ASTM D7922-23

Standard Test Method for Determination of Glycol for In-Service Engine Oils by Gas Chromatography

SIGNIFICANCE AND USE
5.1 Some glycol/antifreeze dilution of in-service engine oil is normal under typical operating conditions. However, excessive glycol dilution can lead to decreased performance, premature wear, or sudden engine failure. This test method provides a means of quantifying the level of glycol based antifreeze dilution, allowing the user to take necessary action.
SCOPE
1.1 This test method covers the determination of glycol based antifreeze for in-service engine oil by derivative headspace/gas chromatography.  
1.2 Sample is derivatized in-situ directly in a headspace sampling vial prior to vapor phase extraction and injection into a gas chromatograph.  
1.3 The chemistry of the derivatization is unique to the detection of the molecules of ethylene glycol and 1,2-propylene glycol. 1,3-propylene glycol could also be detected but is not used in any known anti-freeze at this time. Other coolant analyses are beyond the scope of this test method.  
1.4 The derivatization process does not affect glycol breakdown products such as glycolate and formate and hence the presence of these compounds in the oil will not be quantified.  
1.5 The test method concentration range is from 50 µg/g to 1000 µg/g. Lower levels are possible by method modifications. Higher levels are possible through sample dilution.  
1.6 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.7 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.  
1.8 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-Sep-2023
• ICS: 75.100 - Lubricants, industrial oils and related products
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.04.0L - Gas Chromatography Methods

Relations

• Replaces: ASTM D7922-21 - Standard Test Method for Determination of Glycol for In-Service Engine Oils by Gas Chromatography
• Effective Date: 01-Oct-2023
• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• Refers: ASTM D4175-23 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023

Overview

ASTM D7922-23 – Standard Test Method for Determination of Glycol for In-Service Engine Oils by Gas Chromatography provides a robust process for detecting and quantifying glycol-based antifreeze contamination in lubricating oils currently in service. Using derivative headspace/gas chromatography, this international standard enables precise analysis of ethylene glycol and 1,2-propylene glycol within used engine oils. Monitoring glycol content is essential for diagnosing engine health, preventing equipment failure, and maintaining optimal performance.

Key Topics

• Purpose and Scope: This standard method is designed exclusively for determining glycol-based antifreeze in in-service engine oils, specifically targeting ethylene glycol and 1,2-propylene glycol. Other coolants or breakdown products such as glycolate and formate are not within its analytical scope.
• Analytical Technique: Samples are derivatized directly in a sealed headspace vial before vapor phase extraction and gas chromatographic analysis.
• Concentration Range: The method is validated for glycol concentrations from 50 µg/g to 1000 µg/g. With modifications, lower levels can be detected, and higher levels can be addressed through dilution.
• Limitations: The analysis does not quantify glycol breakdown products. The concentration of glycol found in unused engine oils is typically below the threshold of concern, preventing false positives.
• Units of Measurement: All results are reported in SI units for global consistency.

Applications

• Used Oil Analysis: Widely used by oil analysis laboratories, automotive maintenance programs, and fleet operators to detect leaks or abnormal coolant ingress in engines.
• Predictive Maintenance: Early identification of elevated glycol levels allows maintenance teams to take corrective action before significant wear or catastrophic engine failure occurs.
• Quality Control: Engine manufacturers and rebuilders rely on this method for post-assembly and service checks to ensure engine health and warranty compliance.
• Industrial Engines: Extends to heavy equipment, generators, and marine engines where oil life and equipment reliability are critical.

By enabling rapid and accurate detection of glycol contamination, ASTM D7922-23 helps prevent lubricant degradation, bearing damage, and engine seizure-directly supporting reliability-centered maintenance and operational safety.

Related Standards

• ASTM D4175: Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• ASTM D4291: Test Method for Trace Ethylene Glycol in Used Engine Oil
• ASTM E355: Practice for Gas Chromatography Terms and Relationships
• ASTM E594: Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
• ASTM E1510: Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs

Practical Value

Implementing ASTM D7922-23 offers several benefits:

• Engine Protection: Quantification of glycol-based antifreeze in lubricating oils helps prevent costly equipment damage and unscheduled downtime.
• Compliance and Warranty: Ensures adherence to industry best practices and engine warranty requirements.
• Decision Support: Empowers maintenance personnel with actionable data for timely repairs or oil changes.
• Reproducible and Reliable: The standard’s precise calibration and analytical technique deliver consistent and reproducible results, essential for monitoring long-term engine health.

