ASTM D1091-00
(Test Method)Standard Test Methods for Phosphorus in Lubricating Oils and Additives
Standard Test Methods for Phosphorus in Lubricating Oils and Additives
SCOPE
1.1 These test methods cover the determination of phosphorus in unused lubricating oils, 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, etc.-since all are quantitatively converted to an aqueous solution of orthophosphate ion by oxidation of the sample during the course of analysis.
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.
1.3 The values stated in acceptable metric units are to be regarded as the standard.
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An American National Standard
Designation:D1091–00
Standard Test Methods for
Phosphorus in Lubricating Oils and Additives
This standard is issued under the fixed designation D 1091; 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 adopted for use by government agencies to replace Method 5661 of Federal Test Method Standard No. 791b
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, etc.—since all are quantitatively converted to an
content is estimated to be under 2 %, and the gravimetric
aqueous solution of orthophosphate ion by oxidation of the
method is used for phosphorus contents of 2 % or over.
sample during the course of analysis.
4. Significance and Use
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4.1 Knowledge of the phosphorus content, and thus the
responsibility of the user of this standard to establish appro-
phosphorus-containing additives, in a lubricating oil or addi-
priate safety and health practices and determine the applica-
tive can be used to predict performance characteristics. This
bility of regulatory limitations prior to use.
test method is suitable for most applications requiring the
1.3 The values stated in SI units are to be regarded as the
determination of phosphorus.
standard.
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
D 1193 Specification for Reagent Water
all reagents conform to the specifications of the Committee on
D 3231 Test Method for Phosphorus in Gasoline
Analytical Reagents of the American Chemical Society where
D 4057 Practice for Manual Sampling of Petroleum and
such specifications are available. Other grades may be used,
Petroleum Products
provided it is first ascertained that the reagent is of sufficiently
D 4177 Practice for Automatic Sampling of Petroleum and
high purity to permit its use without lessening the accuracy of
Petroleum Products
the determination.
D 6299 Practice for Applying Statistical Quality Assurance
5.2 Purity of Water—Unless otherwise indicated, references
Techniques to Evaluate Analytical Measurement System
to water shall be understood to mean reagent water as defined
Performance
by Type II or Type III of Specification D 1193.
3. Summary of Test Method
6. Sampling
3.1 Organic material in the sample is removed and the
6.1 Obtain samples in accordance with the instructions in
phosphorus is converted to phosphate ion by oxidation with
Practices D 4057 or D 4177.
These test methods are under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and are the responsibility of Subcommittee
D02.03 on Elemental Analysis. Reagent Chemicals, American Chemical Society Specifications, American
Current edition approved April 10, 2000. Published July 2000. Originally Chemical Society, Washington, D.C. For suggestions on the testing of reagents not
published as D1091 – 50 T. Last previous edition D1091 – 95. listed by the American Chemical Society, see Analar Standards for Laboratory
Annual Book of ASTM Standards, Vol 11.01. Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Annual Book of ASTM Standards, Vol 05.02. and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
Annual Book of ASTM Standards, Vol 05.03. 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
TABLE 1 Sample Size
6.2 Take care that the test specimen is thoroughly represen-
tative of the material to be tested and that the portion of the Approximate Weight Precision of Weighing,
Phosphorus Content, %
of Sample, g plus or minus, g
sample is thoroughly representative of the test unit.
Photometric (Molybdivanado) Method
0.002 to 0.2 2 0.004
OXIDATION OF THE SAMPLE
0.2 to 2 0.2 0.0004
Gravimetric Method
2to5 2 0.004
7. Scope
5 to 10 1 0.003
7.1 This test method covers a procedure for removal of
10 to 15 0.7 0.002
15 to 25 0.4 0.001
organic material and subsequent conversion of phosphorus to
phosphateioninsamplesofunusedlubricatingoils,lubricating
oil additives, and their concentrates.
