ASTM E1064-24

Standard Test Method for Water in Organic Liquids by Coulometric Karl Fischer Titration

SIGNIFICANCE AND USE
4.1 The coulometric technique is especially suited for determining low concentrations of water in organic liquids that would yield small titers by the Karl Fischer volumetric procedure. The precision and accuracy of the coulometric technique decreases for concentrations of water much greater than 2.0 % because of the difficulty in measuring the small size of sample required. The test method assumes 100 % efficiency of coulombs in iodine production. Provision is made for verifying this efficiency. (See Table 1 and Note 5.)
SCOPE
1.1 This test method covers the determination of water from 0 % to 2.0 % mass in most liquid organic chemicals, with Karl Fischer reagent, using an automated coulometric titration procedure. Use of this test method is not applicable for liquefied gas products such as Liquid Petroleum Gas (LPG), Butane, Propane, Liquid Natural Gas (LNG), etc.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 Review the current Safety Data Sheets (SDS) for detailed information concerning toxicity, first-aid procedures, handling, and safety precautions.  
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. Specific precautionary statements are given in Section 8.  
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-Dec-2023
• ICS: 71.080.01 - Organic chemicals in general
• Technical Committee: D16 - Aromatic, Industrial, Specialty and Related Chemicals
• Drafting Committee: D16.04 - Instrumental Analysis

Relations

• Replaces: ASTM E1064-23 - Standard Test Method for Water in Organic Liquids by Coulometric Karl Fischer Titration
• Effective Date: 01-Jan-2024
• Refers: ASTM D4672-24 - Standard Test Method for Polyurethane Raw Materials: Determination of Water Content of Polyols
• Effective Date: 01-Feb-2024
• Refers: ASTM E203-24 - Standard Test Method for Water Using Volumetric Karl Fischer Titration
• Effective Date: 01-Jan-2024
• Refers: ASTM E203-23 - Standard Test Method for Water Using Volumetric Karl Fischer Titration
• Effective Date: 15-Jul-2023
• Refers: ASTM D4672-18 - Standard Test Method for Polyurethane Raw Materials: Determination of Water Content of Polyols
• Effective Date: 01-Apr-2018
• Referred By: ASTM D7785-21 - Standard Practice for Water in Lint Cotton by Oven Evaporation Combined with Volumetric Karl Fischer Titration
• Effective Date: 01-Jan-2024
• Referred By: ASTM D6304-20 - Standard Test Method for Determination of Water in Petroleum Products, Lubricating Oils, and Additives by Coulometric Karl Fischer Titration
• Effective Date: 01-Jan-2024
• Referred By: ASTM D5798-21 - Standard Specification for Ethanol Fuel Blends for Flexible-Fuel Automotive Spark-Ignition Engines
• Effective Date: 01-Jan-2024
• Referred By: ASTM D7618-13(2021) - Standard Specification for Ethyl Tertiary-Butyl Ether (ETBE) for Blending with Aviation Spark-Ignition Engine Fuel
• Effective Date: 01-Jan-2024
• Referred By: ASTM E2470-22 - Standard Specification for Polyester Grade Ethylene Glycol
• Effective Date: 01-Jan-2024
• Referred By: ASTM D2699-23a - Standard Test Method for Research Octane Number of Spark-Ignition Engine Fuel
• Effective Date: 01-Jan-2024
• Referred By: ASTM E202-18 - Standard Test Methods for Analysis of Ethylene Glycols and Propylene Glycols
• Effective Date: 01-Jan-2024
• Referred By: ASTM D5983-21 - Standard Specification for Methyl Tertiary-Butyl Ether (MTBE) for Blending With Gasolines for Use as Automotive Spark-Ignition Engine Fuel
• Effective Date: 01-Jan-2024
• Referred By: ASTM D2359-19 - Standard Specification for Refined Benzene-535
• Effective Date: 01-Jan-2024
• Referred By: ASTM D5501-20 - Standard Test Method for Determination of Ethanol and Methanol Content in Fuels Containing Greater than 20 % Ethanol by Gas Chromatography
• Effective Date: 01-Jan-2024

Overview

ASTM E1064-24: Standard Test Method for Water in Organic Liquids by Coulometric Karl Fischer Titration is an international standard developed by ASTM International. This method outlines a procedure for determining water content from 0% to 2.0% by mass in most liquid organic chemicals using coulometric Karl Fischer titration. The technique is particularly effective for detecting low concentrations of water that may not be suitable for traditional volumetric Karl Fischer methods. This standard is not applicable to liquefied gases such as LPG, butane, propane, or LNG.

