ASTM D5837-15(2023)
(Test Method)Standard Test Method for Furanic Compounds in Electrical Insulating Liquids by High-Performance Liquid Chromatography (HPLC)
Standard Test Method for Furanic Compounds in Electrical Insulating Liquids by High-Performance Liquid Chromatography (HPLC)
SIGNIFICANCE AND USE
5.1 Furanic compounds are generated by the degradation of cellulosic materials used in the solid insulation systems of electrical equipment.
5.2 Furanic compounds which are oil soluble to an appreciable degree will migrate into the insulating liquid.
5.3 High concentrations or unusual increases in the concentrations of furanic compounds in oil may indicate cellulose degradation from aging or incipient fault conditions. Testing for furanic compounds may be used to complement dissolved gas in oil analysis as performed in accordance with Test Method D3612.
SCOPE
1.1 This test method covers the determination in electrical insulating liquids of products of the degradation of cellulosic materials such as paper, pressboard, and cotton materials typically found as insulating materials in electrical equipment. These degradation products are substituted furan derivatives, commonly referred to as furanic compounds or furans. This test method allows either liquid/liquid or solid phase extraction (SPE) of the furanic compounds from the sample matrix followed by analysis for specific furanic compounds by HPLC or direct injection for analysis of specific furanic compounds by HPLC.
1.2 The individual furanic compounds that may be identified and quantified include the following:
5-hydroxymethyl-2-furaldehyde
furfuryl alcohol
2-furaldehyde
2-acetylfuran
5-methyl-2-furaldehyde
1.3 The direct injection method generally has a higher limit of detection, especially for furfuryl alcohol. Greater interference for furfuryl alcohol may be expected when using the direct injection method as opposed to extraction methods.
1.4 This test method has been used to successfully test for furanic compounds in mineral insulating oil, silicone fluid, high fire point electrical insulating oils of mineral origin, askarels, and perchloroethylene-based dielectric fluids.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 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.
1.7 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
Relations
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: D5837 − 15 (Reapproved 2023)
Standard Test Method for
Furanic Compounds in Electrical Insulating Liquids by High-
Performance Liquid Chromatography (HPLC)
This standard is issued under the fixed designation D5837; 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 1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This test method covers the determination in electrical
ization established in the Decision on Principles for the
insulating liquids of products of the degradation of cellulosic
Development of International Standards, Guides and Recom-
materials such as paper, pressboard, and cotton materials
mendations issued by the World Trade Organization Technical
typically found as insulating materials in electrical equipment.
Barriers to Trade (TBT) Committee.
These degradation products are substituted furan derivatives,
commonly referred to as furanic compounds or furans. This
2. Referenced Documents
test method allows either liquid/liquid or solid phase extraction
2.1 ASTM Standards:
(SPE) of the furanic compounds from the sample matrix
D923 Practices for Sampling Electrical Insulating Liquids
followed by analysis for specific furanic compounds by HPLC
D3487 Specification for Mineral Insulating Oil Used in
or direct injection for analysis of specific furanic compounds
Electrical Apparatus
by HPLC.
D3612 Test Method for Analysis of Gases Dissolved in
1.2 The individual furanic compounds that may be identi-
Electrical Insulating Oil by Gas Chromatography
fied and quantified include the following:
2.2 IEC Standard:
5-hydroxymethyl-2-furaldehyde
Method 1198 Furanic Compounds Analysis in Mineral Oil
furfuryl alcohol
2-furaldehyde Insulating Oil
2-acetylfuran
5-methyl-2-furaldehyde
3. Terminology
1.3 The direct injection method generally has a higher limit
3.1 Definitions of Terms Specific to This Standard:
of detection, especially for furfuryl alcohol. Greater interfer-
3.1.1 adsorbent, n—the stationary phase in solid-phase ex-
ence for furfuryl alcohol may be expected when using the
traction; silica is used as the adsorbent in this test method.
direct injection method as opposed to extraction methods.
