ASTM D4927-96
(Test Method)Standard Test Methods for Elemental Analysis of Lubricant and Additive Components—Barium, Calcium, Phosphorus, Sulfur, and Zinc by Wavelength-Dispersive X-Ray Fluorescence Spectroscopy
Standard Test Methods for Elemental Analysis of Lubricant and Additive Components—Barium, Calcium, Phosphorus, Sulfur, and Zinc by Wavelength-Dispersive X-Ray Fluorescence Spectroscopy
SCOPE
1.1 These test methods cover the determination of barium, calcium, phosphorus, sulfur, and zinc in unused lubricating oils at element concentration ranges from 0.03 to 1.0 mass % (0.01 to 2.0 mass % for sulfur). The range can be extended to higher concentrations by dilution of sample specimens. Additives can also be determined after dilution. Two different methods are presented in these test methods.
1.2 Test Method A (Internal Standard Procedure)—Internal standards are used to compensate for interelement effects of X-ray excitation and fluorescence (see Sections 1-12, and 19).
1.3 Test Method B (Mathematical Correction Procedure)—The measured X-ray fluorescence intensity for a given element is mathematically corrected for potential interference from other elements present in the sample (see Sections 1-6, and 13-19).
1.4 The preferred concentration units are mass percent barium, calcium, phosphorus, sulfur, or zinc.
1.5 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.
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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
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Designation: D 4927 – 96 An American National Standard
Standard Test Methods for
Elemental Analysis of Lubricant and Additive Components—
Barium, Calcium, Phosphorus, Sulfur, and Zinc by
Wavelength-Dispersive X-Ray Fluorescence Spectroscopy
This standard is issued under the fixed designation D 4927; 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 standard has been approved for use by agencies of the Department of Defense.
1. Scope compensate for the potential interelement effects.
2.2.1 Barium, Calcium, Phosphorus, and Zinc—A sample
1.1 These test methods cover the determination of barium,
specimen that has been blended with a single internal standard
calcium, phosphorus, sulfur, and zinc in unused lubricating oils
solution (containing tin or titanium for barium and calcium,
at element concentration ranges from 0.03 to 1.0 mass % (0.01
zirconium for phosphorus, and nickel for zinc) is poured into
to 2.0 mass % for sulfur). The range can be extended to higher
an X-ray cell. Total net counts (peak intensity—background)
concentrations by dilution of sample specimens. Additives can
for each element and its respective internal standard are
also be determined after dilution. Two different methods are
collected at their appropriate wavelengths. The ratios between
presented in these test methods.
elemental and internal standard counts are calculated and
1.2 Test Method A (Internal Standard Procedure)—Internal
converted into barium, calcium, phosphorus, or zinc concen-
standards are used to compensate for interelement effects of
trations, or a combination thereof, from calibration curves.
X-ray excitation and fluorescence (see Sections 1-11, and 16).
2.2.2 Sulfur—A sample specimen is mixed with a lead
1.3 Test Method B (Mathematical Correction Procedure)—
internal standard solution and analyzed as described in 2.2.1.
The measured X-ray fluorescence intensity for a given element
2.3 Test Method B (Mathematical Correction Procedure)—
is mathematically corrected for potential interference from
The measured intensity for a given element is mathematically
other elements present in the sample (see Sections 1-6, and
corrected for the interference from other elements in the
12-16).
sample specimen. This requires that intensities from all ele-
1.4 The preferred concentration units are mass percent
ments in the specimen be obtained.
barium, calcium, phosphorus, sulfur, or zinc.
2.3.1 The sample specimen is placed in the X-ray beam and
1.5 This standard does not purport to address all of the
the intensities of the fluorescence lines of barium, calcium,
safety concerns, if any, associated with its use. It is the
phosphorus, sulfur, and zinc are measured. A similar measure-
responsibility of the user of this standard to establish appro-
ment is made away from the fluorescence lines in order to
priate safety and health practices and determine the applica-
obtain a background correction. Concentrations of the elements
bility of regulatory limitations prior to use.
of interest are determined by comparison of net signals against
2. Summary of the Test Methods appropriate interelement correction factors developed from
responses of calibration standards.
2.1 A sample specimen is placed in the X-ray beam and the
2.3.2 The X-ray fluorescence spectrometer is initially cali-
intensity of the appropriate fluorescence lines of barium,
brated with a suite of standards in order to determine by
calcium, phosphorus, sulfur, and zinc are measured. Instrument
regression analysis, interelement correction factors and instru-
response factors related to the concentration of standards
ment response factors.
enable the determination of the concentration of elements in
2.3.3 Subsequent calibration is achieved using a smaller
the tested sample specimens. Enhancement or depression of the
number of standards since only the instrument response factors
X-ray fluorescence of a given element by an interfering
need to be redetermined. One of these standards (or an optional
element in the sample may occur. Two test methods (A and B)
synthetic pellet) can be used to monitor instrumental drift when
are described for compensating any interference effect.
performing a high volume of analyses.
