ASTM E2679-22

Standard Test Method for Acidity in Mono-, Di-, Tri- and Tetraethylene Glycol by <brk />Non-Aqueous Potentiometric Titration

SIGNIFICANCE AND USE
5.1 This test method provides for the quantitative determination of total acidity in ethylene glycols by non-aqueous potentiometric titration. The run time for titration of ethylene glycol samples ranges from 5 to 10 min with no sample preparation required. The length of time for a titration depends on the amount of acidity in the sample and the acidity generally increases from monoethylene glycol to the higher glycols like tetraethylene glycol.  
5.2 Acceptable levels of acidity in ethylene glycols vary with the manufacturer’s specifications but are normally below 200 mg/kg. Knowledge of the acidity in ethylene glycols is required to establish whether the product quality meets specification requirements.
SCOPE
1.1 This test method covers the determination of total acidity as acetic acid in commonly available grades of monoethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol using a non-aqueous potentiometric titration. This test method is useful for determining low levels of acidity, below 200 mg/kg.  
1.2 The mono-, di-, tri- and tetraethylene glycols can be analyzed directly by this test method without any sample preparation.  
1.3 Review the current appropriate Safety Data Sheets (SDS) for detailed information concerning toxicity, first aid procedures, and safety precautions.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific hazards statements are given in the section on Hazards, Section 9.  
1.6 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: 30-Jun-2022
• ICS: 71.080.60 - Alcohols. Ethers
• Technical Committee: D16 - Aromatic, Industrial, Specialty and Related Chemicals
• Drafting Committee: D16.14 - Alcohols & Glycols

Relations

• Refers: ASTM D6809-02(2016) - Standard Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials
• Effective Date: 01-Nov-2016
• Refers: ASTM D6809-02(2007) - Standard Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials
• Effective Date: 01-Jun-2007
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D6809-02 - Standard Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials
• Effective Date: 10-Jun-2002
• 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

Overview

ASTM E2679-22 specifies the standard test method for determining total acidity as acetic acid in monoethylene glycol (MEG), diethylene glycol (DEG), triethylene glycol (TEG), and tetraethylene glycol (TTEG) using non-aqueous potentiometric titration. This test method delivers a quantitative assessment of acidity in commonly available grades of ethylene glycols, providing direct analysis without any sample preparation. The procedure is efficient, with a typical titration time of 5 to 10 minutes per sample. Monitoring acidity is crucial for evaluating product quality and compliance with manufacturer specifications, especially since acceptable acidity levels in ethylene glycols are generally below 200 mg/kg.

Key Topics

• Purpose and Scope: The standard focuses on rapid, direct measurement of low levels of acidity (as acetic acid) in mono-, di-, tri-, and tetraethylene glycols.
• Analytical Method: Utilizes non-aqueous potentiometric titration, where a sample is titrated with a standardized aqueous base (potassium hydroxide or sodium hydroxide).
• Direct Sample Analysis: Ethylene glycols can be titrated directly-no dilution or pre-treatment is needed before analysis.
• Precision and Quality Control: Includes requirements for calibration and standardization of titrants and electrodes, as well as recommendations for ongoing quality control to ensure reliable test results.
• Health and Safety: Emphasizes reviewing Safety Data Sheets (SDS) and following laboratory best practices for handling chemicals and reagents.
• Data Reporting: Results are reported as mg/kg of acetic acid, with attention to precision and accuracy requirements.

Applications

• Quality Control in Glycol Production: Used by manufacturers and laboratories to ensure ethylene glycols meet required acidity specifications for industrial use, such as antifreeze formulations, deicing operations, and as precursors in chemical manufacturing.
• Specification Compliance: Verifies that products adhere to manufacturer and industry standards regarding acidity, which affects the performance and stability of glycols in end-use applications.
• Process Monitoring: Enables producers to monitor and adjust production parameters to maintain product quality and minimize risks associated with excessive acidity.
• Interlaboratory Comparisons: Supports consistency in test results across different facilities, which is essential for supplier and customer confidence.
• Research and Product Development: Serves as a reliable method for testing new grades of ethylene glycols or evaluating the effect of processing changes on product acidity.