8. Summary of Test Method precautions in handling. The usual precautions of cleanliness,
careful manipulation, and avoidance of contamination should
8.1 Organic material in the sample is destroyed and the
bescrupulouslyobserved;also,allglasswareshouldbecleaned
phosphorus is converted to phosphate ion by oxidation with
before use, with cleaning acid or by some procedure that does
sulfuric acid, nitric acid, and hydrogen peroxide. The residual
not involve use of commercial detergents. These compounds
hydrogen peroxide is removed by diluting with water and
often contain alkali phosphates, which are strongly absorbed
evaporating several times to dense white fumes.
by glass surfaces and are not removed by ordinary rinsing. It is
9. Apparatus desirable to segregate a special stock of glassware for use only
in the determination of phosphorus.
9.1 Digestion Flasks, Kjeldahl flasks, 300 mL, ground-glass
stoppered.
NOTE 1—The volume occupied by the glass bead (0.1 mL) can be
9.2 Digestion Rack—A digestion rack constructed to hold ignored for ordinary work. Excessive bumping is encountered occasion-
ally in the digestion of some organic phosphorus compounds. This
one or more 300-mL Kjeldahl flasks at an angle of approxi-
bumping can be minimized by using a glass bead. Some difficulty can be
mately 45° in such a fashion that direct heat is applied only to
experienced when using commercial boiling aids in obtaining a solution
the bottom of the flask and such that the body and neck of the
clear enough for photometric measurement of phosphorus (see Sections
flask are insulated from the source of heat. Approximately
12-18) even after centrifuging, due to the attrition of these boiling aids
three fourths of the neck of the flask should be cooled by air at
under the vigorous digestion procedure.
atmospheric temperature, preferably by directing an air stream
11.3 Make a blank determination following the same pro-
against the neck of the flask. A bunsen flame or high capacity
cedureandusingthesameamountsofallreagentsandasimilar
electric heater are suitable heat sources.
size sample of phosphorus-free white oil. This blank is for use
in the photometric method (see Sections 12-18).
10. Reagents
11.4 Place the flask on the digestion rack under a hood and
10.1 Hydrogen Peroxide (30 %), concentrated hydrogen
warm gently with a micro burner until the test specimen is
peroxide (H O)(Warning—Concentrated solutions are
2 2
charred, while cooling the neck of the flask, preferably by use
highly toxic and strong oxidants.) containing no more than
of an air stream (see Note 2). Continue heating until dense
0.0002 % phosphorus.
white fumes appear (see Note 3). While boiling, continuously
10.2 Nitric Acid (sp gr 1.42), concentrated nitric acid
add 1 mL of HNO dropwise (see Note 4) to oxidize the
(HNO ).
organic material. When the HNO has boiled off and dense
10.3 Sulfuric Acid (sp gr 1.84), concentrated sulfuric acid
white fumes reappear, repeat the treatment with an additional 1
(H SO ).
2 4
mL of HNO (see Note 5). Continue the addition of HNO in
3 3
10.4 White Oil, phosphorus-free.
1-mL increments until the digestion mixture is no darker than
10.5 Quality Control (QC) Samples, preferably, portions of
a straw color, indicating that almost all the organic matter has
one or more liquid petroleum materials that are stable and
been oxidized.
representative of the samples of interest. These QC samples
NOTE 2—The amount of air used to cool the neck of the flask will at
can be used to check the validity of the testing process, as
times have to be reduced or even shut off to allow vapors and fumes to
described in Section 26.
leave the flask and to allow sample to come to dense white fumes.
However, this should not be done until the test specimen is in a
11. Procedure
well-decomposedstate;theairstreamshouldbeturnedonagaineachtime
11.1 Weigh out a portion of the material to be analyzed, in
before the addition of the HNO or H O (see 11.4).
