ASTM D5837-99
(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)
SCOPE
1.1 This test method covers the extraction from test specimens and detection 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 furanic compounds, commonly referred to as furan-like, furanoid, furans, or substituted furan compounds. 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.
1.2 The individual furanic compounds that may be identified and quantified include the following:
1.3 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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:D 5837–99
Standard Test Method for
Furanic Compounds in Electrical Insulating Liquids by High-
Performance Liquid Chromatography (HPLC)
This standard is issued under the fixed designation D 5837; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 3487 Specification for Mineral Insulating Oil Used in
Electrical Apparatus
1.1 This test method describes the determination in electri-
D 3612 Test Method for Analysis of Gases Dissolved in
cal insulating liquids of products of the degradation of cellu-
Electrical Insulating Oil by Gas Chromatography
losic materials such as paper, pressboard, and cotton materials
D 3613 Test Methods for Sampling Electrical Insulating
typically found as insulating materials in electrical equipment.
Oils for Gas Analysis and Determination of Water Con-
These degradation products are substituted furan derivatives,
tent
commonly referred to as furanic compounds or furans. This
2.2 International Electrotechnical Commission (IEC) Stan-
test method allows either liquid/liquid or solid phase extraction
dard:
(SPE) of the furanic compounds from the sample matrix
Method 1198 Furanic Compounds Analysis in Mineral Oil
followed by analysis for specific furanic compounds by HPLC
Insulating Oil
or direct injection for analysis of specific furanic compounds
by HPLC.
3. Terminology
1.2 The individual furanic compounds that may be identi-
3.1 Definitions of Terms Specific to This Standard:
fied and quantified include the following:
3.1.1 adsorbent, n—the stationary phase in solid-phase
5-hydroxymethyl-2-furaldehyde
extraction; silica is used as the adsorbent in this test method.
furfuryl alcohol
2-furaldehyde
3.1.2 extract, n—the liquid phase of a liquid/liquid extrac-
2-acetylfuran
tion containing the compound that has been extracted and that
5-methyl-2-furaldehyde
will be analyzed.
1.3 The direct injection method generally has a higher limit
3.1.3 liquid/liquid extraction, n—the preparative step of
of detection, especially for furfuryl alcohol. Greater interfer-
extraction by mixing nonpolar test specimen with polar solvent
ence for furfuryl alcohol may be expected when using the
to preferentially partition and concentrate polar compounds of
direct injection method as opposed to extraction methods.
interest from an insulating liquid test specimen.
1.4 This test method has been used to successfully test for
3.1.4 mobile phase, n—the carrier liquid phase in an HPLC
furanic compounds in mineral insulating oil, silicone fluid,
analytical system used to transfer the prepared test specimen to
high fire point electrical insulating oils of mineral origin,
and through the analytical column and detector; the composi-
askarels, and perchloroethylene based dielectric fluids.
tion of the mobile phase affects elution time and separation of
1.5 This standard does not purport to address all of the
analytes.
safety concerns, if any, associated with its use. It is the
3.1.5 solid phase extraction (SPE), n—a preparative step
responsibility of the user of this standard to establish appro-
based on column chromatography, where intermolecular inter-
priate safety and health practices and determine the applica-
actions between adsorbent, solvent, and test specimen compo-
bility of regulatory limitations prior to use.
nents are optimized to effect retention of analytes on a
solid-phase extraction cartridge, followed by solvent elution
2. Referenced Documents
from the extraction cartridge.
2.1 ASTM Standards:
3.1.6 ultraviolet (UV), adj—referring to that region of the
D 923 Test Method for Sampling Electrical Insulating Liq-
electromagnetic spectrum including wavelengths from 10 to
uids
380 nm. The UV detectors of most HPLC systems operate in
the range of wavelengths from 190 to 380 nm.
This test method is under the jurisdiction of ASTM Committee D-27 on
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom-
mittee D27.03 on Analytical Tests.
Current edition approved Oct. 10, 1999. Published December 1999. Originally
published as D 5837 – 95. Last previous edition D 5837 – 95. Available from IEC, IEC Central Office, 3 rue de Varembe, P.O. Box 131,
Annual Book of ASTM Standards, Vol 10.03. CH-1211, Geneva 20, Switzerland.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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.
D 5837–99
4. Summary of Test Method 7.5 The following range of HPLC analytical conditions has
been found to be satisfactory for extracted test specimens
4.1 Furanic compounds in electrical insulating liquids are
(specific examples are given in the appendix):
extracted from a known volume of test specimen by means of
Injection Volume 15 to 30 µL
a liquid/liquid extraction or solid-phase extraction. A direct
Mobile Phase water/acetonitrile or water/methanol gradient
injection of the oil also may be used.