Related Standards

• ASTM D1193 - Specification for Reagent Water: Defines water quality for laboratory reagents used in the test method.
• ASTM D6809 - Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials: Offers QA/QC practices relevant to chemical testing.
• ASTM E180 - Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Specialty Chemicals (Withdrawn): Historical context for development of precision statements.
• International Principles: Developed in accordance with WTO TBT Committee principles for the development of international standards.

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Keywords: ASTM E2679-22, acidity in ethylene glycol, non-aqueous potentiometric titration, monoethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, quality control, chemical analysis, acetic acid, industrial standards

By adhering to ASTM E2679-22, laboratories and manufacturers gain a validated, efficient approach to acidity testing in glycols-ensuring product quality and compliance with industry demands.

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: E2679 − 22
Standard Test Method for
Acidity in Mono-, Di-, Tri- and Tetraethylene Glycol by
Non-Aqueous Potentiometric Titration
This standard is issued under the fixed designation E2679; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers the determination of total
D1193Specification for Reagent Water
acidity as acetic acid in commonly available grades of mono-
D6809Guide for Quality Control and Quality Assurance
ethylene glycol, diethylene glycol, triethylene glycol and
Procedures for Aromatic Hydrocarbons and Related Ma-
tetraethylene glycol using a non-aqueous potentiometric titra-
terials
tion. This test method is useful for determining low levels of
E180Practice for Determining the Precision of ASTM
acidity, below 200 mg/kg.
Methods for Analysis and Testing of Industrial and Spe-
1.2 The mono-, di-, tri- and tetraethylene glycols can be
cialty Chemicals (Withdrawn 2009)
analyzed directly by this test method without any sample
3. Terminology
preparation.
3.1 Definitions:
1.3 Review the current appropriate Safety Data Sheets
3.1.1 acidity—the amount of total acid titrated with an
(SDS) for detailed information concerning toxicity, first aid
aqueous base (KOH or NaOH) in a sample of ethylene glycol.
procedures, and safety precautions.
The acidity is calculated as acetic acid in mg/kg.
1.4 The values stated in SI units are to be regarded as
4. Summary of Test Method
standard. No other units of measurement are included in this
standard. 4.1 An aliquot of a mono-, di-, tri- or tetraethylene glycol
sample is weighed and titrated potentiometrically with a
1.5 This standard does not purport to address all of the
monotonic or dynamic mode of titrant addition using an
safety concerns, if any, associated with its use. It is the
aqueous base (NaOH or KOH) solution to determine the acid
responsibility of the user of this standard to establish appro-
content in milligrams of acid as acetic acid per kilogram of
priate safety, health, and environmental practices and deter-
sample.Anethyleneglycolsamplecanbeanalyzeddirectlyby
mine the applicability of regulatory limitations prior to use.
this test method without any sample preparation using a
Specific hazards statements are given in the section on
combination pH electrode with an inert ethanol electrolyte
Hazards, Section 9.
designed for non-aqueous titrations. The potentiometric titra-
1.6 This international standard was developed in accor-
tion readings in millivolts are plotted automatically against the
dance with internationally recognized principles on standard-
respectivevolumesofthetitratingsolutionandtheendpointis
ization established in the Decision on Principles for the
identified by a well-defined inflection in the resulting curve.
Development of International Standards, Guides and Recom-
5. Significance and Use
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
5.1 This test method provides for the quantitative determi-
nation of total acidity in ethylene glycols by non-aqueous
potentiometric titration. The run time for titration of ethylene
glycol samples ranges from 5 to 10 min with no sample
preparationrequired.Thelengthoftimeforatitrationdepends
1 2
This test method is under the jurisdiction of ASTM Committee D16 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Aromatic, Industrial, Specialty and Related Chemicals and is the direct responsi- contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
