ASTM D2896-01

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An American National Standard
Designation: D 2896 – 01
Designation: 276/95
Standard Test Method for
Base Number of Petroleum Products by Potentiometric
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Perchloric Acid Titration
This standard is issued under the fixed designation D 2896; 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.
This test method has been approved by the sponsoring committees and accepted by the cooperating societies in accordance with
established procedures.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 2. Referenced Documents
1.1 This test method covers the determination of basic 2.1 ASTM Standards:
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constituents in petroleum products by titration with perchloric D 1193 Specification for Reagent Water
acid in glacial acetic acid.
3. Terminology
1.2 Procedures A and B use different titration solvent
3.1 Definitions of Terms Specific to This Standard:
volumes and sample weights.
3.1.1 base number—the quantity of perchloric acid ex-
NOTE 1—A round robin on a series of new and used oils and additive
pressed in terms of the equivalent number of milligrams of
concentrates has shown that the two procedures give statistically equiva-
potassium hydroxide that are required to titrate1gofthe
lent results.
sample dissolved in the specified solvent to a well-defined
1.3 Appendix X2 provides the use of an alternative solvent
inflection point as specified in this test method.
system which eliminates the use of chlorobenzene in this test
method. The use of the alternative solvent gives statistically
4. Summary of Test Method
equivalent results; however, the precision is worse. Paragraph
4.1 The sample is dissolved in an essentially anhydrous
X2.5.5 provides guidance when comparing results using the
mixture of chlorobenzene and glacial acetic acid and titrated
two different solvents.
with a solution of perchloric acid in glacial acetic acid using
1.4 The constituents that may be considered to have basic
potentiometric titrimeter. A glass indicating electrode and a
characteristics include organic and inorganic bases, amino
calomel reference electrode are used, the latter being connected
compounds, salts of weak acids (soaps), basic salts of polya-
with the sample solution by means of a salt bridge. The meter
cidic bases, and salts of heavy metals.
readings are plotted against the respective volumes of titrating
NOTE 2—This test method is applicable to both fresh oils and used oils solution, and the end point is taken at the inflection in the
as described in Sections 16, 17, and 19 and in the Appendix X1.
resulting curve.
4.2 Procedure A uses 120 mL of titration solvent. Procedure
1.5 This test method can be used to determine base number
B uses 60 mL of titration solvent. In addition, the two
>300 mg KOH/g. However, the precision statement in Section
procedures use different equations for the calculation of appro-
19 has been obtained only on base number #300 mg KOH/g.
priate sample weights. Since many portions of the test method
1.6 This standard does not purport to address all of the
are identical for procedures A and B, only the unique sections
safety concerns, if any, associated with its use. It is the
will be described separately for the two versions of the test
responsibility of the user of this standard to establish appro-
method.
priate safety and health practices and determine the applica-
4.3 Occasionally certain used oils give no inflection in the
bility of regulatory limitations prior to use. For specific hazard
forward titration mode, in which case a back titration modifi-
statements, see Section 7, Section 10, and X2.2.
cation with sodium acetate titrant is employed.
1 5. Significance and Use
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
5.1 New and used petroleum products can contain basic
D02.06 on Analysis of Lubricants.
Current edition approved Nov. 10, 2001. Published November 2001. Originally
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published as D 2896 – 70 T. Last previous edition D 2896 – 98. Annual Book of ASTM Standards, Vol 11.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D 2896
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constituents that are present as additives. The relative amounts where such specifications are available. Other grades may be
of these materials can be determined by titration with acids. used, provided it is first ascertained that the reagent is of
The base number is a measure of the amount of basic substan
...