ASTM D4951-14(2019)
(Test Method)Standard Test Method for Determination of Additive Elements in Lubricating Oils by Inductively Coupled Plasma Atomic Emission Spectrometry
Standard Test Method for Determination of Additive Elements in Lubricating Oils by Inductively Coupled Plasma Atomic Emission Spectrometry
SIGNIFICANCE AND USE
4.1 This test method usually requires several minutes per sample. This test method covers eight elements and thus provides more elemental composition data than Test Method D4628 or Test Methods D4927. In addition, this test method provides more accurate results than Test Method D5185, which is intended for used lubricating oils and base oils.
4.2 Additive packages are blends of individual additives, which can act as detergents, antioxidants, antiwear agents, and so forth. Many additives contain one or more elements covered by this test method. Additive package specifications are based, in part, on elemental composition. Lubricating oils are typically blends of additive packages, and their specifications are also determined, in part, by elemental composition. This test method can be used to determine if additive packages and unused lubricating oils meet specifications with respect to elemental composition.
4.3 Several additive elements and their compounds are added to the lubricating oils to give beneficial performance (Table 1).
SCOPE
1.1 This test method covers the quantitative determination of barium, boron, calcium, copper, magnesium, molybdenum, phosphorus, sulfur, and zinc in unused lubricating oils and additive packages.
1.2 The precision statements are valid for dilutions in which the mass % sample in solvent is held constant in the range of 1 % to 5 % by mass of oil.
1.3 The precision tables define the concentration ranges covered in the interlaboratory study. However, both lower and higher concentrations can be determined by this test method. The low concentration limits are dependent on the sensitivity of the ICP instrument and the dilution factor. The high concentration limits are determined by the product of the maximum concentration defined by the linear calibration curve and the sample dilution factor.
1.4 Sulfur can be determined if the instrument can operate at a wavelength of 180 nm.
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D4951 − 14 (Reapproved 2019)
Standard Test Method for
Determination of Additive Elements in Lubricating Oils by
Inductively Coupled Plasma Atomic Emission Spectrometry
This standard is issued under the fixed designation D4951; 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 U.S. Department of Defense.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers the quantitative determination
of barium, boron, calcium, copper, magnesium, molybdenum, D1552 Test Method for Sulfur in Petroleum Products by
High Temperature Combustion and Infrared (IR) Detec-
phosphorus, sulfur, and zinc in unused lubricating oils and
additive packages. tion or Thermal Conductivity Detection (TCD)
D4057 Practice for Manual Sampling of Petroleum and
1.2 The precision statements are valid for dilutions in which
Petroleum Products
the mass % sample in solvent is held constant in the range of
D4307 Practice for Preparation of Liquid Blends for Use as
1 % to 5 % by mass of oil.
Analytical Standards
1.3 The precision tables define the concentration ranges
D4628 Test Method for Analysis of Barium, Calcium,
covered in the interlaboratory study. However, both lower and
Magnesium, and Zinc in Unused Lubricating Oils by
higher concentrations can be determined by this test method.
Atomic Absorption Spectrometry
The low concentration limits are dependent on the sensitivity
D4927 Test Methods for Elemental Analysis of Lubricant
of the ICP instrument and the dilution factor. The high
and Additive Components—Barium, Calcium,
concentration limits are determined by the product of the
Phosphorus, Sulfur, and Zinc by Wavelength-Dispersive
maximum concentration defined by the linear calibration curve
X-Ray Fluorescence Spectroscopy
and the sample dilution factor.
D5185 Test Method for Multielement Determination of
Used and Unused Lubricating Oils and Base Oils by
1.4 Sulfurcanbedeterminediftheinstrumentcanoperateat
Inductively Coupled Plasma Atomic Emission Spectrom-
a wavelength of 180 nm.
etry (ICP-AES)
1.5 The values stated in SI units are to be regarded as
D6299 Practice for Applying Statistical Quality Assurance
standard. No other units of measurement are included in this
and Control Charting Techniques to Evaluate Analytical
standard.