Keywords

antifreeze, ethylene glycol, gas chromatography, headspace analysis, engine oil, oil analysis, lubricating oil, glycol detection, ASTM D7922-23, predictive maintenance, industrial engines, quality control.

For more information or access to the official standard, visit ASTM International.

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: D7922 − 23
Standard Test Method for
Determination of Glycol for In-Service Engine Oils by Gas
Chromatography
This standard is issued under the fixed designation D7922; 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* 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers the determination of glycol
D4175 Terminology Relating to Petroleum Products, Liquid
based antifreeze for in-service engine oil by derivative
Fuels, and Lubricants
headspace/gas chromatography.
D4291 Test Method for Trace Ethylene Glycol in Used
1.2 Sample is derivatized in-situ directly in a headspace
Engine Oil
sampling vial prior to vapor phase extraction and injection into
E355 Practice for Gas Chromatography Terms and Relation-
a gas chromatograph.
ships
E594 Practice for Testing Flame Ionization Detectors Used
1.3 The chemistry of the derivatization is unique to the
in Gas or Supercritical Fluid Chromatography
detection of the molecules of ethylene glycol and 1,2-
E1510 Practice for Installing Fused Silica Open Tubular
propylene glycol. 1,3-propylene glycol could also be detected
Capillary Columns in Gas Chromatographs
but is not used in any known anti-freeze at this time. Other
coolant analyses are beyond the scope of this test method.
3. Terminology
1.4 The derivatization process does not affect glycol break-
3.1 Definitions:
down products such as glycolate and formate and hence the
3.1.1 This test method makes reference to common gas
presence of these compounds in the oil will not be quantified.
chromatographic procedures, terms, and relationships. Detailed
1.5 The test method concentration range is from 50 μg/g to
definitions of these can be found in Practices E355 and E594
1000 μg ⁄g. Lower levels are possible by method modifications.
and Terminology D4175.
Higher levels are possible through sample dilution.
3.1.2 antifreeze, n—antifreeze is typically a dilution of
ethylene glycol and possibly other glycols, and additives, in
1.6 Units—The values stated in SI units are to be regarded
water to act as a machine coolant. 1,2-propanediol is found in
as standard. No other units of measurement are included in this
some antifreeze formulations.
standard.
3.1.3 derivitization reagent, n—a saturated solution of phe-
1.7 This standard does not purport to address all of the
nylboronic acid (PBA) in solvent. Acetone and 2,2-
safety concerns, if any, associated with its use. It is the
dimethoxypropane have been used successfully. Gentle warm-
responsibility of the user of this standard to establish appro-
ing at 50 °C will hasten dissolution. Solution is stable for three
priate safety, health, and environmental practices and deter-
months at room temperature if kept away from moisture.
mine the applicability of regulatory limitations prior to use.
3.1.4 glycol, n—the amount, expressed as a percentage, of
1.8 This international standard was developed in accor-
glycol found in the in-service lubricating oil. The most
dance with internationally recognized principles on standard-
common glycol formulated into antifreeze is ethylene glycol
ization established in the Decision on Principles for the
(CAS# 107-21-1) with some antifreeze also containing 1,2-
Development of International Standards, Guides and Recom-
propanediol also known as propylene glycol (CAS# 57-55-6).
mendations issued by the World Trade Organization Technical
Another glycol such as 1,3-propanediol (CAS# 504-63-2) is
Barriers to Trade (TBT) Committee.
detected by this test method but is not commonly used in
antifreeze formulations.
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.04.0L on Gas Chromatography Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2023. Published October 2023. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2014. Last previous edition approved in 2021 as D7922 – 21. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D7922-23. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7922 − 23
3.1.5 glycols, n—the summed amount of individual glycols 6.6 Diesel fuel in the oil along with the glycols will be seen
