ASTM D2668-07

Standard Test Method for 2,6-<i>di-tert</i>-Butyl-<i> p</i>-Cresol and 2,6-<ital>di-tert</ital>-Butyl Phenol in Electrical Insulating Oil by Infrared Absorption

SIGNIFICANCE AND USE
The quantitative determination of 2,6-ditertiary-butyl paracresol and 2,6-ditertiary-butyl phenol in a new electrical insulating oil measures the amount of this material that has been added to the oil as protection against oxidation. In a used oil it measures the amount remaining after oxidation has reduced its concentration. The test is also suitable for manufacturing control and specification acceptance.
When an infrared spectrum is obtained of an electrical insulating oil inhibited with either of these compounds there is an increase in absorbance of the spectrum at several wavelengths (or wavenumbers). 2,6 ditertiary-butyl paracresol produces pronounced increases in absorbance at 2.72 μm (3650 cm−1), and 11.63 μm (860 cm−1). 2,6 ditertiary-butyl phenol produces pronounced increases in absorbance at 2.72 μm (3650 cm−1) and 13.42 μm (745 cm−1).
When making this test on other than a highly oxidized oil or when using a double-beam spectrophotometer, it has been found convenient to obtain the spectrum between 2.5 μm (4000 cm−1) and 2.9 μm (3450 cm−1) because the instrument is compensated for the presence of moisture and the band is not influenced by intermolecular forces (associations). However, when testing a highly oxidized oil or when using a single-beam instrument better results may be obtained if the scan is made between 10.90 μm (918 cm−1) and 14.00 μm (714 cm−1).
Increased absorption at 11.63 μm (860 cm−1) or 13.42 μm (745 cm−1) or both, will identify the inhibitor as 2,6-ditertiary-butyl paracresol or 2,6-ditertiary-butyl phenol respectively (Note 1).
Note 1—The absorbance at 745 cm−1 for 2,6-ditertiary-butyl phenol and at 860 cm−1 for 2,6-ditertiary-butyl paracresol for equal concentrations will be in the approximate ratio of 2.6 to 1.
SCOPE
1.1 This test method covers the determination of the weight percent of 2,6-ditertiary-butyl paracresol (DBPC) and 2,6-ditertiary-butyl phenol (DBP) in new or used electrical insulating oil in concentrations up to 0.5 % by measuring its absorbance at the specified wavelengths in the infrared spectrum.
1.2 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.

General Information

• Status: Historical
• Publication Date: 30-Nov-2007
• ICS: 29.040.10 - Insulating oils
• Technical Committee: D27 - Electrical Insulating Liquids and Gases
• Drafting Committee: D27.03 - Analytical Tests

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: D2668 − 07
StandardTest Method for
2,6-di-tert-Butyl-p-Cresol and 2,6-di-tert-Butyl Phenol in
1
Electrical Insulating Oil by Infrared Absorption
This standard is issued under the fixed designation D2668; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* lengths (or wavenumbers). 2,6 ditertiary-butyl paracresol pro-
duces pronounced increases in absorbance at 2.72 µm (3650
1.1 This test method covers the determination of the weight
−1 −1
cm ), and 11.63 µm (860 cm ). 2,6 ditertiary-butyl phenol
percent of 2,6-ditertiary-butyl paracresol (DBPC) and 2,6-
producespronouncedincreasesinabsorbanceat2.72µm(3650
ditertiary-butyl phenol (DBP) in new or used electrical insu-
−1 −1
cm ) and 13.42 µm (745 cm ).
lating oil in concentrations up to 0.5% by measuring its
absorbance at the specified wavelengths in the infrared spec- 3.3 When making this test on other than a highly oxidized
trum. oil or when using a double-beam spectrophotometer, it has
been found convenient to obtain the spectrum between 2.5 µm
1.2 This standard does not purport to address all of the
−1 −1
(4000cm )and2.9µm(3450cm )becausetheinstrumentis
safety concerns, if any, associated with its use. It is the
compensated for the presence of moisture and the band is not
responsibility of the user of this standard to establish appro-
influenced by intermolecular forces (associations). However,
priate safety and health practices and determine the applica-
whentestingahighlyoxidizedoilorwhenusingasingle-beam
bility of regulatory limitations prior to use.
instrument better results may be obtained if the scan is made
−1 −1
between 10.90 µm (918 cm ) and 14.00 µm (714 cm ).
2. Referenced Documents
−1
2
2.1 ASTM Standards: 3.4 Increased absorption at 11.63 µm (860 cm ) or 13.42
−1
µm (745 cm ) or both, will identify the inhibitor as 2,6-
D923Practices for Sampling Electrical Insulating Liquids
D2144Practices for Examination of Electrical Insulating ditertiary-butyl paracresol or 2,6-ditertiary-butyl phenol re-
spectively (Note 1).
Oils by Infrared Absorption
D3487Specification for Mineral Insulating Oil Used in
−1
NOTE 1—The absorbance at 745 cm for 2,6-ditertiary-butyl phenol
−1
Electrical Apparatus
and at 860 cm for 2,6-ditertiary-butyl paracresol for equal concentra-
tions will be in the approximate ratio of 2.6 to 1.
3. Significance and Use
4. Apparatus
3.1 The quantitative determination of 2,6-ditertiary-butyl
4.1 Withequipmentdescriptionreferringtocompliance,the
paracresol and 2,6-ditertiary-butyl phenol in a new electrical
equipment shall be in accordance with Section 6 of Test
insulating oil measures the amount of this material that has
Methods D2144. Accordingly, the use of Fourier-transform
been added to the oil as protection against oxidation. In a used
rapid scan infrared (FTIR) spectrophotometers is permitted by
oil it measures the amount remaining after oxidation has
reference to that test method.
reduced its concentration. The test is also suitable for manu-
facturing control and specification acceptance.
5. Sampling
3.2 When an infrared spectrum is obtained of an electrical
5.1 Obtain the sample in accordance with Practices D923.
insulating oil inhibited with either of these compounds there is
an increase in absorbance of the spectrum at several wave- 6. Calibration and Standardization
6.1 When the manufacturer of the oil is known and the base
oil is available, use it to prepare the standards. For oils of
1
This test method is under the jurisdiction of ASTM Committee D27 on
unknown origin, use base oils which meet the requirements of
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom-
mittee D27.03 on Analytical Tests.
Specification D3487. Some base oils may provide a better
Current edition approved Dec. 1, 2007. Published January 2008. Originally
match than others and therefore it is desirable to have several
´1
approved in 1967. Last previous edition approved in 2002 as D2668–02 . DOI:
available.
10.1520/D2668-07.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6.2 Prepare standards containing between 0.05 and 0.4
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
weight percent of 2,6-ditertiary-butyl paracresol or 2,6-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. ditertiary-butyl phenol dissolved in an uninhibited base oil.
*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. U
...