3 2 2
accordance with Table 1, into a 300-mL Kjeldahl flask. Any
NOTE 3—Excessive evaporation of H SO should be avoided to mini-
2 4
convenient method of transferring the test specimen may be mize any loss of phosphorus that may occur. Care should be exercised to
avoid heating above the liquid level. Since there is some indication that
used as long as care is taken to avoid getting the test specimen
with test specimens containing inorganic compounds (that is, barium or
on the neck of the flask (see Note 1).Add H SO (3 mLfor the
2 4
lead salts) there can be losses of phosphorus due to sintering or fusion of
photometric procedure, or 10 mL for the gravimetric proce-
thephosphateandsulfatetotheglass,itiswelltoexaminethedriedvessel
dure) and a 6-mm glass bead (see Note 2), and swirl the flask
after use to detect any opaque film of fused material.
to mix the contents.
NOTE 4—Unless the HNO is added dropwise, it can force excessive
11.2 To obtain satisfactory accuracy with the small amounts
amounts of vapor from the flask and lead to loss of phosphorus containing
of phosphorus involved, it is necessary to take extensive fumes.
D1091–00
NOTE 5—To minimize the loss of H SO in the digestion process, it is
1, 2, and 5-cm cells, and a supply of these should be available.
2 4
advisable not to prolong the dense white fumes stage between addition of
Other instruments such as photoelectric filter photometers may
HNO .
also be used.
11.5 Cool the flask slightly and add 10 drops (0.5 mL) of
NOTE 7—While not as desirable as photometers, visual color compara-
H O . Heat until dense white fumes appear, and while boiling,
2 2 tors can also be used, if necessary.
cautiously add 1 mL of HNO dropwise. When the HNO has
3 3
boiledoffanddensewhitefumesreappear,repeatthetreatment 15. Reagents
with H O and HNO until the digestion mixture is colorless,
2 2 3
15.1 Ammonium Molybdate Solution—Dissolve 50 g of
atwhichtimetheorganicmaterialwillbecompletelyoxidized.
ammonium molybdate (NH ) Mo O ·4H O) in warm water
4 6 7 24 2
Four treatments will usually suffice. The total amount of H O
2 2
and dilute to 1 L. Filter before using.
used should be noted, and the same amount used for each test
15.2 Ammonium Vanadate Solution—Dissolve 2.5 g of
specimen and the blank.
ammonium vanadate (NH VO ) in 500 mL of hot water, add
4 3
11.6 When oxidation is complete, allow the flask to cool,
20mLofconcentratednitricacid(HNO relativedensity1.42),
wash down the mouth and neck with a minimum amount of
and dilute to 1 L.
water (5 mL), and mix the contents. Return the flask to the
15.3 Phosphate, Standard Solution (1 mL = 0.1 mg P)—
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
16.1 Introduce 0, 0.4, 0.8, 1.6, 2.4, 4.0, 4.8, 8.0, 16, 24, and
12. Scope
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
2 4
phorus in concentrations of less than two mass % (see Note 6), 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
mixing between additions. Dilute to 100 mL, close with a
NOTE 6—For phosphorus concentrations greater than or equal to two
ground-glass stopper, and mix thoroughly. Allow to stand at
mass %, see Sections 19-25.
least 45 min but no longer than 60 min to develop the color.
16.2 Usingthe1-cmcellandwiththewavelengthsetat460
13. Summary of Test Method
nm, adjust the photometer to read 100.0 % transmittance with
13.1 Afteroxidationoforganicmaterialinthetestspecimen
the zero phosphate (reagent blank) standard.Although absorp-
and quantitative conversion of the phosphorus to phosphate
tion cells are usually very closely matched, for best work it is
ion, the acidity of the digestion mixture is adjusted and the
recommended that two cells be used and that one be reserved
mixture diluted to suitable volume. Solutions of ammonium
fortheblankandtheotherforthestandardorsamplesolutions.
vanadate and ammonium molybdate are added in the order
Obtain transmittance measurements on solutions containing
named. The addition of the molybdate solution to the acid
0.4, 0.8, 1.6, 2.4, and 3.2 mg of phosphorus. These standards
vanadate-phosphate mixture results in the formation of a
should give measurements falling between 90 and 20 %
heteropoly acid, molybdivanadophosphoric acid, which is
respectiv
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