ASTM D1091-00(2005)
(Test Method)Standard Test Methods for Phosphorus in Lubricating Oils and Additives
Standard Test Methods for Phosphorus in Lubricating Oils and Additives
SIGNIFICANCE AND USE
Knowledge of the phosphorus content, and thus the phosphorus-containing additives, in a lubricating oil or additive can be used to predict performance characteristics. This test method is suitable for most applications requiring the determination of phosphorus.
SCOPE
1.1 These test methods cover the determination of phosphorus in unused lubricating oils and lubricating oil additives and their concentrates. The test methods are not restricted with respect to the type of phosphorus compounds that may be present-for example, trivalent or pentavalent phosphorus compounds, phosphines, phosphates, phosphonates, phosphorus sulfides, and so forth-since all are quantitatively converted to an aqueous solution of orthophosphate ion by oxidation of the sample during the course of analysis.
1.2 The values stated in SI units are to be regarded as the standard.
1.3This 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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Designation:D1091–00 (Reapproved 2005)
Standard Test Methods for
Phosphorus in Lubricating Oils and Additives
This standard is issued under the fixed designation D1091; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope* sulfuric acid, nitric acid, and hydrogen peroxide. One of two
procedures is then followed:
1.1 These test methods cover the determination of phospho-
Sections
rus in unused lubricating oils and lubricating oil additives and
Photometric (Molydivanado) Method 7-18
their concentrates. The test methods are not restricted with
Gravimetric Method 7-11
respect to the type of phosphorus compounds that may be
and
19-25
present—for example, trivalent or pentavalent phosphorus
compounds, phosphines, phosphates, phosphonates, phospho-
3.2 The photometric method is used where the phosphorus
rus sulfides, and so forth—since all are quantitatively con-
content is estimated to be under 2 %, and the gravimetric
verted to an aqueous solution of orthophosphate ion by
method is used for phosphorus contents of 2 % or over.
oxidation of the sample during the course of analysis.
4. Significance and Use
1.2 The values stated in SI units are to be regarded as the
standard.
4.1 Knowledge of the phosphorus content, and thus the
1.3 This standard does not purport to address all of the
phosphorus-containing additives, in a lubricating oil or addi-
safety concerns, if any, associated with its use. It is the
tive can be used to predict performance characteristics. This
responsibility of the user of this standard to establish appro-
test method is suitable for most applications requiring the
priate safety and health practices and determine the applica-
determination of phosphorus.
bility of regulatory limitations prior to use.
5. Purity of Reagents
2. Referenced Documents
5.1 Purity of Reagents—Reagent grade chemicals shall be
2.1 ASTM Standards:
used in all tests. Unless otherwise indicated, it is intended that
D1193 Specification for Reagent Water
all reagents conform to the specifications of the Committee on
D4057 Practice for Manual Sampling of Petroleum and
Analytical Reagents of the American Chemical Society where
Petroleum Products
such specifications are available. Other grades may be used,
D4177 Practice for Automatic Sampling of Petroleum and
provided it is first ascertained that the reagent is of sufficiently
Petroleum Products
high purity to permit its use without lessening the accuracy of
D6299 Practice for Applying Statistical Quality Assurance
the determination.
and Control Charting Techniques to Evaluate Analytical
5.2 Purity of Water—Unless otherwise indicated, references
Measurement System Performance
to water shall be understood to mean reagent water as defined
by Type II or Type III of Specification D1193.
3. Summary of Test Method
6. Sampling
3.1 Organic material in the sample is removed and the
phosphorus is converted to phosphate ion by oxidation with
6.1 Obtain samples in accordance with the instructions in
Practices D4057 or D4177.
6.2 Take care that the test specimen is thoroughly represen-
These test methods are under the jurisdiction of ASTM Committee D02 on
tative of the material to be tested and that the portion of the
Petroleum Products and Lubricants and are the responsibility of Subcommittee
sample is thoroughly representative of the test unit.
D02.03 on Elemental Analysis.
Current edition approved May 1, 2005. Published May 2005. Originally
approved in 1950. Last previous edition approved in 2000 as D1091 – 00.
This test method has been adopted for use by government agencies to replace
Method 5661 of Federal Test Method Standard No. 791b DOI: 10.1520/D1091- Reagent Chemicals, American Chemical Society Specifications , American
00R05. Chemical Society, Washington, D.C. For suggestions on the testing of reagents not
For referenced ASTM standards, visit the ASTM website, www.astm.org, or listed by the American Chemical Society, see Analar Standards for Laboratory
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Standards volume information, refer to the standard’s Document Summary page on and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
the ASTM website. MD.
*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.
D1091–00 (2005)
TABLE 1 Sample Size
used as long as care is taken to avoid getting the test specimen
Approximate Weight Precision of Weighing, on the neck of the flask (see Note 1).Add H SO (3 mLfor the
2 4
Phosphorus Content, %
of Sample, g plus or minus, g
photometric procedure, or 10 mL for the gravimetric proce-
Photometric (Molybdivanado) Method
dure) and a 6-mm glass bead (see Note 2), and swirl the flask
0.002 to 0.2 2 0.004
0.2 to 2 0.2 0.0004 to mix the contents.