bility of Subcommittee D16.14 on Alcohols & Glycols. Standards volume information, refer to the standard’s Document Summary page on
CurrenteditionapprovedJuly1,2022.PublishedJuly2022.Originallyapproved the ASTM website.
ɛ1 3
in 2009. Last previous edition approved in 2016 as E2679– 09 (2016) . DOI: The last approved version of this historical standard is referenced on
10.1520/E2679-22. 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
E2679 − 22
ontheamountofacidityinthesampleandtheaciditygenerally betterresponsethanadualelectrodesystem.Theyshouldhave
increases from monoethylene glycol to the higher glycols like a movable sleeve for easy rinsing and addition of electrolyte.
tetraethylene glycol.
7.3 Titration Beaker, borosilicate glass or plastic beaker of
5.2 Acceptable levels of acidity in ethylene glycols vary suitable size for the titration.
with the manufacturer’s specifications but are normally below
7.4 Stirrer, variable-speed mechanical stirrer, a suitable
200 mg/kg. Knowledge of the acidity in ethylene glycols is
type,equippedwithapropeller-typestirringpaddle.Therateof
required to establish whether the product quality meets speci-
stirringshallbesufficienttoproducevigorousagitationwithout
fication requirements.
spatteringandwithoutstirringairintothesolution.Apropeller
with blades 6 mm in radius and set at a pitch of 30 to 45° is
6. Interferences
satisfactory. A magnetic stirrer and stirring bars is also satis-
6.1 Aqueousbasesolutions,suchasthe0.01mol/LKOHor
factory.
NaOH titrant, may absorb carbon dioxide from the air to
7.4.1 If an electrical stirring apparatus is used, it shall be
produce carbonate ions in the titrant and change the concen-
electrically correct and grounded so that connecting or discon-
tration of the titrant. Care should be taken to minimize
necting the power to the motor will not produce a permanent
exposure of basic titrants to the air.Verify the concentration of
change in the instrument reading during the course of the
the titrant (standardize the titrant) if prolonged exposure to the
titration.
air occurs.
6.2 Minimizeexposureoftheethyleneglycolsamplestothe 8. Reagents and Materials
air to avoid contamination.
8.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
7. Apparatus
all reagents shall conform to the specifications of the commit-
7.1 Potentiometric Titrator—Automatic titration systems
tee onAnalytical Reagents of theAmerican Chemical Society,
capable of adding fixed increments of titrant at fixed time 4
where such specifications are available. Other grades may be
intervals (monotonic) or variable titrant increments with elec-
used, provided it is first ascertained that the reagent is of
trode stability between increment additions (dynamic) with
sufficiently high purity to permit its use without lessening the
endpointseekingcapabilitiesasprescribedinthemethod.Asa
accuracy of the determination.
minimum, the automatic titration system shall meet the perfor-
8.1.1 Commercially available solutions may be used in
mance and specification requirements as warranted by the
place of laboratory preparations provided the solutions have
manufacturer.
been certified as being equivalent.
7.1.1 Amonotonicordynamicmodeoftitrantadditionshall
8.1.2 Alternate volumes of the solutions may be prepared,
be used. During the titration, the speed and volume of the
provided the final solution concentration is equivalent.
addition may vary depending on the rate of change of the
8.1.3 Purity of Water—Unless otherwise indicated, refer-
system. The recommended minimum volume increment is
ence to water shall be understood to mean reagent water that
0.02mL for low acidity samples such as polyester grade
meets the requirements of either Type I or II of Specification
monoethylene glycol and the recommended maximum volume
D1193.
increment is 0.05 mL. A signal drift of 10 mV/min and
8.1.4 50 % Potassium Hydroxide, carbonate free
endpoint recognition set to greatest is also recommended to
(Warning—Causes severe burns.)
ensure endpoint detection. When using a monotonic titrant
8.1.5 50 % Sodium Hydroxide, carbonate free (Warning—
additionthewaitingtimebetweenincrementadditionsneedsto
Causes severe burns.)
be sufficient to allow for mixing and electrode response. It is
8.1.6 Potassium Hydrogen Phthalate (KHP) Solution—Dry
recommended to wait at least 10 s between additions.
