply into the long neck of the titration flask.
NOTE 3—In titrating with the volumetric flask-type titration vessel, avoid wetting the stopper and upper end of the flask with either the reagent or the
sample solvent. Each time the titration is interrupted, touch the buret tip to the neck of the flask to remove droplets which, if not
...