ASTM E2679-09(2016)e1

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 and health practices and determine the applicability of regulatory limitations prior to use. Specific hazards statements are given in the section on Hazards, Section 9.

General Information

• Status: Historical
• Publication Date: 31-Dec-2015
• ICS: 71.080.60 - Alcohols. Ethers
• Technical Committee: D16 - Aromatic, Industrial, Specialty and Related Chemicals
• Drafting Committee: D16.14 - Alcohols & Glycols

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
´1
Designation: E2679 − 09 (Reapproved 2016)
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.
ε NOTE—Minor editorial changes were made in February 2016.
1. Scope 2. Referenced Documents
1.1 This test method covers the determination of total 2.1 ASTM Standards:
acidity as acetic acid in commonly available grades of mono- D1193Specification for Reagent Water
ethylene glycol, diethylene glycol, triethylene glycol and E180Practice for Determining the Precision of ASTM
tetraethylene glycol using a non-aqueous potentiometric titra- Methods for Analysis and Testing of Industrial and Spe-
tion. This test method is useful for determining low levels of cialty Chemicals (Withdrawn 2009)
acidity, below 200 mg/kg.
3. Terminology
1.2 The mono-, di-, tri- and tetraethylene glycols can be
3.1 Definitions:
analyzed directly by this test method without any sample
3.1.1 acidity—the amount of total acid titrated with an
preparation.
aqueous base (KOH or NaOH) in a sample of ethylene glycol.
1.3 Review the current appropriate Safety Data Sheets
The acidity is calculated as acetic acid in mg/kg.
(SDS) for detailed information concerning toxicity, first aid
4. Summary of Test Method
procedures, and safety precautions.
4.1 An aliquot of a mono-, di-, tri- or tetraethylene glycol
1.4 The values stated in SI units are to be regarded as
sample is weighed and titrated potentiometrically with a
standard. No other units of measurement are included in this
monotonic or dynamic mode of titrant addition using an
standard.
aqueous base (NaOH or KOH) solution to determine the acid
1.5 This standard does not purport to address all of the
content in milligrams of acid as acetic acid per kilogram of
safety concerns, if any, associated with its use. It is the
sample.Anethyleneglycolsamplecanbeanalyzeddirectlyby
responsibility of the user of this standard to establish appro-
this test method without any sample preparation using a
priate safety, health, and environmental practices and deter-
combination pH electrode with an inert ethanol electrolyte
mine the applicability of regulatory limitations prior to use.
designed for non-aqueous titrations. The potentiometric titra-
Specific hazards statements are given in the section on
tion readings in millivolts are plotted automatically against the
Hazards, Section 9.
respectivevolumesofthetitratingsolutionandtheendpointis
1.6 This international standard was developed in accor-
identified by a well-defined inflection in the resulting curve.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
5. Significance and Use
Development of International Standards, Guides and Recom-
5.1 This test method provides for the quantitative determi-
mendations issued by the World Trade Organization Technical
nation of total acidity in ethylene glycols by non-aqueous
Barriers to Trade (TBT) Committee.
potentiometric titration. The run time for titration of ethylene
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
Current edition approved Jan. 1, 2016. Published February 2016. Originally the ASTM website.
approved in 2009. Last previous edition approved in 2009 as E2679– 09. DOI: The last approved version of this historical standard is referenced on
10.1520/E2679-09R16E01. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
E2679 − 09 (2016)
glycol samples ranges from 5 to 10 min with no sample and should use an inert ethanol electrolyte, 1–3 mol/L LiCl in
preparationrequired.Thelengthoftimeforatitrationdepends ethanol. Combination pH electrodes should have the same or
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 eitherType II or III 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.
4to5gofKHPat110ºC in an 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 DI Type II water in a 500 mL Class A volumetric flask.
foraqueousbasesolutionsshouldhaveaguardtubecontaining
MixthoroughlytodissolvetheKHP.Expresstheconcentration
a carbon dioxide absorbing substance.
of 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
have the Ag/AgCl reference electrode built into the same
electrode body, which offers the convenience of working with
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
and maintaining only one electrode. A combination pH elec-
listed by the American Chemical Society, see Analar Standards for Laboratory
trodedesignedfornon-aqueoustitrationsoforganicsolventsis
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
needed for titration of glycols. The combination pH electrode
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USP), Rockville,
should have a sleeve junction on the reference compartment MD.
´1
E2679 − 09 (2016)
0.0001g into a beaker and adding 500 g of DI Type II water. 10.2.1 When the combination pH electrode contains a
MixthoroughlytodissolvetheKHP.Recordthetotalweightof Ag/AgCl reference with an electrolyte which is not 1–3 mol/L
water and KHP to the nearest 60.01 g and express the LiCl in ethanol, the electrolyte must be replaced. Drain the
concentration of KHP in the solution as mg KHP per gram of electrolytefromtheelectrode(vacuumsuction),washawayall
solution (see 13.1). The KHP solution should be made fresh the salt (if present) with water and then rinse with ethanol.
before use. Rinse several times with the LiCl electrolyte solution and fill
8.1.7 Commercial Aqueous pH 4 and pH 7 Buffer the reference compartment with the LiCl/ethanol electrolyte.
Solutions—These solutions shall be replaced at regular inter-
10.3 Maintenance and Storage of Electrodes:
vals consistent with their stability or when contamination is
10.3.1 Follow the manufacturer’s instructions for storage
suspected. Information relating to their stability should be
and use of the electrode.
obtained from the manufacturer.
10.3.2 Prior to each titration soak the prepared electrode in
8.1.8 Potassium Hydroxide (KOH) 0.01 mol/L—Weigh
water for at least 2 min. Rinse the electrode with deionized
1.122 6 0.02 g of 50% KOH into a one liter volumetric flask
waterimmediatelybeforeuse.Theglassmembraneneedstobe
thatcontainsabout200mLofTypeIIdeionizedwaterthathas
rehydrated after titration of glycol (non-aqueous) material.
beendegassedtoremovedissolvedCO .Dilutetotheone-liter
10.3.3 When not in use, immerse the lower half of the
mark with additional deionized water. The KOH solution
combination electrode in LiCl electrolyte. Do not allow elec-
should be standardized using the KHP solution to determine
trodes to remain immersed in a titrated sample for any
the titer.The titrant titer should be checked periodically due to
appreciable period of time between titrations. While the
absorption of carbon dioxide with use over time. A titrant of
electrodes are not extremely fragile, handle them carefully at
sodium hydroxide, 0.01 mol/LNaOH, made from 50% NaOH
all times.
may be substituted for KOH.
8.1.9 Lithium Chloride Electrolyte—Prepare a 1–3 mol/L
11. Calibration and Standardization
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 (see 7.2).
11.1.2 Verifythattheelectrodeisfilledwith1–3mol/LLiCl
9. Hazards
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 disposable beakers.
information include: operation manuals, SDS, literature, and
11.1.4 Calibrate the electrode using the two buffer solutions
otherrelateddata.Safetyinformationshouldberequestedfrom
according to the manufacturer’s instructions. Immerse the
the supplier. Disposal of waste materials, reagents, reactants,
electrode in each buffer solution, adjust the stirring speed so
and solvents must be in compliance with laws and regulations
adequate mixing occurs without forming a vortex and wait for
from all applicable governmental agencies.
theinstrumentreading.Whenthereadingiscomplete,rinsethe
electrode in high purity water, wipe gently and repeat with the
9.2 Ethylene glycol products are intended for industrial use
other buffer solution. Record the pH value with an accuracy of
only. Before handling or using these products, read the current
0.01 and the temperature with an accuracy of 0.1°C. The
SDS for each product (see 9.1).
measured pH values should be within 60.05 pH units of the
9.3 The following hazards are associated with the applica-
buffer’s certified value.
tion of this test method and the use of an automatic titrator.
11.1.5 Verify that the calibration slope is between 0.95 and
9.3.1 Chemical Hazard:
1.02.AnidealpHglasselectrodehasaslopeof1.00(100%of
9.3.1.1 A solution of 50% potassium hydroxide or sodium
the Nernst slope) and an electrode zero point of 0 mV for pH
hydroxide is corrosive and should be handled in a fume hood
7 at 25ºC. In practice, the electrode zero point potential should
with gloves, chemical goggles, and lab coat or chemical-
be within 615 mV(corresponding to pH 6.75 to 7.25) and the
resistant apron. Always add the
...