found in the in-service lubricating oil. in the chromatogram. Oven conditions are chosen to minimize
co-elution of diesel peaks with the ethylene glycol. Other
3.1.6 in-service oil, n—lubricating oil that is present in a
medium petroleum distillates in the oil could interfere with the
machine that has been at operating temperature for at least 1 h.
ethylene glycol peak but will be noticeable on the chromato-
4. Summary of Test Method
gram.
4.1 A representative aliquot of in-service engine oil is
6.7 Headspace vial crimp is extremely critical to completely
introduced into a headspace sampling vial along with a
seal the vial.
derivatizing agent. The headspace vial is heated to volatilize
6.8 As an external standard method, measurement of oil
the derivatized glycol into the vapor phase. Using a small
volume is critical and should be performed with a positive
aliquot of sample and derivatization reagent approaches a total
vaporization technique to minimize partition coefficient differ- displacement pipette.
ences in in-service oil samples. A representative aliquot of the
6.9 Daily column bake-out is recommended to get rid of
vapor sample is introduced to the gas chromatograph. Carrier
fuel and high molecular weight artifacts.
gas transports the vaporized aliquot through the dimethyl
polysiloxane bonded phase capillary column where the glycols
6.10 Some higher quality oils may have a small quantity of
are separated by the chromatographic process. The detector
ethylene glycol in the new, unused motor oil as part of the oil
signal is processed by an electronic data acquisition system.
formulation. This concentration has been observed at about
The components are identified by comparing their retention
30 μg ⁄g to 75 μg ⁄g which is well under the level of interest of
times to ones identified by analyzing standards under identical
100 μg ⁄g to 1000 μg ⁄g. This ethylene glycol will typically boil
conditions. The concentrations of all components are deter-
off in the heat of the engine. But a small level of ethylene
mined by percent area by normalization of the peak areas.
glycol should not be considered as a definite coolant leak
without considering the possibility of ethylene glycol in new or
5. Significance and Use
recently topped off engine oil.
5.1 Some glycol/antifreeze dilution of in-service engine oil
is normal under typical operating conditions. However, exces-
7. Apparatus
sive glycol dilution can lead to decreased performance, prema-
7.1 Gas Chromatograph (GC)—The following gas chro-
ture wear, or sudden engine failure. This test method provides
matographic system performance characteristics are required:
a means of quantifying the level of glycol based antifreeze
dilution, allowing the user to take necessary action.
7.2 Detector—This test method requires a flame ionization
detector (FID). The detector must have sufficient sensitivity to
6. Interferences
detect 50 μg/g ethylene glycol by area on the data acquisition
6.1 PBA is slightly volatile and can reach the headspace
device under the conditions prescribed in this test method. The
(HS) injector head and the transfer line. It is recommended to
detector must meet or exceed the specifications as detailed in
periodically inspect a blank injection chromatogram for carry
Practice E594. The detector must be capable of operating
over caused by condensation of PBA in the headspace sam-
continuously at 250 °C and connected to the column such that
pling head and/or transfer line. Several 10 μL injections of
no temperature zones below the column temperature (cold
water:methanol (50:50) through the headspace will consume
spots) exist.
any residual derivatizing reagent.
7.3 Injector—The preferred injector is an automated head-
6.2 The most common failure for this glycol method is
space sampling device. Connection of the headspace device to
improperly agitated standards which allow settling of glycols
the GC column can be direct or interfaced using a split/spitless
out of the oil base. Polar glycols do not stay in the non-polar
GC inlet.
oil. It is more correctly considered a suspension rather than a
solution. Every oil, sample or standard, must be shaken briskly
7.4 Pneumatic Controllers—The headspace sampler and gas
for 15 s to 20 s before sampling.
chromatograph must be capable of maintaining carrier gas
6.3 Water/humidity reaching PBA will deactivate the PBA pressure constant to 61 % for both the injector and the