4to5gofKHPat110°Cinan oven for 2 h.Allow the dried
7.1.2 Buret, 5 mL capacity, capable of delivering titrant in
KHP to cool to room temperature in a desiccator before
0.02 mL or larger increments. The buret tip should be able to
weighing.Weighapproximately1.0gofdriedKHPandrecord
delivertitrantdirectlyintothetitrationvesselwithoutexposure
the weight to the nearest 60.0001 g and make up to the mark
to the surrounding air. It is recommended that the buret used
with water in a 500 mL Class A volumetric flask. Mix
foraqueousbasesolutionsshouldhaveaguardtubecontaining
thoroughly to dissolve the KHP. Express the concentration of
a carbon dioxide absorbing substance.
KHP in solution as Molarity in moles of KHP per liter of
7.1.3 Titration Stand, suitable for supporting the electrode,
solution (see 13.1). The use of a volumetric flask can be
stirrer and buret tip.
avoided by weighing 1.0 g of dried KHP to the nearest
7.2 Combination pH Electrodes—Sensing electrodes may
0.0001g into a beaker and adding 500 g of water. Mix
have the Ag/AgCl reference electrode built into the same
thoroughly to dissolve the KHP. Record the total weight of
electrode body, which offers the convenience of working with
and maintaining only one electrode. A combination pH elec-
trodedesignedfornon-aqueoustitrationsoforganicsolventsis
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Standard-Grade Reference Materials, American Chemical Society, Washington,
needed for titration of glycols. The combination pH electrode
DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
should have a sleeve junction on the reference compartment
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
and should use an inert ethanol electrolyte, 1–3 mol/L LiCl in
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
ethanol. Combination pH electrodes should have the same or copeial Convention, Inc. (USPC), Rockville, MD.
E2679 − 22
water and KHP to the nearest 60.01 g and express the electrolytefromtheelectrode(vacuumsuction),washawayall
concentration of KHP in the solution as mg KHP per gram of the salt (if present) with water and then rinse with ethanol.
solution (see 13.1). The KHP solution should be made fresh Rinse several times with the LiCl electrolyte solution and fill
before use. the reference compartment with the LiCl/ethanol electrolyte.
8.1.7 Commercial Aqueous pH 4 and pH 7 Buffer
10.3 Maintenance and Storage of Electrodes:
Solutions—These solutions shall be replaced at regular inter-
10.3.1 Follow the manufacturer’s instructions for storage
vals consistent with their stability or when contamination is
and use of the electrode.
suspected. Information relating to their stability should be
10.3.2 Prior to each titration soak the prepared electrode in
obtained from the manufacturer.
water for at least 2 min. Rinse the electrode with deionized
8.1.8 Potassium Hydroxide (KOH) 0.01 mol/L—Weigh
waterimmediatelybeforeuse.Theglassmembraneneedstobe
1.122 6 0.02 g of 50% KOH into a one liter volumetric flask
rehydrated after titration of glycol (non-aqueous) material.
that contains about 200 mLof water that has been degassed to
10.3.3 When not in use, immerse the lower half of the
remove dissolved CO . Dilute to the one-liter mark with
combination electrode in LiCl electrolyte. Do not allow elec-
additional deionized water. The KOH solution should be
trodes to remain immersed in a titrated sample for any
standardizedusingtheKHPsolutiontodeterminethetiter.The
appreciable period of time between titrations. While the
titranttitershouldbecheckedperiodicallyduetoabsorptionof
electrodes are not extremely fragile, handle them carefully at
carbon dioxide with use over time. A titrant of sodium
all times.
hydroxide, 0.01 mol/LNaOH, made from 50% NaOH may be
substituted for KOH.
11. Calibration and Standardization
8.1.9 Lithium Chloride Electrolyte—Prepare a 1–3 mol/L
solution of lithium chloride (LiCl) in ethanol per the electrode
11.1 Calibration of Electrode:
manufacturer’s recommendation.
11.1.1 Select the correct electrode for the analysis (see7.2).
9. Hazards
11.1.2 Verifythattheelectrodeisfilledwith1–3mol/LLiCl
in ethanol solution (see 7.2).
9.1 Each analyst must be acquainted with the potential
11.1.3 Prepare the two buffer solutions, pH 7.0 and pH 4.0
hazards of the equipment, reagents, products, solvents and
by placing approximately 50 mLof each solution in individual
procedures before beginning laboratory work. Sources of
125-mL dis
...

