ASTM D5837-99(2005)
(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
Furanic compounds are generated by the degradation of cellulosic materials used in the solid insulation systems of electrical equipment.
Furanic compounds which are oil soluble to an appreciable degree will migrate into the insulating liquid.
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 D 3612.
SCOPE
1.1 This test method describes 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-furaldehydefurfuryl alcohol2-furaldehyde2-acetylfuran5-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.
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.
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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
Designation:D5837–99 (Reapproved 2005)
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 2. Referenced Documents
1.1 This test method covers the determination in electrical 2.1 ASTM Standards:
insulating liquids of products of the degradation of cellulosic D923 Practices for Sampling Electrical Insulating Liquids
materials such as paper, pressboard, and cotton materials D3487 Specification for Mineral Insulating Oil Used in
typically found as insulating materials in electrical equipment. Electrical Apparatus
These degradation products are substituted furan derivatives, D3612 Test Method for Analysis of Gases Dissolved in
commonly referred to as furanic compounds or furans. This Electrical Insulating Oil by Gas Chromatography
testmethodallowseitherliquid/liquidorsolidphaseextraction D3613 Practice for Sampling Insulating Liquids for Gas
(SPE) of the furanic compounds from the sample matrix Analysis and Determination of Water Content
followed by analysis for specific furanic compounds by HPLC 2.2 International Electrotechnical Commission (IEC) Stan-
or direct injection for analysis of specific furanic compounds dard:
by HPLC. Method 1198 Furanic Compounds Analysis in Mineral Oil
1.2 The individual furanic compounds that may be identi- Insulating Oil
fied and quantified include the following:
3. Terminology
5-hydroxymethyl-2-furaldehyde
furfuryl alcohol
3.1 Definitions of Terms Specific to This Standard:
2-furaldehyde
3.1.1 adsorbent, n—the stationary phase in solid-phase
2-acetylfuran
extraction; silica is used as the adsorbent in this test method.
5-methyl-2-furaldehyde
3.1.2 extract, n—the liquid phase of a liquid/liquid extrac-
1.3 The direct injection method generally has a higher limit
tion containing the compound that has been extracted and that
of detection, especially for furfuryl alcohol. Greater interfer-
will be analyzed.
ence for furfuryl alcohol may be expected when using the
3.1.3 liquid/liquid extraction, n—the preparative step of
direct injection method as opposed to extraction methods.
extractionbymixingnonpolartestspecimenwithpolarsolvent
1.4 This test method has been used to successfully test for
to preferentially partition and concentrate polar compounds of
furanic compounds in mineral insulating oil, silicone fluid,
interest from an insulating liquid test specimen.
high fire point electrical insulating oils of mineral origin,
3.1.4 mobile phase, n—the carrier liquid phase in an HPLC
askarels, and perchloroethylene-based dielectric fluids.
analytical system used to transfer the prepared test specimen to
1.5 The values stated in SI units are to be regarded as
and through the analytical column and detector; the composi-
standard. No other units of measurement are included in this
tion of the mobile phase affects elution time and separation of
standard.
analytes.
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 appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
This test method is under the jurisdiction of ASTM Committee D27 on Standards volume information, refer to the standard’s Document Summary page on
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom- the ASTM website.
mittee D27.03 on Analytical Tests. Withdrawn. The last approved version of this historical standard is referenced
Current edition approved Oct. 1, 2005. Published November 2005. Originally on www.astm.org.
´1 4
approved in 1995. Last previous edition approved in 1999 as D5837 – 99 . DOI: Available from IEC, IEC Central Office, 3 rue de Varembe, P.O. Box 131,
10.1520/D5837-99R05. CH-1211, Geneva 20, Switzerland.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5837–99 (2005)
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 to
7.4 The analytical apparatus may be heated several degrees
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 to 380 nm.
analytical results that may be caused by temperature fluctua-
tions. Operation at ambient temperature or at a controlled
4. Summary of Test Method
temperature of 30 to 40°C has been found satisfactory by some
4.1 Furanic compounds in electrical insulating liquids are
laboratories.
extracted from a known volume of test specimen by means of
7.5 The following range of HPLC analytical conditions has
a liquid/liquid extraction or solid-phase extraction. A direct
been found to be satisfactory for extracted test specimens
injection of the oil also may be used.
(specific examples are given in the appendix):
4.2 A portion of the extract or an aliquot of the oil is
Injection Volume 15 to 30 µL
introduced into an HPLC system equipped with a suitable
Mobile Phase water/acetonitrile or water/methanol gradient
Flow Rate 0.5 mL/min to 1.5 mL/min
analytical column and UV detector.
Column Temperature ambient to 40°C
4.3 Furanic compounds in the test specimen are identified
Column 3.9 3 300 mm C18 60 to 125A, 4 to 10 µm or 4.1 3 150
and quantified by comparison to standards of known concen-
mm PRP-1 100 A, 5 to 10 µm
Gradient see appendix
tration.
NOTE 1—Some laboratories have found it beneficial to filter all mobile
5. Significance and Use
phase solvents with a 0.45-µm or smaller polytetrafluoroethylene or nylon
filter. Store water in containers shielded from light. Some laboratories use
5.1 Furanic compounds are generated by the degradation of
50 mL of methanol added to 4 L of water to inhibit biological growth.
cellulosic materials used in the solid insulation systems of
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 to 30 µL
Mobile phase acetonitrile/water gradient
5.3 High concentrations or unusual increases in the concen-
Flow rate, initial 0.5–1.0 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 WatersT Nova-Pak C18 Reversed Phased 300 3 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
Method D3612.