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 E2679 − 09 (Reapproved 2016)
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
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 Material Safety Data Sheets (MSDS)(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 and health practices and determine the applicability of regulatory
limitations prior to use. Specific hazards statements are given in the section on Hazards, Section 9.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
This test method is under the jurisdiction of ASTM Committee E15 on Industrial and Specialty Chemicals and is the direct responsibility of Subcommittee E15.02 on
Product Standards.
Current edition approved April 1, 2009Jan. 1, 2016. Published May 2009February 2016. Originally approved in 2009. Last previous edition approved in 2009 as E2679-09.
DOI: 10.1520/E2679-09.10.1520/E2679-09R16E01.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
E2679 − 09 (2016)
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:
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 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.
7.3 Titration Beaker, borosilicate glass or plastic beaker of suitable size for the titration.
The last approved version of this historical standard is referenced on www.astm.org.
´1
E2679 − 09 (2016)
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 II or III 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 110ºC 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 6 0.0001 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 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
before beginning laboratory work. Sources of information include: operation manuals, MSDS,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
MSDSSDS 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
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.
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),(USP), Rockville, MD.
´1
E2679 − 09 (2016)
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 lower half of the combination electrode in LiCl electrolyte. Do not allow electrodes to
remain immersed in a titrated sample for any appreciable period of time between titrations. While the electrodes are not extremely
fragile, handle them carefully at all times.
11. Calibration and Standardization
11.1 Calibration of Electrode:
11.1.1 Select the correct electrode for the analysis (see 7.2).
11.1.2 Verify that the electrode is filled with 1–3 mol/L LiCl in ethanol solution (see 7.2).
11.1.3 Prepare the two buffer solutions, pH 7.0 and pH 4.0 by placing approximately 50 mL of each solution in individual
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