2.2 Test Method A (Internal Standard Procedure)—Internal
2.4 Additives and additive packages can be determined after
standards are used with the standards and sample specimens to
dilution with base oil to place the elemental concentrations in
the range described in 1.1.
These test methods are under the jurisdiction of ASTM Committee D-2 on
Petroleum Products and Lubricants and are the direct responsibility of Subcommit-
3. Significance and Use
tee D02.03 on Elemental Analysis.
3.1 Some oils are formulated with organo-metallic additives
Current edition approved April 10, 1996. Published June 1996. Originally
published as D 4927 – 89. Last previous edition D 4927 – 93. which act as detergents, antioxidants, antiwear agents, and so
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 4927
forth. Some of these additives contain one or more of these specifications are available. Other grades may be used, pro-
elements: barium, calcium, phosphorus, sulfur, and zinc. These vided it is first ascertained that the reagent is of sufficiently
test methods provide a means of determining the concentration high purity to permit its use without lessening the accuracy of
of these elements which in turn provides an indication of the the determination.
additive content of these oils.
TEST METHOD A (INTERNAL STANDARD
PROCEDURE)
4. Interferences
4.1 The additive elements found in lubricating oils will
7. Reagents and Materials
affect the measured intensities from the elements of interest to
7.1 Helium for optical path of spectrometer.
a varying degree. In general for lubricating oils, the X-radiation
7.2 P-10 Ionization Gas, 90 volume % argon and 10 volume
emitted by the element of interest is absorbed by the other
% methane for the flow proportional counter.
elements in the sample matrix. Also, the X-radiation emitted
7.3 Diluent Solvent, a suitable solvent free of metals, sulfur,
from one element can further excite another element. These
and phosphorus (for example, kerosine, white oil, or xylenes).
effects are significant at concentrations varying from 0.03 mass
7.4 Internal Standard Materials:
% due to the heavier elements to 1 mass % for the lighter
7.4.1 Nickel Octoate, preferably containing 5.0 6 0.1 mass
elements. The measured intensity for a given element can be
% nickel. If the nickel concentration is higher or lower
mathematically corrected for the absorption of the emitted
(minimum concentration that can be used is 2.5 6 0.1 mass %
radiation by the other elements present in the sample specimen.
nickel), the laboratory needs to adjust the amount of sample
Suitable internal standards can also compensate for X-ray
taken in 8.1.1 to yield an equivalent nickel concentration level
inter-element effects. If an element is present at significant
in the internal standard. Other nickel-containing organic ma-
concentrations and an interelement correction for that element
trices (free of other metals, sulfur, and phosphorus) may be
is not employed, the results can be low due to absorption or
substituted provided the nickel is stable in solution, the
high due to enhancement.
concentration is known ($2.56 0.1 mass % nickel), and the
laboratory can adjust the amount of sample taken in 8.1.1 to
5. Apparatus
yield an equivalent nickel concentration level in the internal
5.1 X-Ray Spectrometer equipped for soft X-ray detection standard if the nickel concentration does not initially contain
˚
5.0 6 0.1 mass % nickel.
of radiation in the range from 1 to 10 A. For optimum
sensitivity, the spectrometer is equipped with the following:
NOTE 2—Many X-ray tubes emit copper X rays which increase in
5.1.1 X-Ray Generating Tube with chromium, rhodium, or
intensity with age. This does not present a problem when using copper as
scandium target. Other targets can also be employed. an internal standard for zinc providing that frequent calibrations are
performed. No problem exists when using nickel as internal for zinc and
5.1.2 Helium, purgeable optical path.
nickel is the preferred internal standard material.
5.1.3 Interchangeable Crystals, germanium, lithium fluo-
7.4.2 Titanium 2-Ethylhexoide or Tin Octoate, preferably
ride (LIF ), graphite, or polyethylene terephthalate (PET), or
containing 8.0 6 0.1 mass % titanium or tin. If the titanium or
a combination thereof. Other crystals can also be used.
tin concentration is higher or lower (minimum concentration
5.1.4 Pulse-Height Analyzer or other means of energy dis-
that can be used is 4.0 6 0.1 mass % titanium or tin), the
crimination.
laboratory needs to adjust the amount of sample taken in 8.1.1
5.1.5 Detector, flow proportional, or scintillation, or flow
to yield an equivalent titanium or tin concentration level in the
proportional and scintillation counter.
internal standard. Other titanium or tin containing organic
5.2 Shaker, Mechanical Stirrer, or Ultrasonic Bath, capable
matrices (free of other metals, sulfur, and phosphorus) may be
of handling from 30-mL to 1-L bottles.
substituted, provided the titanium or tin is stable in solution,
5.3 X-Ray Disposable Plastic Cells, with suitable film
the concentration is known ($4.06 0.1 mass % titanium or
window. Suitable films include Mylar , polypropylene, or
tin), and the laboratory can adjust the amount of sample taken
polyimid with film thicknesses between 0.25 to 0.35 mil (6.3 to
in 8.1.1 to yield an equivalent titanium or tin concentration
8.8 μm).
level in the internal standard if the titanium or tin concentration
does not initially contain 8.0 6 0.1 mass % titanium or tin.