Implementing ASTM E1064-24 enables precise water analysis in organic liquids, supporting quality control, product validation, and regulatory compliance in industries where dryness is critical.

Key Topics

• Coulometric Karl Fischer Titration: This standard method utilizes electrolytically generated iodine to react stoichiometrically with the water present in the sample. The process is automated, efficient, and especially suitable for low water levels.
• Scope of Application: Suitable for most liquid organic chemicals, but specifically excludes liquefied gases due to sample handling and measurement limitations.
• Precision and Limitations: Provides optimal precision and accuracy for samples with water concentrations up to 2.0% by mass. The technique may not be suitable for higher concentrations due to diminished accuracy in small sample measurements.
• Safety and Quality Assurance: Users must consult relevant Safety Data Sheets (SDS) and adhere to laboratory safety protocols. The laboratory should maintain robust quality control systems for reliable and reproducible results.

Applications

ASTM E1064-24 is widely utilized across various chemical and industrial sectors for routine water determination in organic solvents, specialty chemicals, and raw materials. Applications include:

• Quality Control of Raw Materials: Ensuring organic liquids meet moisture specifications is crucial for product consistency and downstream processing.
• Research and Development: Supports formulation studies, stability testing, and analytical research by accurately quantifying trace water.
• Production and Manufacturing: Facilitates ongoing in-process water determination in chemical production environments.
• Regulatory Compliance: Provides documented, standardized procedures that support compliance with national and international regulations regarding product quality.

By specifying pyridine-free reagents, the latest revision enhances laboratory safety, reduces toxicity, and aligns with modern instrument manufacturers' recommendations.

Related Standards

• ASTM D1193: Specification for Reagent Water - Ensures water used in analytical work meets required purity criteria.
• ASTM D4672: Standard Test Method for Water Content of Polyols - Employs Karl Fischer titration in polyurethane industry applications.
• ASTM D6809: Guide for Quality Control of Aromatic Hydrocarbons - Offers procedures supporting quality control and assurance for aromatic chemicals.
• ASTM E203: Standard Test Method for Water Using Volumetric Karl Fischer Titration - Defines the traditional volumetric determination approach.

These related standards enhance laboratory practice by providing complementary methods and guidelines for water determination, quality assurance, and statistical analysis in chemical testing.

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Keywords: coulometric Karl Fischer, water determination, organic liquids, ASTM E1064-24, pyridine-free, chemical analysis, quality control, laboratory standard, moisture analysis, SI units compliance.