7.7 For direct injection, a fixed wavelength between 274
and281nmhasbeenfoundtoprovidethebestchromatography
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 and 220 nm. Each furanic compound has a characteristic
tubes and polyethylene frits of some commercially prepared
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
arraydetectorsallowstheselectionofaspecificwavelengthfor
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 Theuseofcellulosicfilteringmediamayservetoadsorb
5-hydroxymethyl-2-furaldehyde 280 to 282
furanic compounds yielding erroneous or unreproducible re-
furfuryl alcohol 215 to 220
sults, or both.
2-furaldehyde 272 to 280
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 to 15 min for the column to
integrator. come to equilibrium prior to the next injection.
D5837–99 (2005)
8. Reagents and Materials 10.1.2.1 Thesevolumesrepresentamassof1000µgofeach
of the five furanic compounds. Add 10 mL of acetonitrile or
8.1 Acetonitrile—HPLC grade.
methanol containing the dissolved volumes of furanic com-
8.2 2-Acetylfuran—99 % purity, CAS #1192-62-7.
pounds to 190 mL of the same solvent in a 1-L volumetric
8.3 Electrical Insulating Oil—Virgin oil of mineral origin.
flask. Bring this solution to 1 L with water. Other ratios of
8.4 2-Furaldehyde—99 % purity, CAS #98-01-1.
solvent to water can be used such as to match that of the initial
8.5 Furfuryl Alcohol—99 % purity, CAS #98-00-0.
mobile phase. The resulting concentration is 1 mg/L (1000
8.6 Hexane—HPLC grade.
µg/L) for each of the five furanic compounds. Store as
8.7 5-Hydroxymethyl-2-Furaldehyde—99 % purity, CAS
indicated in 10.1.1.
#67-47-0.
8.8 Methanol—HPLC grade.
11. Preparation of Calibration Standards in Oil
8.9 5-Methyl-2-furaldehyde—99 % purity, CAS #620-02-0.
11.1 Prepare standards of furanic compounds in new dielec-
8.10 Silica SPE Column—Solid-phase extraction column
tric liquid which has been tested and shown to have a flat
filled with 500 mg of silica.
baseline for the range of retention times for the compounds of
8.11 Toluene—HPLC grade.
interest. Mineral oil shall otherwise conform to Specification
8.12 Vacuum Manifold—Device to pull vacuum on solid-
D3487.Otherdielectricliquidsshouldconformwithapplicable
phase extraction column in order to pass sample and eluent
ASTM specifications.
through SPE column.
8.13 Volumetric Test Tube—Test tube designed to volu- 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
metrically measure in 0.10-mL graduations.
method has been developed for mineral oil, but has been found to be
8.14 Vortex Mixer.
applicable to other dielectric fluids.
8.15 Water—HPLC grade.
11.2 Volumetric Preparation:
11.2.1 Useagraduated1-µLsyringetoinjectvolumesofthe
9. Sampling
fivefuraniccompoundsaslistedin10.1.2into8mLoftoluene.
9.1 Obtain test specimens (insulating fluid samples) in
Dissolve the compounds and add quantitatively to a 1-L
accordancewiththeproceduresforsamplinginPracticesD923
volumetric flask. Make sure all compounds are thoroughly
or Practice D3613.
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 Lwith electrical insulating oil of
10.1 Prepare the extraction standards by dilution of a
mineral origin. The solution yields a concentration of 1 mg/L
weighed standard compound to a standard volume or by
(1000 µg/L) of each of the five furanic compounds. Store as
volumetric addition of a standard compound to a standard
described in 10.1.1.
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
compounds and record the weight to the nearest 0.1 mg.
each of the five furanic compounds listed in this test method
Dissolve the weighed portion in toluene and dilute volumetri-
and 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 mLof acetonitrile or methanol.Take 1 mLof
furanic compounds are dissolved completely.
this solution and add to a clean 1-L volumetric flask. Add 199
11.3.2 Volumetrically dilute 1 mL of the toluene solution
mLofeitheracetonitrileormethanol,usingthesamesolventas
from 11.3.1 to 1 L using electrical insulating oil of mineral
was used earlier to dissolve the weighed portions of the furanic
origin. This solution of furanic compounds in oil yields a
compounds. Bring the solution in the volumetric flask to 1 L
concentration of about 1 mg/L (1000 µg/L) for each of the
with water. Other ratios of solvent to water may be used such
furanic compounds. Use the actual mass of each compound
astomatchthatoftheinitialmobilephase.Thissolutionyields
recorded in 11.3.1 to calculate the exact concentration in the
a concentration of about 1 mg/L (1000 µg/L) of each of the
resulting solution. Store as described in 10.1.1.
furanic compounds. Use the actual mass of each compound to
calculate the concentration. Store in a clean, dark plastic
12. Liquid/Liquid Extraction Procedure—Method A
container. Do not store in glass.
12.1 Measure 1 to 2 mLof the extraction solvent (methanol,
10.1.2 Volumetric Addition—Furanic compounds that are
acetonitrile, or methanol/acetonitrile) into 10 mL of the test
not liquid at ambient temperature should be heated to 35°C
specim
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