NOTE 1—Some films contain contamination of the elements of interest
7.4.3 Zirconium Octoate, preferably containing 12.0 6 0.1
(Mylar in particular). The magnitude of the contamination is assessed and
the same film batch used throughout the entire analysis.
mass % zirconium. If the laboratory uses zirconium octoate
with a lower mass % zirconium concentration level, the
6. Purity of Reagents
laboratory needs to evaporate away the petroleum solvent to
yield a solution that contains 12.0 6 0.1 mass % zirconium.
6.1 Reagent grade chemicals shall be used in all tests.
Unless otherwise indicated, it is intended that all reagents shall
conform to the specifications of the Committee on Analytical
Reagent Chemicals, American Chemical Society Specifications, American
Reagents of the American Chemical Society, where such
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
A registered trademark of E. I. du Pont de Nemours and Co. MD.
D 4927
C 5 720 2 A 1 B (3)
Other zirconium containing organic matrices (free of other @ #
metals, sulfur, and phosphorus) may be substituted, provided
where:
the zirconium is stable in solution and the concentration is
A = nickel containing material in blend, g,
known and does not exceed 12.0 6 0.1 mass % zirconium. If
B = titanium or tin containing material in blend, g,
the zirconium concentration is <12.0 6 0.1 mass %, the
C = diluent to add to blend, g,
laboratory needs to evaporate away the petroleum solvent to
x = nickel in material chosen as an internal standard,
yield a solution that contains 12.0 6 0.1 mass % zirconium.
mass %, and
7.4.4 Lead Naphthenate, containing 24.0 6 0.1 mass %
y = titanium or tin in material chosen as an internal
lead.
standard, mass %.
7.5 Calibration Standard Materials:
8.2 Sulfur:
NOTE 3—In addition to calibration standards identified in 7.5.1-7.5.5, 8.2.1 Lead Naphthenate (Warning—see Note 4), 24 mass
single-element or multielement calibration standards may also be prepared
% lead, serves as a suitable internal standard. No further
from materials similar to the samples being analyzed, provided the
treatment of this compound is necessary.
calibration standards to be used have previously been characterized by
independent primary (for example, gravimetric or volumetric) analytical NOTE 4—Warning: Hazardous. Lead naphthenate is toxic and precau-
techniques to establish the elemental concentration mass % levels. tions should be taken to avoid inhalation of vapors, ingestion, or skin
contact.
7.5.1 Barium 2-Ethylhexoide or Sulfonate, with concentra-
tions $4 mass % barium and certified to better than 60.1%
9. Preparation of Calibration Standards
relative, so that calibration standards can be prepared as stated
9.1 Barium, Calcium, Phosphorus, and Zinc:
in 9.1.1 and 9.1.2.
9.1.1 For concentrations less than 0.1 mass %, prepare
7.5.2 Calcium Octoate or Sulfonate, with concentrations $
standards containing 0.00, 0.01, 0.025, 0.050, 0.075, and 0.10
4 mass % calcium and certified to better than 60.1 % relative,
mass % of each respective element in the diluent solvent.
so that calibration standards can be prepared as stated in 9.1.1
and 9.1.2. 9.1.2 For concentrations greater than 0.1 mass %, prepare
7.5.3 Bis(2-Ethylhexyl)Hydrogen Phosphate, 97 % purity standards containing 0.00, 0.10, 0.25, 0.50, 0.75, and 1.00 mass
(9.62 mass % phosphorus). Other phosphorus containing % of each respective element in the diluent solvent.
organic matrices (free of other metals) may be substituted 9.1.3 Dispense 1.000 6 0.001 g of the zirconium internal
provided the phosphorus is stable in solution and the concen-
standard solution described in 7.4.3 into a 30-mL bottle.
tration is $4 mass % phosphorus and certified to better than Prepare an individual bottle for each of the calibration stan-
60.1 % relative, so that calibration standards can be prepared
dards.
as stated in 9.1.1 and 9.1.2.
9.1.4 Dispense 1.000 6 0.001 g of the internal standard
7.5.4 Zinc Sulfonate or Octoate, with concentration $4
solution described in 8.1.1 into a 30-mL bottle. Repeat for all
mass % zinc and certified to better than 60.1 % relative, so
of the calibration-standard bottles.
that calibration standards can be prepared as stated in 9.1.1 and
9.1.5 Add 8.00 6 0.001 g of each standard to a respective
9.1.2.
bottle containing the internal standards and shake or stir well
7.5.5 Di-n-Butyl Sulfide, 97 % purity, (21.9 mass % su
...
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