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: E1064 − 24
Standard Test Method for
Water in Organic Liquids by Coulometric Karl Fischer
Titration
This standard is issued under the fixed designation E1064; 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.
1. Scope* D6809 Guide for Quality Control and Quality Assurance
Procedures for Aromatic Hydrocarbons and Related Ma-
1.1 This test method covers the determination of water from
terials
0 % to 2.0 % mass in most liquid organic chemicals, with Karl
E180 Practice for Determining the Precision of ASTM
Fischer reagent, using an automated coulometric titration
Methods for Analysis and Testing of Industrial and Spe-
procedure. Use of this test method is not applicable for
cialty Chemicals (Withdrawn 2009)
liquefied gas products such as Liquid Petroleum Gas (LPG),
E203 Test Method for Water Using Volumetric Karl Fischer
Butane, Propane, Liquid Natural Gas (LNG), etc.
Titration
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
3. Summary of Test Method
standard.
3.1 This test method is based on the Karl Fischer reaction
1.3 Review the current Safety Data Sheets (SDS) for de-
for determining water—the reduction of iodine by sulfur
tailed information concerning toxicity, first-aid procedures,
dioxide in the presence of water to form sulfur trioxide and
handling, and safety precautions.
hydriodic acid. The reaction becomes quantitative only when
1.4 This standard does not purport to address all of the organic base and methanol or other alcohol are present. Unlike
the volumetric Karl Fischer reagents that include iodine, the
safety problems, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- coulometric technique electrolytically generates iodine, with
10.71 C of generating current corresponding to 1 mg of water
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use. in accordance with Faraday’s law.
Specific precautionary statements are given in Section 8.
4. Significance and Use
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4.1 The coulometric technique is especially suited for de-
ization established in the Decision on Principles for the
termining low concentrations of water in organic liquids that
Development of International Standards, Guides and Recom-
would yield small titers by the Karl Fischer volumetric
mendations issued by the World Trade Organization Technical
procedure. The precision and accuracy of the coulometric
Barriers to Trade (TBT) Committee.
technique decreases for concentrations of water much greater
than 2.0 % because of the difficulty in measuring the small size
2. Referenced Documents
of sample required. The test method assumes 100 % efficiency
of coulombs in iodine production. Provision is made for
2.1 ASTM Standards:
verifying this efficiency. (See Table 1 and Note 5.)
D1193 Specification for Reagent Water
D4672 Test Method for Polyurethane Raw Materials: Deter-
5. Interferences
mination of Water Content of Polyols
5.1 Interfering substances are the same as are encountered
in the volumetric Karl Fischer titration. A detailed discussion
of interfering substances can be found in the treatise on
This test method is under the jurisdiction of ASTM Committee D16 on
Aromatic, Industrial, Specialty and Related Chemicals and is the direct responsi-
“Aquametry.”
bility of Subcommittee D16.04 on Instrumental Analysis.
Current edition approved Jan. 1, 2024. Published January 2024. Originally
approved in 1985. Last previous edition approved in 2023 as E1064 – 23. DOI:
10.1520/E1064-24. The last approved version of this historical standard is referenced on
For referenced ASTM standards, visit the ASTM website, www.astm.org, or www.astm.org.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM J. Mitchell, Jr. and D. M. Smith, “Aquametry”—A Treatise on Methods for the
Standards volume information, refer to the standard’s Document Summary page on Determination of Water, Part III—The Karl Fischer Reagent, 2nd Ed., J. Wiley and
the ASTM website. Sons, Inc., New York, NY 1990.
*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
E1064 − 24
TABLE 1 Sample Size Estimation
cal Society, where such specifications are available. Other
Expected Water Content Sample Size, mL grades may be used, provided it is first ascertained that the
0 mg ⁄kg to 500 mg/kg 5 reagent is of sufficiently high purity to permit its use without
500 mg ⁄kg to 1000 mg/kg 2
lessening the accuracy of the determination.
1000 mg ⁄kg to 2000 mg/kg 1
0.2 % mass to 0.5 % mass 0.5
7.2 Purity of Water—Unless otherwise indicated, reference
0.5 % mass to 2.0 % mass 0.1
to water shall be understood to mean Type I or Type II reagent
water, conforming to Specification D1193.
7.3 Karl Fischer Reagents—Commercial pyridine-free cou-
5.2 Test Method E203 discusses organic compounds in
lometric KF reagents and reagent systems of various types are
which water may be determined directly and compounds in
available for use with autotitrators for water determination.
which water cannot be determined directly, but in which
Coulometric titrations normally require two reagent solutions.
interferences may be eliminated by suitable chemical reactions.
An anolyte or solvent titration solution and a catholyte or
generator titrant solution. However, now reagents can be
6. Apparatus