3.1.2 extract, n—the liquid phase of a liquid/liquid extrac-
1.4 This test method has been used to successfully test for
tion containing the compound that has been extracted and that
furanic compounds in mineral insulating oil, silicone fluid,
will be analyzed.
high fire point electrical insulating oils of mineral origin,
3.1.3 liquid/liquid extraction, n—the preparative step of
askarels, and perchloroethylene-based dielectric fluids.
extraction by mixing nonpolar test specimen with polar solvent
1.5 The values stated in SI units are to be regarded as
to preferentially partition and concentrate polar compounds of
standard. No other units of measurement are included in this
interest from an insulating liquid test specimen.
standard.
3.1.4 mobile phase, n—the carrier liquid phase in an HPLC
1.6 This standard does not purport to address all of the
analytical system used to transfer the prepared test specimen to
safety concerns, if any, associated with its use. It is the
and through the analytical column and detector; the composi-
responsibility of the user of this standard to establish appro-
tion of the mobile phase affects elution time and separation of
priate safety, health, and environmental practices and deter-
analytes.
mine the applicability of regulatory limitations prior to use.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method is under the jurisdiction of ASTM Committee D27 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom- Standards volume information, refer to the standard’s Document Summary page on
mittee D27.03 on Analytical Tests. the ASTM website.
Current edition approved Dec. 1, 2023. Published January 2024. Originally Available from International Electrotechnical Commission (IEC), 3, rue de
approved in 1995. Last previous edition approved in 2015 as D5837 – 15. DOI: Varembé, 1st floor, P.O. Box 131, CH-1211, Geneva 20, Switzerland, https://
10.1520/D5837-15R23. www.iec.ch.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5837 − 15 (2023)
3.1.5 solid phase extraction (SPE), n—a preparative step 7.2 It is recommended that a precolumn packed with the
based on column chromatography, where intermolecular inter- same material as the analytical column be used to increase
actions between adsorbent, solvent, and test specimen compo- column life and remove interferences.
nents are optimized to effect retention of analytes on a
7.3 Helium sparging of the mobile-phase solvents is recom-
solid-phase extraction cartridge, followed by solvent elution
mended in some cases and with some types of HPLC equip-
from the extraction cartridge.
ment to displace atmospheric gases dissolved in the mobile-
3.1.6 ultraviolet (UV), adj—referring to that region of the
phase solvents and to prevent the evolution of air bubbles.
electromagnetic spectrum including wavelengths from 10 nm
7.4 The analytical apparatus may be heated several degrees
to 380 nm. The UV detectors of most HPLC systems operate in
Celsius above ambient if necessary to reduce variance in
the range of wavelengths from 190 nm to 380 nm.
analytical results that may be caused by temperature fluctua-
4. Summary of Test Method
tions. Operation at ambient temperature or at a controlled
temperature of 30 °C to 40 °C has been found satisfactory by
4.1 Furanic compounds in electrical insulating liquids are
some laboratories.
extracted from a known volume of test specimen by means of
a liquid/liquid extraction or solid-phase extraction. A direct
7.5 The following range of HPLC analytical conditions has
injection of the oil also may be used.
been found to be satisfactory for extracted test specimens
(specific examples are given in the appendix):
4.2 A portion of the extract or an aliquot of the oil is
introduced into an HPLC system equipped with a suitable Injection Volume 15 μL to 30 μL
Mobile Phase water/acetonitrile or water/methanol gradient
analytical column and UV detector.
Flow Rate 0.5 mL/min to 1.5 mL/min
Column Temperature ambient to 40 °C
4.3 Furanic compounds in the test specimen are identified
Column 3.9 × 300 mm C18 60 to 125A, 4 μm to 10 μm or
and quantified by comparison to standards of known concen-
4.1 × 150 mm PRP-1 100 A, 5 μm to 10 μm
tration.