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: E2679 − 09 (Reapproved 2016) E2679 − 22
Standard Test Method for
Acidity in Mono-, Di-, Tri- and Tetraethylene Glycol by
Non-Aqueous Potentiometric Titration
This standard is issued under the fixed designation E2679; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Minor editorial changes were made in February 2016.
1. Scope Scope*
1.1 This test method covers the determination of total acidity as acetic acid in commonly available grades of monoethylene glycol,
diethylene glycol, triethylene glycol and tetraethylene glycol using a non-aqueous potentiometric titration. This test method is
useful for determining low levels of acidity, below 200 mg/kg.
1.2 The mono-, di-, tri- and tetraethylene glycols can be analyzed directly by this test method without any sample preparation.
1.3 Review the current appropriate Safety Data Sheets (SDS) for detailed information concerning toxicity, first aid procedures, and
safety precautions.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. Specific hazards statements are given in the section on Hazards, Section 9.
1.6 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
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)
3. Terminology
3.1 Definitions:
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 D16.14 on Alcohols & Glycols.
Current edition approved Jan. 1, 2016July 1, 2022. Published February 2016July 2022. Originally approved in 2009. Last previous edition approved in 20092016 as
ɛ1
E2679 – 09. 09 (2016) . DOI: 10.1520/E2679-09R16E01.10.1520/E2679-22.
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
E2679 − 22
3.1.1 acidity—the amount of total acid titrated with an aqueous base (KOH or NaOH) in a sample of ethylene glycol. The acidity
is calculated as acetic acid in mg/kg.
4. Summary of Test Method
4.1 An aliquot of a mono-, di-, tri- or tetraethylene glycol sample is weighed and titrated potentiometrically with a monotonic or
dynamic mode of titrant addition using an aqueous base (NaOH or KOH) solution to determine the acid content in milligrams of
acid as acetic acid per kilogram of sample. An ethylene glycol sample can be analyzed directly by this test method without any
sample preparation using a combination pH electrode with an inert ethanol electrolyte designed for non-aqueous titrations. The
potentiometric titration readings in millivolts are plotted automatically against the respective volumes of the titrating solution and
the end point is identified by a well-defined inflection in the resulting curve.
5. Significance and Use
5.1 This test method provides for the quantitative determination of total acidity in ethylene glycols by non-aqueous potentiometric
titration. The run time for titration of ethylene glycol samples ranges from 5 to 10 min with no sample preparation required. The
length of time for a titration depends on the amount of acidity in the sample and the acidity generally increases from monoethylene
glycol to the higher glycols like tetraethylene glycol.
5.2 Acceptable levels of acidity in ethylene glycols vary with the manufacturer’s specifications but are normally below 200 mg/kg.
Knowledge of the acidity in ethylene glycols is required to establish whether the product quality meets specification requirements.
6. Interferences
6.1 Aqueous base solutions, such as the 0.01 mol/L KOH or NaOH titrant, may absorb carbon dioxide from the air to produce
carbonate ions in the titrant and change the concentration of the titrant. Care should be taken to minimize exposure of basic titrants
to the air. Verify the concentration of the titrant (standardize the titrant) if prolonged exposure to the air occurs.
6.2 Minimize exposure of the ethylene glycol samples to the air to avoid contamination.
7. Apparatus
7.1 Potentiometric Titrator—Automatic titration systems capable of adding fixed increments of titrant at fixed time intervals