and inhibit derivatization of glycols. PBA will derivatize any detector. Most modern gas chromatographs can control carrier
hydroxyl functional group. Store PBA in a desiccator, never in gas in either pressure control mode or flow control mode. This
a refrigerator.
analysis uses isothermal oven temperature therefore constant
flow control will not improve chromatographic throughput or
6.4 Buy PBA in small quantities to be replaced at six month
efficiency. At isothermal oven temperatures, both pressure and
intervals rather than larger, more cost effective quantities.
flow will remain constant.
6.5 Headspace carrier pressure must be higher than pressure
7.5 Column Conditions—This test method utilizes a fused
in the heated vial to allow pressurization of the vial to a
silica open tubular column with 5 % diphenyl and 95 %
constant pressure. This vial pressure is a function of which
solvent is used and the thermostatting temperature of the vial. dimethyl polysiloxane crossbonded phase internal coating
operating isothermally at 90 °C to 140 °C, depending on the
A pressure of 276 kPa (40 psi) has been shown to be
successful. carrier gas used.
D7922 − 23
7.5.1 Open tubular column with a cross bond 5 % diphenyl 8.1.6 2,2-dimethoxypropane CAS# 77-76-9, 99+ percent
95 % dimethyl polysiloxane phase internal coating, 15 m by pure. (Warning—Extremely flammable and toxic liquid.) One
0.32 mm I.D. with a 0.25 μm film thickness. Never use a polar of the solvents that can be used to dissolve the phenylboronic
column. acid.
8.1.7 Derivitization Reagent Solution—Prepared by dissolv-
7.6 Sample Introduction Devices:
ing dry phenylboronic acid into solvent such as acetone or
7.6.1 Headspace Automatic Sampler—An automatic sam-
2,2-dimethoxypropane. A high concentration or saturated so-
pling device for heating samples to transfer volatile compo-
lution is preferred. 0.5 g/mL phenylboronic acid in acetone will
nents into the vapor phase and injecting a reproducible and
dissolve very slowly to overnight with agitation. A gentle
representative aliquot of the vapor phase into the gas chro-
heating to 50 °C for 5 min will facilitate PBA into solution.
matograph.
Make enough volume for weekly use. Do not make large
7.7 Electronic Data Acquisition System—Any data acquisi-
volumes that will be deactivated by humidity.
tion and integration device used for quantification of these
8.2 Gas—The following compressed gases are utilized for
analyses must meet or exceed these minimum requirements:
the operation of the gas chromatograph.
7.7.1 Normalized percent calculations based on peak area or
8.2.1 Helium, 99.999 %. (Warning—Compressed gas un-
peak height.
der high pressure.) This gas can be used as carrier gas. Ensure
7.7.2 Ability to construct a first order linear regression
sufficient pressure for a constant carrier gas flow rate. Precision
calibration curve up to five levels of calibration.
is based on helium as the carrier gas; however, hydrogen and
7.7.3 Identification of individual components based on re-
nitrogen have been successfully used as carrier gas.
tention time.
7.7.4 Baseline corrections for positive or negative sloping 8.2.2 Hydrogen, 99.999 %. (Warning—Extremely flam-
mable compressed gas under high pressure.) This gas is used to
baseline.
7.7.5 Ability to turn on and off integration. supply fuel to the flame ionization detector (FID) detector.
Hydrogen is the preferred carrier. A hydrogen generator is
7.7.6 Ability to adjust integration stop and start of each
component. preferred to cylinders.
8.2.3 Nitrogen, 99.999 %. (Warning—Compressed gas un-
8. Reagents and Materials
der high pressure.) Used as an alternative carrier gas.
8.1 Purity of Reagents—Reagent grade chemicals shall be
8.2.4 Air—(Warning—Compressed gas under high pres-
used in all tests. Unless otherwise indicated, it is intended that
sure.) The gas is used to supply oxidant to the flame ionization
all reagents conform to the specifications of the Committee on
detector (FID). A zero air generator is preferred.
Analytical Reagents of the American Chemical Society where
such specifications are available. Other grades may be used,
9. Preparation of Apparatus
provided it is first ascertained that the reagent is of sufficiently
9.1 Gas Chromatograph Setup:
high purity to permit its use without lessening the accuracy of
9.1.1 Ins
...