Flow Rate 0.5 mL/min to 1.5 mL/min
4.2 A portion of the extract or an aliquot of the oil is Column Temperature ambient to 40°C
Column 3.9 3 300 mm C18 60 to 125A, 4 to 10 µm or 4.1 3 150
introduced into an HPLC system equipped with a suitable
mm PRP-1 100 A, 5 to 10 µm
analytical column and UV detector.
Gradient see appendix
4.3 Furanic compounds in the test specimen are identified
NOTE 1—Some laboratories have found it beneficial to filter all mobile
and quantified by comparison to standards of known concen-
phase solvents with a 0.45-µm or smaller polytetrafluoroethylene or nylon
tration.
filter. Store water in containers shielded from light. Some laboratories use
50 mL of methanol added to 4 L of water to inhibit biological growth.
5. Significance and Use
7.6 The following HPLC analytical conditions have been
5.1 Furanic compounds are generated by the degradation of
found to be satisfactory for direct injection of the oil:
cellulosic materials used in the solid insulation systems of
Injection volume 20 to 30 µL
electrical equipment.
Mobile phase acetonitrile/water gradient
5.2 Furanic compounds which are oil soluble to an appre-
Flow rate, initial 0.5–1.0 mL/min
Column temperature ambient to 30°C
ciable degree will migrate into the insulating liquid.
Column WatersT Nova-Pak C18 Reversed Phased 300 3 3.9
5.3 High concentrations or unusual increases in the concen-
mm, 60A, 4 µm
trations of furanic compounds in oil may indicate cellulose
Gradient see Appendix
degradation from aging or incipient fault conditions. Testing
7.7 For direct injection, a fixed wavelength between 274
for furanic compounds may be used to complement dissolved
and281nmhasbeenfoundtoprovidethebestchromatography
gas in oil analysis as performed in accordance with Test
for all compounds of interest, except furfuryl alcohol, which is
Method D 3612.
best measured with a separate test using a wavelength between
6. Interferences 215 and 220 nm. Each furanic compound has a characteristic
maximum light absorbance occurring within the indicated
6.1 Materials used in the manufacture of the polypropylene
ranges of wavelengths. Use of variable wavelength or diode
tubes and polyethylene frits of some commercially prepared
arraydetectorsallowstheselectionofaspecificwavelengthfor
solid-phase extraction columns may interfere with the deter-
each furanic compound. Each laboratory shall select the
mination of furanic compounds, such as furfuryl alcohol and
specific wavelength to yield maximum absorbance for each
5-hydroxymethyl-2-furaldehyde.
compound as follows:
6.2 The use of acetone in any preparative or analytical step
Furanic Compound nm
will cause accelerated sample decay and may interfere with the
5-hydroxymethyl-2-furaldehyde 280 to 282
accurate determination of 5-hydroxymethyl-2- furaldehyde.
furfuryl alcohol 215 to 220
6.3 Theuseofcellulosicfilteringmediamayservetoadsorb
2-furaldehyde 272 to 280
2-acetyl furan 270 to 280
furanic compounds yielding erroneous or unreproducible re-
5-methyl-2-furaldehyde 280 to 292
sults, or both.
7.8 After the last compound of interest elutes through the
7. Apparatus
column, increase the acetonitrile or methanol to 100 % of the
7.1 High-Performance Liquid Chromatograph (HPLC)— mobile phase to remove all oil contamination remaining in the
The required analytical apparatus, an HPLC, consists of an analytical column.
injection device with sample loop, pumping system capable of 7.9 Readjust the solvent ratio of the mobile phase to the
mixing at least two solvents, reversed phase analytical column, initial conditions and allow 10 to 15 min for the column to
UV detector or detectors with the ability to operate at a come to equilibrium prior to the next injection.
minimum of two wavelengths, and a data recording device or
8. Reagents and Materials
integrator.
7.2 It is recommended that a precolumn packed with the 8.1 Acetonitrile, HPLC grade.
same material as the analytical column be used to increase 8.2 2-Acetylfuran, 99 % purity, CAS #1192-62-7.
column life and remove interferences. 8.3 Electrical Insulating Oil—Virgin oil of mineral origin.