Gradient see appendix
5. Significance and Use
NOTE 1—Some laboratories have found it beneficial to filter all mobile
phase solvents with a 0.45 μm or smaller polytetrafluoroethylene or nylon
5.1 Furanic compounds are generated by the degradation of
filter. Store water in containers shielded from light. Some laboratories use
cellulosic materials used in the solid insulation systems of
50 mL of methanol added to 4 L of water to inhibit biological growth.
electrical equipment.
7.6 The following HPLC analytical conditions have been
5.2 Furanic compounds which are oil soluble to an appre-
found to be satisfactory for direct injection of the oil:
ciable degree will migrate into the insulating liquid.
Injection volume 20 μL to 30 μL
Mobile phase acetonitrile/water gradient
5.3 High concentrations or unusual increases in the concen-
Flow rate, initial 0.5 mL ⁄min to 1.0 mL ⁄min
trations of furanic compounds in oil may indicate cellulose
Column temperature ambient to 30 °C
degradation from aging or incipient fault conditions. Testing Column Waters® Nova-Pak C18 Reversed Phased 300 ×
3.9 mm, 60A, 4 μm
for furanic compounds may be used to complement dissolved
Gradient see Appendix
gas in oil analysis as performed in accordance with Test
7.7 For direct injection, a fixed wavelength between 274 nm
Method D3612.
and 281 nm has been found to provide the best chromatography
6. Interferences
for all compounds of interest, except furfuryl alcohol, which is
best measured with a separate test using a wavelength between
6.1 Materials used in the manufacture of the polypropylene
215 nm and 220 nm. Each furanic compound has a character-
tubes and polyethylene frits of some commercially prepared
istic maximum light absorbance occurring within the indicated
solid-phase extraction columns may interfere with the deter-
ranges of wavelengths. Use of variable wavelength or diode
mination of furanic compounds, such as furfuryl alcohol and
array detectors allows the selection of a specific wavelength for
5-hydroxymethyl-2-furaldehyde.
each furanic compound. Each laboratory shall select the
6.2 The use of acetone in any preparative or analytical step
specific wavelength to yield maximum absorbance for each
will cause accelerated sample decay and may interfere with the
compound as follows:
accurate determination of 5-hydroxymethyl-2-furaldehyde.
Furanic Compound nm
6.3 The use of cellulosic filtering media may serve to adsorb
5-hydroxymethyl-2-furaldehyde 280 to 282
furfuryl alcohol 215 to 220
furanic compounds yielding erroneous or unreproducible
2-furaldehyde 272 to 280
results, or both.
2-acetyl furan 270 to 280
5-methyl-2-furaldehyde 280 to 292
7. Apparatus
7.8 After the last compound of interest elutes through the
7.1 High-Performance Liquid Chromatograph (HPLC)—
column, increase the acetonitrile or methanol to 100 % of the
The required analytical apparatus, an HPLC, consists of an
mobile phase to remove all oil contamination remaining in the
injection device with sample loop, pumping system capable of
analytical column.
mixing at least two solvents, reversed phase analytical column,
UV detector or detectors with the ability to operate at a 7.9 Readjust the solvent ratio of the mobile phase to the
minimum of two wavelengths, and a data recording device or initial conditions and allow 10 min to 15 min for the column to
integrator. come to equilibrium prior to the next injection.
D5837 − 15 (2023)
8. Reagents and Materials syringe to add the indicated volumes of furanic compounds to
10 mL of acetonitrile or methanol. The volumes to be added are
8.1 Acetonitrile—HPLC grade.
as follows:
8.2 2-Acetylfuran—99 % purity, CAS #1192-62-7.
0.83 μL ± 1 % of 5-hydroxymethyl-2-furaldehyde
0.88 μL ± 1 % of furfuryl alcohol
8.3 Electrical Insulating Oil—Virgin oil of mineral origin.
0.86 μL ± 1 % of 2-furaldehyde
0.91 μL ± 1 % of 2-acetylfuran
8.4 2-Furaldehyde—99 % purity, CAS #98-01-1.