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: D7922 − 21 D7922 − 23
Standard Test Method for
Determination of Glycol for In-Service Engine Oils by Gas
Chromatography
This standard is issued under the fixed designation D7922; 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 glycol based antifreeze for in-service engine oil by derivative headspace/gas
chromatography.
1.2 Sample is derivatized in-situ directly in a headspace sampling vial prior to vapor phase extraction and injection into a gas
chromatograph.
1.3 The chemistry of the derivatization is unique to the detection of the molecules of ethylene glycol and 1,2-propylene glycol.
1,3-propylene glycol could also be detected but is not used in any known anti-freeze at this time. Other coolant analyses are beyond
the scope of this test method.
1.4 The derivatization process does not affect glycol breakdown products such as glycolate and formate and hence the presence
of these compounds in the oil will not be quantified.
1.5 The test method concentration range is from 50 μg/g to 1000 μg ⁄g. Lower levels are possible by method modifications. Higher
levels are possible through sample dilution.
1.6 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.7 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.
1.8 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:
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.04.0L on Gas Chromatography Methods.
Current edition approved Nov. 1, 2021Oct. 1, 2023. Published November 2021October 2023. Originally approved in 2014. Last previous edition approved in 20142021
as D7922 – 14.D7922 – 21. DOI: 10.1520/D7922-21.10.1520/D7922-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7922 − 23
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4291 Test Method for Trace Ethylene Glycol in Used Engine Oil
E355 Practice for Gas Chromatography Terms and Relationships
E594 Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
E1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs
3. Terminology
3.1 Definitions:
3.1.1 This test method makes reference to common gas chromatographic procedures, terms, and relationships. Detailed definitions
of these can be found in Practices E355 and E594 and Terminology D4175.
3.1.2 antifreeze, n—antifreeze is typically a dilution of ethylene glycol and possibly other glycols, and additives, in water to act
as a machine coolant. 1,2-propanediol is found in some antifreeze formulations.
3.1.3 derivitization reagent, n—a saturated solution of phenylboronic acid (PBA) in solvent. Acetone and 2,2-dimethoxypropane
have been used successfully. Gentle warming at 50 °C will hasten dissolution. Solution is stable for three months at room
temperature if kept away from moisture.
3.1.4 glycol, n—the amount, expressed as a percentage, of glycol found in the in-service lubricating oil. The most common glycol
formulated into antifreeze is ethylene glycol (CAS# 107-21-1) with some antifreeze also containing 1,2-propanediol also known
as propylene glycol (CAS# 57-55-6). Another glycol such as 1,3-propanediol (CAS# 504-63-2) is detected by this test method but
is not commonly used in antifreeze formulations.
3.1.5 glycols, n—the summed amount of individual glycols found in the in-service lubricating oil.
3.1.6 in-service oil, n—lubricating oil that is present in a machine that has been at operating temperature for at least 1 h.
4. Summary of Test Method
4.1 A representative aliquot of in-service engine oil is introduced into a headspace sampling vial along with a derivatizing agent.
The headspace vial is heated to volatilize the derivatized glycol into the vapor phase. Using a small aliquot of sample and
derivatization reagent approaches a total vaporization technique to minimize partition coefficient differences in in-service oil
samples. A representative aliquot of the vapor sample is introduced to the gas chromatograph. Carrier gas transports the vaporized
aliquot through the dimethyl polysiloxane bonded phase capillary column where the glycols are separated by the chromatographic
process. The detector signal is processed by an electronic data acquisition system. The components are identified by comparing
their retention times to ones identified by analyzing standards under identical conditions. The concentrations of all components are
determined by percent area by normalization of the peak areas.
5. Significance and Use
5.1 Some glycol/antifreeze dilution of in-service engine oil is normal under typical operating conditions. However, excessive
glycol dilution can lead to decreased performance, premature wear, or sudden engine failure. This test method provides a means
of quantifying the level of glycol based antifreeze dilution, allowing the user to take necessary action.
6. Interferences
6.1 Glycols tend to be sticky molecules that can lead to small carryover into blank injections.
6.1 PBA is slightly volatile and can reach the headspace (HS) injector head and the transfer line. It is recommended to periodically
inspect a blank injection chromatogram for carry over caused by condensation of PBA in the headspace sampling head and/or
transfer line. Several 10 μL injections of water:methanol (50:50) through the headspace will consume any residual derivatizing
reagent.
6.2 The most common failure for this glycol method is improperly agitated standards which allow settling of glycols out of the
oil base. Polar glycols do not stay in the non-polar oil. It is more correctly considered a suspension rather than a solution. Every
oil, sample or standard, must be shaken briskly for 15 s to 20 s before sampling.
D7922 − 23
6.3 Water/humidity reaching PBA will deactivate the PBA and inhibit derivatization of glycols. PBA will derivatize any hydroxyl
functional group. Store PBA in a desicator,desiccator, never in a refrigerator.
6.4 Buy PBA in small quantities to be replaced at six month intervals rather than larger, more cost effective quantities.