7.3 Helium sparging of the mobile-phase solvents is recom- 8.4 2-Furaldehyde, 99 % purity, CAS #98-01-1.
mended in some cases and with some types of HPLC equip- 8.5 Furfuryl Alcohol, 99 % purity, CAS #98-00-0.
ment to displace atmospheric gases dissolved in the mobile- 8.6 Hexane, HPLC grade.
phase solvents and to prevent the evolution of air bubbles. 8.7 5-Hydroxymethyl-2-Furaldehyde, 99 % purity, CAS
7.4 The analytical apparatus may be heated several degrees #67-47-0.
Celsius above ambient if necessary to reduce variance in 8.8 Methanol, HPLC grade.
analytical results that may be caused by temperature fluctua- 8.9 5-Methyl-2-furaldehyde, 99 % purity, CAS #620-02-0.
tions. Operation at ambient temperature or at a controlled 8.10 Silica SPE Column—Solid-phase extraction column
temperature of 30 to 40°C has been found satisfactory by some filled with 500 mg of silica.
laboratories. 8.11 Toluene—HPLC grade.
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.
D 5837–99
8.12 Vacuum Manifold—Device to pull vacuum on solid- D 3487. Other dielectric liquids should conform with appli-
phase extraction column in order to pass sample and eluent cable ASTM specifications.
through SPE column.
NOTE 2—The same type of dielectric liquid should be used for standard
8.13 Volumetric Test Tube—Test tube designed to volu-
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:
9. Sampling 11.2.1 Useagraduated1-µLsyringetoinjectvolumesofthe
fivefuraniccompoundsaslistedin10.1.2into8mLoftoluene.
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 Test Method
volumetric flask. Make sure all compounds are thoroughly
D 923 or D 3613.
mixed.
10. Preparation of Extraction Standards in Solvent
11.2.2 Dilute the 8 mL of toluene containing furanic com-
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
in 10.1.1 or 10.1.2. 11.3 Gravimetric Preparation:
10.1.1 Weight Procedure—Weigh out 0.100 g 6 5% of
11.3.1 Weigh out 0.100 g 6 5 % of each of the five furanic
each of the five furanic compounds listed in this test method
compounds and record the weight to the nearest 0.1 mg.
and record the weight to the nearest 0.1 mg. Dissolve weighed
Dissolve the weighed portion in toluene and dilute volumetri-
portions into 100 mLof acetonitrile or methanol.Take 1 mLof
cally to 100 mL in toluene. Mix thoroughly so that all five
this solution and add to a clean 1-L volumetric flask. Add 199
furanic compounds are dissolved completely.
mLofeitheracetonitrileormethanol,usingthesamesolventas
11.3.2 Volumetrically dilute 1 mL of the toluene solution
was used earlier to dissolve the weighed portions of the furanic
from 11.3.1 to 1 L using electrical insulating oil of mineral
compounds. Bring the solution in the volumetric flask to 1 L
origin. This solution of furanic compounds in oil yields a
with water. Other ratios of solvent to water may be used such
concentration of about 1 mg/L (1000 µg/L) for each of the
astomatchthatoftheinitialmobilephase.Thissolutionyields
furanic compounds. Use the actual mass of each compound
a concentration of about 1 mg/L (1000 µg/L) of each of the
recorded in 11.3.1 to calculate the exact concentration in the
furanic compounds. Use the actual mass of each compound to
resulting solution. Store as described in 10.1.1.
calculate the concentration. Store in a clean, dark plastic
container. Do not store in glass.
12. Liquid/Liquid Extraction Procedure—Method A
10.1.2 Volumetric Addition—Furanic compounds that are
12.1 Measure 1 to 2 mLof the extraction solvent (methanol,
not liquid at ambient temperature should be heated to 35°C
acetonitrile, or methanol/acetonitrile) into 10 mL of the test
where all of the compounds are in a liquid state. Use a 1-µL
specimen in a test tube and cap securely. Mix using a vortex
syringe to add the indicated volumes of furanic compounds to
mixer for 3 min for acetonitrile or acetonitrile/methanol
10mLofacetonitrileormethanol.Thevolumestobeaddedare
extractions or for 1 to 5 min for methanol extractions. Other
as follows:
ratios of solvent to oil can be used as long as it is verified that
0.83 µL 6 1 % of 5-hydroxymethyl-2-furaldehyde
0.88 µL 6 1 % of furfuryl alcohol
the extraction efficiencies are unchanged.
0.86 µL 6 1 % of 2-furaldehyde
12.2 Allow the two phases to separate. The top phase is the
0.91 µL 6 1 % of 2-acetylfuran
0.90 µL 6 1 % of 5-methyl-2-furaldehyde extract,whilethebottomphaseconsistsofthenonpolarportion
of the test specimen. Separation may be enhanced by centrifu-
10.1.2.1 Thesevolumesrepresentamass
...
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