purchased in one or two component reagent systems. A one
6.1 Automatic Titrator, consisting of a control unit, titration
component reagent system contains all the components re-
vessel, dual platinum sensing electrode, generator assembly,
quired for a Karl Fischer titration in a single solution. A two
and magnetic stirrer. The instrument is designed to coulometri-
component system incorporates separate solutions for the
cally generate iodine that reacts stoichiometrically with the
solvent and titrant.
water present in the sample solution. The coulombs of elec-
tricity required to generate the reagent are converted to NOTE 2—Two good references on pyridine-free reagents are the
®7
Hydranal Manual-Eugen Schotz Reagents for Karl Fischer Titration,
micrograms of water, which is obtained as a direct digital
from Riedel-deHaen (www.rdhlab.de) or Sigma Aldrich (www.sigma-
readout.
aldrich.com) and Moisture Measurement by Karl Fischer Titrimetry, 2nd
ed., by GFS Chemicals, Inc., January 2004.
6.2 Syringe, 50 mL, fitted with an 115 mm hypodermic
needle for removing excess solution from the titration chamber.
7.3.1 Generator Titrant Solution (catholyte), containing
iodine, sulfur dioxide, other organic base and methanol or other
NOTE 1—Rinse all glass syringes and needles with anhydrous acetone
alcohol to provide iodine in the reaction mixture.
after cleaning, then dry in an oven at 100 °C for at least 1 h and store in
a desiccator. Plastic syringes shall be disposed of following use.
7.3.2 Solvent Titration Solution (anolyte), prepared as per
instrument specifications.
6.3 Syringe, 20 mL, fitted with an 115 mm hypodermic
7.3.3 Neutralizing Solution, methanol containing approxi-
needle for introduction of neutralizing solution into the titration
mately 20 mg H O/mL.
chamber (see Note 1).
6.4 Syringes, 1 mL and 5 mL, fitted with 115 mm hypoder-
8. Safety Precautions
mic needles for introduction of samples into titration chamber
(see Note 1). 8.1 The reagents contain one or more of the following:
iodine, other organic base, sulfur dioxide, and methanol or
6.5 Syringe, 5 μL, fitted with 115 mm hypodermic needle
other alcohol. Wear chemical resistant gloves when mixing the
for standardization of instrument (see Note 1).
reagents and removing solution from the titration chamber.
6.6 Fluorocarbon Sealing Grease or TFE-Fluorocarbon, to
Care must be exercised to avoid inhalation of reagent vapors,
seal the titration chamber against atmospheric moisture.
or direct contact of the reagent with the skin.
6.7 Septa, to seal sample port but allow introduction of
samples by a needle with a minimum of moisture contamina- 9. Sampling
tion. Replace serum caps and septa as required to prevent air
9.1 Because of the low concentration of water to be
leakage as indicated by instrument drift.
measured, maximum care must be exercised at all times to
6.8 Serum Bottles. avoid contaminating the sample with moisture from the sample
container, the atmosphere, or transfer equipment.
6.9 Oven, temperature 100 °C 6 5 °C.
9.1.1 Dry the sample bottles and caps overnight in an oven
6.10 Dessicator, standard laboratory type with color change
at 100 °C before using. Allow to cool in a desiccator before
indicator.
filling and sealing.
6.11 Analytical Balance, capable of weighing to 60.0001 g.
9.1.2 Fill the sample bottle as rapidly as possible to within
25 mm of the top and immediately seal.
7. Reagents
7.1 Purity of Reagents—Unless otherwise indicated, it is
intended that all reagents shall conform to the specifications of
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
the Committee on Analytical Reagents of the American Chemi-
Standard-Grade Reference Materials, 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,
Basic references to the automatic coulometric titrator: M. T. Kelley, R. W. U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
Stelzner, W. R. Laing, and D. J. Fisher, Analytical Chemistry 31, No. 2, 220 (1959) copeial Convention, Inc. (USPC), Rockville, MD.
7 ®
and A. W. Meyer, Jr. and C. M. Boyd, Analytical Chemistry 31, No. 2, 215 (1959). Hydranal is a registered trademark of Sigma-Aldrich, Inc, St. Louis, MO.
E1064 − 24
9.2 Remove the test specimens for analysis from the sample determine the exact sample mass. Allow the titration to proceed
bottle with a dry hypodermic syringe. Inject dry nitrogen into until the end-point is indicated. Record the micrograms of
the sample bottle with the syringe to displace the sample that water determined.
is removed.
NOTE 6—After numerous analyses, the level of solvent accumulated in
the titration chamber may have to be reduced. This can be accomplished
10. Preparation of Apparatus
with a 50 mL syringe or by partially draining the solution if the titration
chamber is provided with a stopcock. Discard the solution and replace
10.1 Clean, dry, and assemble the titration chamber as
with fresh titration solution if a stable reading cannot be obtained.
directed in the manufacturer’s instructions. Use fluorocarbon
NOTE 7—Replace the generator solution when it becomes yellow and a
grease or TFE-fluorocarbon to seal the upper and lower stable reading cannot be obtained.
sections of the chamber from atmospheric moisture. Connect
13. Calculation
the leads from the sensing and generator electrodes to the
titra
...