(monotonic) or variable titrant increments with electrode stability between increment additions (dynamic) with endpoint seeking
capabilities as prescribed in the method. As a minimum, the automatic titration system shall meet the performance and specification
requirements as warranted by the manufacturer.
7.1.1 A monotonic or dynamic mode of titrant addition shall be used. During the titration, the speed and volume of the addition
may vary depending on the rate of change of the system. The recommended minimum volume increment is 0.02 mL for low acidity
samples such as polyester grade monoethylene glycol and the recommended maximum volume increment is 0.05 mL. A signal drift
of 10 mV/min and endpoint recognition set to greatest is also recommended to ensure endpoint detection. When using a monotonic
titrant addition the waiting time between increment additions needs to be sufficient to allow for mixing and electrode response. It
is recommended to wait at least 10 s between additions.
7.1.2 Buret, 5 mL capacity, capable of delivering titrant in 0.02 mL or larger increments. The buret tip should be able to deliver
titrant directly into the titration vessel without exposure to the surrounding air. It is recommended that the buret used for aqueous
base solutions should have a guard tube containing a carbon dioxide absorbing substance.
7.1.3 Titration Stand, suitable for supporting the electrode, stirrer and buret tip.
7.2 Combination pH Electrodes—Sensing electrodes may have the Ag/AgCl reference electrode built into the same electrode body,
which offers the convenience of working with and maintaining only one electrode. A combination pH electrode designed for
non-aqueous titrations of organic solvents is needed for titration of glycols. The combination pH electrode should have a sleeve
junction on the reference compartment and should use an inert ethanol electrolyte, 1–3 mol/L LiCl in ethanol. Combination pH
electrodes should have the same or better response than a dual electrode system. They should have a movable sleeve for easy
rinsing and addition of electrolyte.
E2679 − 22
7.3 Titration Beaker, borosilicate glass or plastic beaker of suitable size for the titration.
7.4 Stirrer, variable-speed mechanical stirrer, a suitable type, equipped with a propeller-type stirring paddle. The rate of stirring
shall be sufficient to produce vigorous agitation without spattering and without stirring air into the solution. A propeller with blades
6 mm in radius and set at a pitch of 30 to 45° is satisfactory. A magnetic stirrer and stirring bars is also satisfactory.
7.4.1 If an electrical stirring apparatus is used, it shall be electrically correct and grounded so that connecting or disconnecting
the power to the motor will not produce a permanent change in the instrument reading during the course of the titration.
8. Reagents and Materials
8.1 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.
8.1.1 Commercially available solutions may be used in place of laboratory preparations provided the solutions have been certified
as being equivalent.
8.1.2 Alternate volumes of the solutions may be prepared, provided the final solution concentration is equivalent.
8.1.3 Purity of Water—Unless otherwise indicated, reference to water shall be understood to mean reagent water that meets the
requirements of either Type III or IIIII of Specification D1193.
8.1.4 50 % Potassium Hydroxide, carbonate free (Warning—Causes severe burns.)
8.1.5 50 % Sodium Hydroxide, carbonate free (Warning—Causes severe burns.)
8.1.6 Potassium Hydrogen Phthalate (KHP) Solution—Dry 4 to 5 g of KHP at 110ºC110 °C in an oven for 2 h. Allow the dried
KHP to cool to room temperature in a desiccator before weighing. Weigh approximately 1.0 g of dried KHP and record the weight
to the nearest 60.0001 g and make up to the mark with DI Type II water in a 500 mL Class A volumetric flask. Mix thoroughly
to dissolve the KHP. Express the concentration of KHP in solution as Molarity in moles of KHP per liter of solution (see 13.1).