0.90 μL ± 1 % of 5-methyl-2-furaldehyde
8.5 Furfuryl Alcohol—≥98 % purity, CAS #98-00-0.
10.1.2.1 These volumes represent a mass of 1000 μg of each
of the five furanic compounds. Add 10 mL of acetonitrile or
8.6 Hexane—HPLC grade.
methanol containing the dissolved volumes of furanic com-
8.7 5-Hydroxymethyl-2-Furaldehyde—99 % purity, CAS
pounds to 190 mL of the same solvent in a 1 L volumetric flask.
#67-47-0.
Bring this solution to 1 L with water. Other ratios of solvent to
water can be used such as to match that of the initial mobile
8.8 Methanol—HPLC grade.
phase. The resulting concentration is 1 mg/L (1000 μg/L) for
8.9 5-Methyl-2-furaldehyde—≥98 % purity, CAS #620-
each of the five furanic compounds. Store as indicated in
02-0.
10.1.1.
8.10 Silica SPE Column—Solid-phase extraction column
11. Preparation of Calibration Standards in Oil
filled with 500 mg of silica.
11.1 Prepare standards of furanic compounds in new dielec-
8.11 Toluene—HPLC grade.
tric liquid which has been tested and shown to have a flat
8.12 Vacuum Manifold—Device to pull vacuum on solid-
baseline for the range of retention times for the compounds of
phase extraction column in order to pass sample and eluent interest. Mineral oil shall otherwise conform to Specification
through SPE column.
D3487. Other dielectric liquids should conform with applicable
ASTM specifications.
8.13 Volumetric Test Tube—Test tube designed to volumetri-
cally measure in 0.10 mL graduations.
NOTE 2—The same type of dielectric liquid should be used for standard
preparation as the dielectric liquid found in the test specimen(s). This test
8.14 Vortex Mixer.
method has been developed for mineral oil, but has been found to be
applicable to other dielectric fluids.
8.15 Water—HPLC grade.
11.2 Volumetric Preparation:
11.2.1 Use a graduated 1 μL syringe to inject volumes of the
9. Sampling
five furanic compounds as listed in 10.1.2 into 8 mL of toluene.
9.1 Obtain test specimens (insulating fluid samples) in
Dissolve the compounds and add quantitatively to a 1 L
accordance with the procedures for sampling in Practices
volumetric flask. Make sure all compounds are thoroughly
D923.
mixed.
11.2.2 Dilute the 8 mL of toluene containing furanic com-
10. Preparation of Extraction Standards in Solvent
pounds to a total volume of 1 L with electrical insulating oil of
mineral origin. The solution yields a concentration of 1 mg/L
10.1 Prepare the extraction standards by dilution of a
(1000 μg/L) of each of the five furanic compounds. Store as
weighed standard compound to a standard volume or by
described in 10.1.1.
volumetric addition of a standard compound to a standard
volume in accordance with either of the procedures described
11.3 Gravimetric Preparation:
in 10.1.1 or 10.1.2.
11.3.1 Weigh out 0.100 g 6 5 % of each of the five furanic
10.1.1 Weight Procedure—Weigh out 0.100 g 6 5 % of each
compounds and record the weight to the nearest 0.1 mg.
of the five furanic compounds listed in this test method and
Dissolve the weighed portion in toluene and dilute volumetri-
record the weight to the nearest 0.1 mg. Dissolve weighed
cally to 100 mL in toluene. Mix thoroughly so that all five
portions into 100 mL of acetonitrile or methanol. Take 1 mL of
furanic compounds are dissolved completely.
this solution and add to a clean 1 L volumetric flask. Add
11.3.2 Volumetrically dilute 1 mL of the toluene solution
199 mL of either acetonitrile or methanol, using the same
from 11.3.1 to 1 L using electrical insulating oil of mineral
solvent as was used earlier to dissolve the weighed portions of
origin. This solution of furanic compounds in oil yields a
the furanic compounds. Bring the solution in the volumetric
concentration of about 1 mg/L (1000 μg/L) for each of the
flask to 1 L with water. Other ra
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