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: E1064 − 23 E1064 − 24
Standard Test Method for
Water in Organic Liquids by Coulometric Karl Fischer
Titration
This standard is issued under the fixed designation E1064; 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.
1. Scope*
1.1 This test method covers the determination of water from 0 % to 2.0 % mass in most liquid organic chemicals, with Karl Fischer
reagent, using an automated coulometric titration procedure. Use of this test method is not applicable for liquefied gas products
such as Liquid Petroleum Gas (LPG), Butane, Propane, Liquid Natural Gas (LNG), etc.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 Review the current Safety Data Sheets (SDS) for detailed information concerning toxicity, first-aid procedures, handling, and
safety precautions.
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. Specific precautionary statements are given in Section 8.
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:
D1193 Specification for Reagent Water
D4672 Test Method for Polyurethane Raw Materials: Determination of Water Content of Polyols
D6809 Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials
E180 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Specialty Chemicals
(Withdrawn 2009)
E203 Test Method for Water Using Volumetric Karl Fischer Titration
3. Summary of Test Method
3.1 This test method is based on the Karl Fischer reaction for determining water—the reduction of iodine by sulfur dioxide in the
This test method is under the jurisdiction of ASTM Committee D16 on Aromatic, Industrial, Specialty and Related Chemicals and is the direct responsibility of
Subcommittee D16.04 on Instrumental Analysis.
Current edition approved July 15, 2023Jan. 1, 2024. Published August 2023January 2024. Originally approved in 1985. Last previous edition approved in 20162023 as
E1064 – 16.E1064 – 23. DOI: 10.1520/E1064-23.10.1520/E1064-24.
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.
The last approved version of this historical standard is referenced on www.astm.org.
*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
E1064 − 24
presence of water to form sulfur trioxide and hydriodic acid. The reaction becomes quantitative only when pyridine or other
organic base and methanol or other alcohol are present. Unlike the volumetric Karl Fischer reagents that include iodine, the
coulometric technique electrolytically generates iodine, with 10.71 C of generating current corresponding to 1 mg of water in
accordance with Faraday’s law.
4. Significance and Use
4.1 The coulometric technique is especially suited for determining low concentrations of water in organic liquids that would yield
small titers by the Karl Fischer volumetric procedure. The precision and accuracy of the coulometric technique decreases for
concentrations of water much greater than 2.0 % because of the difficulty in measuring the small size of sample required. The test
method assumes 100 % efficiency of coulombs in iodine production. Provision is made for verifying this efficiency. (See Table 1
and Note 5.)
5. Interferences
5.1 Interfering substances are the same as are encountered in the volumetric Karl Fischer titration. A detailed discussion of
interfering substances can be found in the treatise on “Aquametry.”
5.2 Test Method E203 discusses organic compounds in which water may be determined directly and compounds in which water
cannot be determined directly, but in which interferences may be eliminated by suitable chemical reactions.
6. Apparatus
6.1 Automatic Titrator, consisting of a control unit, titration vessel, dual platinum sensing electrode, generator assembly, and
magnetic stirrer. The instrument is designed to coulometrically generate iodine that reacts stoichiometrically with the water present
in the sample solution. The coulombs of electricity required to generate the reagent are converted to micrograms of water, which
is obtained as a direct digital readout.
6.2 Syringe, 50 mL, fitted with an 115 mm hypodermic needle for removing excess solution from the titration chamber.
NOTE 1—Rinse all glass syringes and needles with anhydrous acetone after cleaning, then dry in an oven at 100 °C for at least 1 h and store in a desiccator.
Plastic syringes shall be disposed of following use.
6.3 Syringe, 20 mL, fitted with an 115 mm hypodermic needle for introduction of neutralizing solution into the titration chamber
(see Note 1).
6.4 Syringes, 1 mL and 5 mL, fitted with 115 mm hypodermic needles for introduction of samples into titration chamber (see Note
1).
6.5 Syringe, 5 μL, fitted with 115 mm hypodermic needle for standardization of instrument (see Note 1).
6.6 Fluorocarbon Sealing Grease or TFE-Fluorocarbon, to seal the titration chamber against atmospheric moisture.
TABLE 1 Sample Size Estimation
Expected Water Content Sample Size, mL
0 mg ⁄kg to 500 mg/kg 5
500 mg ⁄kg to 1000 mg/kg 2
1000 mg ⁄kg to 2000 mg/kg 1
0.2 to 0.5 % mass 0.5
0.2 % mass to 0.5 % mass 0.5
0.5 to 2.0 % mass 0.1
0.5 % mass to 2.0 % mass 0.1
J. Mitchell, Jr. and D. M. Smith, “Aquametry”—A Treatise on Methods for the Determination of Water, Part III—The Karl Fischer Reagent, 2nd Ed., J. Wiley and Sons,
Inc., New York, NY 1990.