Gravimetric Method
11.2 To obtain satisfactory accuracy with the small amounts
2to5 2 0.004
of phosphorus involved, it is necessary to take extensive
5 to 10 1 0.003
10 to 15 0.7 0.002
precautions in handling. The usual precautions of cleanliness,
15 to 25 0.4 0.001
careful manipulation, and avoidance of contamination should
bescrupulouslyobserved;also,allglasswareshouldbecleaned
before use, with cleaning acid or by some procedure that does
OXIDATION OF THE SAMPLE
not involve use of commercial detergents. These compounds
often contain alkali phosphates, which are strongly absorbed
7. Scope
by glass surfaces and are not removed by ordinary rinsing. It is
7.1 This test method covers a procedure for removal of
desirable to segregate a special stock of glassware for use only
organic material and subsequent conversion of phosphorus to
in the determination of phosphorus.
phosphateioninsamplesofunusedlubricatingoils,lubricating
NOTE 1—The volume occupied by the glass bead (0.1 mL) can be
oil additives, and their concentrates.
ignored for ordinary work. Excessive bumping is encountered occasion-
ally in the digestion of some organic phosphorus compounds. This
8. Summary of Test Method
bumping can be minimized by using a glass bead. Some difficulty can be
8.1 Organic material in the sample is destroyed and the experienced when using commercial boiling aids in obtaining a solution
clear enough for photometric measurement of phosphorus (see Sections
phosphorus is converted to phosphate ion by oxidation with
12-18) even after centrifuging, due to the attrition of these boiling aids
sulfuric acid, nitric acid, and hydrogen peroxide. The residual
under the vigorous digestion procedure.
hydrogen peroxide is removed by diluting with water and
11.3 Make a blank determination following the same pro-
evaporating several times to dense white fumes.
cedureandusingthesameamountsofallreagentsandasimilar
9. Apparatus
size sample of phosphorus-free white oil. This blank is for use
in the photometric method (see Sections 12-18).
9.1 Digestion Flasks, Kjeldahl flasks, 300 mL, ground-glass
11.4 Place the flask on the digestion rack under a hood and
stoppered.
warm gently with a micro burner until the test specimen is
9.2 Digestion Rack—A digestion rack constructed to hold
charred, while cooling the neck of the flask, preferably by use
one or more 300-mL Kjeldahl flasks at an angle of approxi-
of an air stream (see Note 2). Continue heating until dense
mately 45° in such a fashion that direct heat is applied only to
white fumes appear (see Note 3). While boiling, continuously
the bottom of the flask and such that the body and neck of the
add 1 mL of HNO dropwise (see Note 4) to oxidize the
flask are insulated from the source of heat. Approximately 3
organic material. When the HNO has boiled off and dense
three-fourths of the neck of the flask should be cooled by air at
white fumes reappear, repeat the treatment with an additional 1
atmospheric temperature, preferably by directing an air stream
mL of HNO (see Note 5). Continue the addition of HNO in
against the neck of the flask. A Bunsen flame or high capacity
3 3
1-mL increments until the digestion mixture is no darker than
electric heater are suitable heat sources.
a straw color, indicating that almost all the organic matter has
10. Reagents
been oxidized.
10.1 Hydrogen Peroxide (30 %), concentrated hydrogen
NOTE 2—The amount of air used to cool the neck of the flask will at
peroxide (H O)(Warning—Concentrated solutions are times have to be reduced or even shut off to allow vapors and fumes to
2 2
leave the flask and to allow sample to come to dense white fumes.
highly toxic and strong oxidants.) containing no more than
However, this should not be done until the test specimen is in a
0.0002 % phosphorus.
well-decomposedstate;theairstreamshouldbeturnedonagaineachtime
10.2 Nitric Acid (sp gr 1.42), concentrated nitric acid
before the addition of the HNO or H O (see 11.4).
3 2 2
(HNO ).
NOTE 3—Excessive evaporation of H SO should be avoided to mini-
2 4
10.3 Sulfuric Acid (sp gr 1.84), concentrated sulfuric acid
mize any loss of phosphorus that may occur. Care should be exercised to
(H SO ).
avoid heating above the liquid level. Since there is some indication that
2 4
10.4 White Oil, phosphorus-free. with test specimens containing inorganic compounds (that is, barium or
lead salts) there can be losses of phosphorus due to sintering or fusion of
10.5 Quality Control (QC) Samples, preferably, portions of
thephosphateandsulfatetotheglass,itiswelltoexaminethedriedvessel
one or more liquid petroleum materials that are stable and
after use to detect any opaque film of fused material.
representative of the samples of interest. These QC samples
NOTE 4—Unless the HNO is added dropwise, it can force excessive
can be used to check the validity of the testing process, as
amounts of vapor from the flask and lead to loss of phosphorus containing
described in Section 26.
fumes.
