ASTM D4768-03

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Designation:D4768–03
Standard Test Method for
Analysis of 2,6-Ditertiary-Butyl Para-Cresol and 2,6-
Ditertiary-Butyl Phenol in Insulating Liquids by Gas
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Chromatography
This standard is issued under the fixed designation D4768; 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 4. Significance and Use
1.1 This test method covers the determination by gas 4.1 Innewelectricalinsulatingoil,thistestmethodprovides
chromatography of 2,6-ditertiary-butyl para-cresol and 2,6- a quantitative measure of the amounts of 2,6-ditertiary-butyl
ditertiary-butyl phenol in new and used insulating liquids at para-cresol and 2,6-ditertiary-butyl phenol that have been
concentrations up to 0.5 %. It includes the determination in added to the oil. In a used oil, the test measures the amount of
Type I and II insulating mineral oils as specified in Specifica- these inhibitors remaining in the oil. This test method is
tion D3487, but has also been used to measure these inhibitors suitable for manufacturing control, specification acceptance,
in other insulating liquids, such as esters and high fire-point and service evaluation.
hydrocarbons. 4.2 This test method is used to separate, identify, and
1.2 This standard does not purport to address all of the quantify the inhibitors with minimal interference and matrix
safety concerns, if any, associated with its use. It is the effects.
responsibility of the user of this standard to establish appro- 4.3 This test method has also been used successfully to
priate safety and health practices and determine the applica- determine the inhibitor concentrations in other insulating
bility of regulatory limitations prior to use. liquids such as esters and high-temperature hydrocarbons.
2. Referenced Documents 5. Apparatus
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2.1 ASTM Standards: 5.1 Gas Chromatograph, equipped with oven temperature
D923 Practices for Sampling Electrical Insulating Liquids control constant to 1°C and with heated injector port.
D3487 Specification for Mineral Insulating Oil Used in 5.1.1 Means to Record the Chromatogram, such as a pen
Electrical Apparatus recorder or a digital integrator to determine peak areas, is
D5222 Specification for High Fire-Point Mineral Electrical recommended. An automated sample injector may be used.
Insulating Oils 5.2 Flame Ionization Detector, with appropriate hydrogen/
E260 Practice for Packed Column Gas Chromatography air gas flows, is preferred over a thermal conductivity detector
to provide maximum sensitivity.
3. Summary of Test Method
5.3 Column, a suitable stainless steel or glass column
3.1 The test specimen is placed onto a column containing packed with a nonpolar silicone on an appropriate support.
activated alumina and extracted to remove interfering sub-
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NOTE 1—A3 % OV-1 on 100/120 Mesh Supelcoport, 1.83 m (6 ft)
stances. The inhibitors are then eluted from the column with
long, 3.2 mm (0.125 in.) in outside diameter has been used successfully.
suitable solvent and analyzed by gas chromatography. The
5.3.1 Condition columns in accordance with manufacturer’s
inhibitor type and quantity are determined by comparison of
recommendations. Disconnect columns from detector prior to
each component with a working standard tested under similar
conditioning and reconnect after conditioning.
conditions.
5.4 Precision Syringe, glass, 10.0 µL.
5.5 Volumetric Glassware, appropriate for making dilutions.
5.6 Pipets, Pasteur, disposable, 146 by 7.5 mm.
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This test method is under the jurisdiction of ASTM Committee D27 on
5.7 Analytical Balance.
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom-
mittee D27.03 on Analytical Tests. 5.8 Automatic Pipetter, 1 mL calibrated, adjustable.
Current edition approved March 10, 2003. Published May 2003. Originally
5.9 Oven, capable of maintaining a temperature of 275 6
approved in 1988 as D4768 – 88. Last previous edition approved in 1996 as
5°C for conditioning extraction columns.
D4768 – 96. DOI: 10.1520/D4768-03.
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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
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Standards volume information, refer to the standard’s Document Summary page on Registered trademark of Ohio Valley Specialty Co.
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the ASTM website. Registered trademark of Supelco, Inc.
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D4768–03
5.10 Desiccator. 7.3.4 Calculate the extraction efficiency for both DBP and
DBPC as foll
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