Basic references to the automatic coulometric titrator: M. T. Kelley, R. W. Stelzner, W. R. Laing, and D. J. Fisher, Analytical Chemistry 31, No. 2, 220 (1959) and A.
W. Meyer, Jr. and C. M. Boyd, Analytical Chemistry 31, No. 2, 215 (1959).
E1064 − 24
6.7 Septa, to seal sample port but allow introduction of samples by a needle with a minimum of moisture contamination. Replace
serum caps and septa as required to prevent air leakage as indicated by instrument drift.
6.8 Serum Bottles.
6.9 Oven, temperature 100 °C 6 5 °C.
6.10 Dessicator, standard laboratory type with color change indicator.
6.11 Analytical Balance, capable of weighing to 60.0001 g.
7. Reagents
7.1 Purity of Reagents—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 Purity of Water—Unless otherwise indicated, reference to water shall be understood to mean Type I or Type II reagent water,
conforming to Specification D1193.
7.3 Karl Fischer Reagents—Commercial coulometricpyridine-free coulometric KF reagents and reagent systems of various types
are available for use with autotitrators for water determination. Traditionally, pyridine was the organic base used in KF reagents.
Pyridine-free formulations are available and are preferred by most KF instrument manufacturers for use with their equipment. The
pyridine-free reagents are less toxic, less odorous, and more stable than those containing pyridine. The use of pyridine-free reagents
is recommended whenever possible. Coulometric titrations normally require two reagent solutions. An anolyte or solvent titration
solution and a catholyte or generator titrant solution. However, now reagents can be purchased in one or two component reagent
systems. A one component reagent system contains all the components required for a Karl Fischer titration in a single solution.
A two component system incorporates separate solutions for the solvent and titrant.
®7
NOTE 2—Two good references on pyridine-free reagents are the Hydranal Manual-Eugen Schotz Reagents for Karl Fischer Titration, from
Riedel-deHaen (www.rdhlab.de) or Sigma Aldrich (www.sigma-aldrich.com) and Moisture Measurement by Karl Fischer Titrimetry, 2nd ed., by GFS
Chemicals, Inc., January 2004.
7.3.1 Generator Titrant Solution (catholyte), containing iodine, sulfur dioxide, pyridine or other organic base and methanol or
other alcohol to provide iodine in the reaction mixture.
7.3.2 Solvent Titration Solution (anolyte), prepared as per instrument specifications.
7.3.3 Neutralizing Solution, methanol containing approximately 20 mg H O/mL.
8. Safety Precautions
8.1 The reagents contain one or more of the following: iodine, pyridine or other organic base, sulfur dioxide, and methanol or other
alcohol. Wear chemical resistant gloves when mixing the reagents and removing solution from the titration chamber. Care must
be exercised to avoid inhalation of reagent vapors, or direct contact of the reagent with the skin.
9. Sampling
9.1 Because of the low concentration of water to be measured, maximum care must be exercised at all times to avoid
contaminating the sample with moisture from the sample container, the atmosphere, or transfer equipment.
ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference Materials, 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. ®
Hydranal is a registered trademark of Sigma-Aldrich, Inc, St. Louis, MO.
E1064 − 24
9.1.1 Dry the sample bottles and caps overnight in an oven at 100 °C before using. Allow to cool in a desiccator before filling and
sealing.
9.1.2 Fill the sample bottle as rapidly as possible to within 25 mm of the top and immediately seal.
9.2 Remove the test specimens for analysis from the sample bottle with a dry hypodermic syringe. Inject dry nitrogen into the
sample bottle with the syringe to displace the sample that is removed.
10. Preparation of Apparatus
10.1 Clean, dry, and assemble the titration chamber as directed in the manufacturer’s instructions. Use fluorocarbon grease or
TFE-fluorocarbon to seal the upper and lower sections of the chamber from atmospheric moisture. Connect the leads from the
sensing and generator electrodes to the titrator.
10.2 Prepare the titration solution (7.3.2) as directed by the instrument manufacturer and fill the instrument reservoir as directed
by the manufacturer.
10.3 Add the generator solution (7.3.1) to the generator assembly and replace the cover cap. The surface of the generator solution
must be below the level of the titration solution to prevent backflow contamination of the titration solution. The generator solution
may have to be removed periodically to maintain the lower level.
10.4 Follow the manufacturer’s procedure to dry the titration cell.
11. Verification of Calibration
11.1 Different autotitrators may vary in calibration procedures. Consult the operating manual for the autotitrator in use. Stable,
prepackaged Quality Control (QC) water standards are commercially available with 10 mg/kg. 100 mg/kg and 1 % (m/m) water
content for this purpose. It is desirable to verify calibration with a standard solution that approximates the same range of water
expected to be in the samples. If the measured value exceeds 65 % of the known amount, take appropriate action before
proceeding with the sample test.
NOTE 3—This may require replacing or regenerating the reagent solutions.
12. Procedure
...