The use of a volumetric flask can be avoided by weighing 1.0 g of dried KHP to the nearest 0.0001 g into a beaker and adding
500 g of DI Type II water. Mix thoroughly to dissolve the KHP. Record the total weight of water and KHP to the nearest 60.01
g and express the concentration of KHP in the solution as mg KHP per gram of solution (see 13.1). The KHP solution should be
made fresh before use.
8.1.7 Commercial Aqueous pH 4 and pH 7 Buffer Solutions—These solutions shall be replaced at regular intervals consistent with
their stability or when contamination is suspected. Information relating to their stability should be obtained from the manufacturer.
8.1.8 Potassium Hydroxide (KOH) 0.01 mol/L—Weigh 1.122 6 0.02 g of 50 % KOH into a one liter volumetric flask that contains
about 200 mL of Type II deionized water that has been degassed to remove dissolved CO . Dilute to the one-liter mark with
additional deionized water. The KOH solution should be standardized using the KHP solution to determine the titer. The titrant titer
should be checked periodically due to absorption of carbon dioxide with use over time. A titrant of sodium hydroxide, 0.01 mol/L
NaOH, made from 50 % NaOH may be substituted for KOH.
8.1.9 Lithium Chloride Electrolyte—Prepare a 1–3 mol/L solution of lithium chloride (LiCl) in ethanol per the electrode
manufacturer’s recommendation.
9. Hazards
9.1 Each analyst must be acquainted with the potential hazards of the equipment, reagents, products, solvents and procedures
Reagent Chemicals, American Chemical Society Specifications,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. (USP),(USPC),
Rockville, MD.
E2679 − 22
before beginning laboratory work. Sources of information include: operation manuals, SDS, literature, and other related data.
Safety information should be requested from the supplier. Disposal of waste materials, reagents, reactants, and solvents must be
in compliance with laws and regulations from all applicable governmental agencies.
9.2 Ethylene glycol products are intended for industrial use only. Before handling or using these products, read the current SDS
for each product (see 9.1).
9.3 The following hazards are associated with the application of this test method and the use of an automatic titrator.
9.3.1 Chemical Hazard:
9.3.1.1 A solution of 50 % potassium hydroxide or sodium hydroxide is corrosive and should be handled in a fume hood with
rubber gloves, chemical goggles, and lab coat or chemical-resistant apron. Always add the base to water when diluting 50 % KOH
or NaOH.
9.3.1.2 Ethanol is a flammable and toxic solvent that is used to prepare the lithium chloride electrolyte solution for the combination
electrode. Be careful when handling a flammable solvent and work in a well-ventilated area away from sources of ignition.
10. Preparation of Apparatus
10.1 Prepare the titrator in accordance with the manufacturer’s instructions. Care should be taken to see that there are no air
bubbles in the buret tip which might be dispensed during the titration and can lead to errors.
10.2 Preparation of Electrodes:
10.2.1 When the combination pH electrode contains a Ag/AgCl reference with an electrolyte which is not 1–3 mol/L LiCl in
ethanol, the electrolyte must be replaced. Drain the electrolyte from the electrode (vacuum suction), wash away all the salt (if
present) with water and then rinse with ethanol. Rinse several times with the LiCl electrolyte solution and fill the reference
compartment with the LiCl/ethanol electrolyte.
10.3 Maintenance and Storage of Electrodes:
10.3.1 Follow the manufacturer’s instructions for storage and use of the electrode.
10.3.2 Prior to each titration soak the prepared electrode in water for at least 2 min. Rinse the electrode with deionized water
immediately before use. The glass membrane needs to be rehydrated after titration of glycol (non-aqueous) material.
10.3.3 When not in use, immerse the
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