NOTE 5—To minimize the loss of H SO in the digestion process, it is
2 4
11. Procedure
advisable not to prolong the dense white fumes stage between addition of
HNO .
11.1 Weigh out a portion of the material to be analyzed, in 3
accordance with Table 1, into a 300-mL Kjeldahl flask. Any 11.5 Cool the flask slightly and add 10 drops (0.5 mL) of
convenient method of transferring the test specimen may be H O . Heat until dense white fumes appear, and while boiling,
2 2
D1091–00 (2005)
cautiously add 1 mL of HNO dropwise. When the HNO has 15. Reagents
3 3
boiledoffanddensewhitefumesreappear,repeatthetreatment
15.1 Ammonium Molybdate Solution—Dissolve 50 g of
with H O and HNO until the digestion mixture is colorless,
2 2 3
ammonium molybdate (NH ) Mo O ·4H O) in warm water
4 6 7 24 2
atwhichtimetheorganicmaterialwillbecompletelyoxidized.
and dilute to 1 L. Filter before using.
Four treatments will usually suffice. The total amount of H O
2 2
15.2 Ammonium Vanadate Solution—Dissolve 2.5 g of
used should be noted, and the same amount used for each test
ammonium vanadate (NH VO ) in 500 mL of hot water, add
specimen and the blank. 4 3
20mLofconcentratednitricacid(HNO relativedensity1.42),
11.6 When oxidation is complete, allow the flask to cool,
and dilute to 1 L.
wash down the mouth and neck with a minimum amount of
15.3 Phosphate, Standard Solution (1 mL = 0.1 mg P)—
water (5 mL), and mix the contents. Return the flask to the
digestion rack and continue heating to the appearance of dense Dissolve 0.4393 g of potassium dihydrogen phosphate (KH -
white fumes. Repeat the process of the addition of water and
PO ) in water and dilute to 1 L. For best work, the salt should
heating to dense fumes several times. This will remove all
be twice recrystallized and vacuum-dried before use.
traces of H O.(Warning—Use extreme care in fuming, in
2 2
15.4 Sulfuric Acid (relative density 1.84), concentrated sul-
accordance with 11.5, to remove all traces of H O so that no
2 2
furic acid (H SO ).
2 4
color interference will be experienced when phosphorus is to
15.5 QC Samples, preferably, portions of one or more liquid
be determined photometrically, as described in Sections 12-
petroleum materials that are stable and representative of the
18.)
samplesofinterest.TheseQCsamplescanbeusedtocheckthe
validity of the testing process, as described in Section 26.
PHOTOMETRIC (MOLYBDIVANADO)
METHOD
16. Calibration and Standardization
12. Scope
16.1 Introduce 0, 0.4, 0.8, 1.6, 2.4, 4.0, 4.8, 8.0, 16, 24, and
32 mL of standard phosphate solution into 100-mL ground-
12.1 This test method covers determination of total phos-
glass-stoppered volumetric flasks.Add sufficient H SO of any
phorus in concentrations of less than two mass % (see Note 6),
2 4
convenient concentration such that the final acid concentration
calculatedonthebasisoftheoriginaltestspecimen,insamples
after dilution to 100 mL will be 0.5 N. Dilute to 55 to 60 mL,
treated by the acid-oxidation procedure described in Sections
and add 10 mL of ammonium vanadate solution and ammo-
7-11.
nium molybdate solution, in the order named, with adequate
NOTE 6—For phosphorus concentrations greater than or equal to two
mixing between additions. Dilute to 100 mL, close with a
mass %, see Sections 19-25.
ground-glass stopper, and mix thoroughly. Allow to stand at
least 45 min but no longer than 60 min to develop the color.
13. Summary of Test Method
16.2 Usingthe1-cmcellandwiththewavelengthsetat460
13.1 Afteroxidationoforganicmaterialinthetestspecimen
nm, adjust the photometer to read 100.0 % transmittance with
and quantitative conversion of the phosphorus to phosphate
the zero phosphate (reagent blank) standard.Although absorp-
ion, the acidity of the digestion mixture is adjusted and the
tion cells are usually very closely matched, for best work it is
mixture diluted to suitable volume. Solutions of ammonium
recommended that two cells be used and that one be reserved
vanadate and ammonium molybdate are added in the order
fortheblankandtheotherforthestandardorsamplesolutions.
named. The addition of the molybdate solution to the acid
Obtain transmittance measurements on solutions containing
vanadate-phosphate mixture results in the formation of a
heteropoly acid, molybdivanadophosphoric acid, which is 0.4, 0.8, 1.6, 2.4, and 3.2 mg of phosphorus. These standards
should give measurements falling between 90 and 20 %
yellow in color. Although the exact composition of mo
...
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