6.5 Headspace carrier pressure must be higher than pressure in the heated vial to allow pressurization of the vial to a constant
pressure. This vial pressure is a function of which solvent is used and the thermostatting temperature of the vial. A pressure of 276
kPa (40 psi) has been shown to be successful.
6.6 Diesel fuel in the oil along with the glycols will be seen in the chromatogram. Oven conditions are chosen to minimize
co-elution of diesel peaks with the ethylene glycol. Other medium petroleum distillates in the oil could interfere with the ethylene
glycol peak but will be noticeable on the chromatogram.
6.7 Headspace vial crimp is extremely critical to completely seal the vial.
6.8 As an external standard method, measurement of oil volume is critical and should be performed with a positive displacement
pipette.
6.9 Daily column bake-out is recommended to get rid of fuel and high molecular weight artifacts.
6.11 Split injection has been shown to cause ethylene glycol carryover in the injector. Therefore, direct column connection
between the headspace sampler and the analytical column is used.
6.10 Some higher quality oils may have a small quantity of ethylene glycol in the new, unused motor oil as part of the oil
formulation. This concentration has been observed at about 30 μg ⁄g to 75 μg ⁄g which is well under the level of interest of 100 μg ⁄g
to 1000 μg ⁄g. This ethylene glycol will typically boil off in the heat of the engine. But a small level of ethylene glycol should not
be considered as a definite coolant leak without considering the possibility of ethylene glycol in new or recently topped off engine
oil.
7. Apparatus
7.1 Gas Chromatograph (GC)—The following gas chromatographic system performance characteristics are required:
7.2 Detector—This test method requires a flame ionization detector (FID). The detector must have sufficient sensitivity to detect
50 μg/g ethylene glycol by area on the data acquisition device under the conditions prescribed in this test method. The detector
must meet or exceed the specifications as detailed in Practice E594. The detector must be capable of operating continuously at 250
°C and connected to the column such that no temperature zones below the column temperature (cold spots) exist.
7.3 Injector—The preferred injector is an automated headspace sampling device, with a direct connection device. Connection of
the headspace device to the analytical column without exposing the sample to a GC injector.GC column can be direct or interfaced
using a split/spitless GC inlet.
7.4 Pneumatic Controllers—The headspace sampler and gas chromatograph must be capable of maintaining carrier gas pressure
constant to 61 % for both the injector and the detector. Most modern gas chromatographs can control carrier gas in either pressure
control mode or flow control mode. This analysis uses isothermal oven temperature therefore constant flow control will not
improve chromatographic throughput or efficiency. At isothermal oven temperatures, both pressure and flow will remain constant.
7.5 Column Conditions—This test method utilizes a fused silica open tubular column with 5 % diphenyl and 95 % dimethyl
polysiloxane crossbonded phase internal coating operating isothermally at 90 °C to 140 °C, depending on the carrier gas used.
7.5.1 Open tubular column with a cross bond 5 % diphenyl 95 % dimethyl polysiloxane phase internal coating, 15 m by 0.32 mm
I.D. with a 0.25 μm film thickness. Never use a polar column.
D7922 − 23
7.6 Sample Introduction Devices:
7.6.1 Headspace Automatic Sampler—An automatic sampling device for heating samples to transfer volatile components into the
vapor phase and injecting a reproducible and representative aliquot of the vapor phase into the gas chromatograph.
7.7 Electronic Data Acquisition System—Any data acquisition and integration device used for quantification of these analyses
must meet or exceed these minimum requirements:
7.7.1 Normalized percent calculations based on peak area or peak height.
7.7.2 Ability to construct a first order linear regression calibration curve up to five levels of calibration.
7.7.3 Identification of individual components based on retention time.
7.7.4 Baseline corrections for positive or negative sloping baseline.
7.7.5 Ability to turn on and off integration.
7.7.6 Ability to adjust integration stop and start of each component.
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 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 Phenylboronic acid CAS# 98-80-6, 99+ percent pure.Used as a derivatizing reagent to convert ethylene glycol and other low
molecular weight glycols to the phenylboronic derivative of the glycol.
8.1.2 Ethylene glycol CAS# 107-21-1, 99+ percent pure.Used as a calibration standard for retention time and quantitative response
by concentration.
8.1.3 Propylene glycol CAS# 57-55-6, 99+ percent pure.Also known as 1,2-propanediol. Used as a calibration standard for
retention time and quantitative response by concentration.
8.1.4 1,3-propanediol CAS# 504-63-2, 99+ percent pure.Used as a calibration standard for retention time and quantitative response
by concentration. Not essential in most antifreeze formulations. Used primarily to insure resolution of 1,2-propanediol from
1,3-propanediol.
8.1.5 Acetone, CAS# 67-64-1, 99+ percent pure.(Warning—Extremely flammable and toxic liquid.) One of the solvents that can
be used to dissolve the phenylboronic acid.
8.1.6 2,2-dimethoxypropane CAS# 77-76-9, 99+ percent pure.(Warning—Extremely flammable and toxic liquid.) One of the
solvents that can be used to dissolve the phenylboronic acid.
8.1.7 Derivitization Reagent Solution—Prepared by dissolving dry phenylboronic acid into solvent such as acetone or
2,2-dimethoxypropane. A high concentration or saturated solution is preferred. 0.5 g/mL phenylboronic acid in acetone will
dissolve very slowly to overnight with agitation. A gentle heating to 50 °C for 5 min will facilitate PBA into solu
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