This document is not anASTM standard and is intended only to provide the user of anASTM 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.
e1
Designation:D 2668–02 Designation:D 2668–07
Standard Test Method for
2,6-di-tert-Butyl- p-Cresol and 2,6-di-tert-Butyl Phenol in Electrical
1
Insulating Oil by Infrared Absorption
This standard is issued under the fixed designation D 2668; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1 −1 −1
e NOTE—TheabsorbanceofDBPCandDBPwascorrectedfrom3680cm to3650cm in3.2editoriallyinNovember2005.
1. Scope*
1.1 This test method covers the determination of the weight percent of 2,6-ditertiary-butyl paracresol (DBPC) and
2,6-ditertiary-butylphenol(DBP)inneworusedelectricalinsulatingoilinconcentrationsupto0.5%bymeasuringitsabsorbance
at the specified wavelengths in the infrared spectrum.
1.2 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D923 Practices for Sampling Electrical Insulating Liquids
D2144 Practices for Examination of Electrical Insulating Oils by Infrared Absorption
D3487 Specification for Mineral Insulating Oil Used in Electrical Apparatus
3. Significance and Use
3.1 The quantitative determination of 2,6-ditertiary-butyl paracresol and 2,6-ditertiary-butyl phenol in a new electrical
insulating oil measures the amount of this material that has been added to the oil as protection against oxidation. In a used oil it
measures the amount remaining after oxidation products have has reduced its concentration. The test is also suitable for
manufacturing control and specification acceptance.
3.2When3.2 Whenaninfraredspectrumisobtainedofanelectricalinsulatingoilinhibitedwitheitherofthesecompoundsthere
is an increase in absorbance of the spectrum at several wavelengths (or wavenumbers). 2,6 ditertiary-butyl paracresol produces
−1 −1
pronounced increases in absorbance at 2.72 µm (3650 cm ), and 11.63 µm (860 cm ). 2,6 ditertiary-butyl phenol produces
−1
−1 ) and 13.42 µm (745 cm
pronounced increases in absorbance at 2.72 µm (3650 cm ) and 13.33 µm (750 cm ).
3.3 Whenmakingthistestonotherthanahighlyoxidizedoilorwhenusingadouble-beamspectrophotometer,ithasbeenfound
−1 −1
convenient to obtain the spectrum between 2.5 µm (4000 cm ) and 2.9 µm (3450 cm ) because the instrument is compensated
forthepresenceofmoistureandthebandisnotinfluencedbyintermolecularforces(associations).However,whentestingahighly
oxidized oil or when using a single-beam instrument better results may be obtained if the scan is made between 10.90 µm (918
−1 −1
cm ) and 14.00 µm (714 cm ).
−1
−1 ) or 13.42 µm (745 cm
3.4 Increased absorption at 11.63 µm (860 cm ) or 13.33 µm (750 cm ) or both, will identify the inhibitor
as 2,6-ditertiary-butyl paracresol or 2,6-ditertiary-butyl phenol respectively (Note 1).
−1 −1
NOTE 1—The absorbance at 750745 cm for 2,6-ditertiary-butyl phenol and at 860 cm for 2,6-ditertiary-butyl paracresol for equal concentrations
will be in the approximate ratio of 2.6 to 1.
4. Apparatus
4.1With4.1 With equipment description referring to compliance, the equipment shall be in accordance with Section 6 of Test
Methods D2144. Accordingly, the use of Fourier-transform rapid scan infrared (FTIR) spectrophotometers is permitted by
reference to that test method.
1
This test method is under the jurisdiction ofASTM Committee D27 on Electrical Insulating Liquids and Gases and is the direct responsibility of Subcommittee D27.03
on Analytical Tests.
Current edition approved . Published December 2002. Originally published as D2668–67. Last previous edition D2668–96.
e1
Current edition approved Dec. 1, 2007. Published January 2008. Originally approved in 1967. Last previous edition approved in 2002 as D2668–02 .
2
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,[e-mail] 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.
1

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D 2668–07
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