Measurement System Performance
1.6 This standard does not purport to address all of the
3. Summary of Test Method
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3.1 A sample portion is weighed and diluted by mass with
priate safety, health, and environmental practices and deter-
mixed xylenes or other solvent.An internal standard, which is
mine the applicability of regulatory limitations prior to use.
required,iseitherweighedseparatelyintothetestsolutionoris
1.7 This international standard was developed in accor-
previously combined with the dilution solvent. Calibration
dance with internationally recognized principles on standard-
standards are prepared similarly. The solutions are introduced
ization established in the Decision on Principles for the
to the ICP instrument by free aspiration or an optional
Development of International Standards, Guides and Recom-
peristaltic pump. By comparing emission intensities of ele-
mendations issued by the World Trade Organization Technical
ments in the test specimen with emission intensities measured
Barriers to Trade (TBT) Committee.
with the calibration standards and by applying the appropriate
internal standard correction, the concentrations of elements in
the sample are calculable.
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.03 on Elemental Analysis. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Dec. 1, 2019. Published December 2019. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1989. Last previous edition approved in 2014 as D4951 – 14. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D4951-14R19. 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
D4951 − 14 (2019)
TABLE 1 Lubricants and Additive Materials
Element Compound Performance
Barium Sulfonates, phenates Detergent inhibitors, corrosion inhibitors, detergents, rust inhibitors, and
ATF
Boron Inorganic borates and borate esters, borated Anti-wear agents, anti-oxidant, deodorant, cutting oils, and brake fluids
dispersants and detergents
Calcium Sulfonates, phenates Detergent inhibitors and dispersants
Copper Copper dithiophosphates Anti-wear agent and anti-oxidant
Magnesium Sulfonates, phenates Detergent inhibitors
Molybdenum Dialkylithiophosphate, dialkyldithiocarbamate, other Friction modifier additives
molybdenum complexes
Phosphorus Dithiophosphates, phosphates, and phosphites Anti-rusting agents, extreme pressure additives, and anti-wear
Sulfur Base oils, sulfonates, thiophosphates, polysulfides, Detergents, extreme pressure additives, and antiwear
and other sulfurized components
Zinc Dialkyldithiophosphates, dithiocarbamates, Anti-oxidant, corrosion inhibitors, anti-wear additives, detergents,
phenolates, carboxylates crankcase oils, hypoid gear lubricants, aircraft piston engine oils, turbine
oils, ATF, railroad diesel engine oils, and brake lubricants
4. Significance and Use eter is suitable, if equipped with a quartz ICP torch and RF
generator to form and sustain the plasma.
4.1 This test method usually requires several minutes per
sample. This test method covers eight elements and thus 6.2 Analytical Balance, capable of weighing to 0.001 g or
provides more elemental composition data than Test Method 0.0001 g, with sufficient capacity to weigh prepared solutions.
D4628 or Test Methods D4927. In addition, this test method
6.3 Peristaltic Pump, (Recommended)—A peristaltic pump
providesmoreaccurateresultsthanTestMethodD5185,which
is strongly recommended to provide a constant flow of solu-
is intended for used lubricating oils and base oils.
tion. The pumping speed must be in the range 0.5 mL⁄min to
4.2 Additive packages are blends of individual additives, 3 mL⁄min. The pump tubing must be able to withstand at least
which can act as detergents, antioxidants, antiwear agents, and 6 h exposure to the dilution solvent. Fluoroelastomer copoly-
soforth.Manyadditivescontainoneormoreelementscovered mer tubing is recommended.
by this test method.Additive package specifications are based,
6.4 Solvent Dispenser, (Optional)—Asolventdispensercali-
in part, on elemental composition. Lubricating oils are typi-
brated to deliver the required weight of diluent can be
cally blends of additive packages, and their specifications are
advantageous. Ensure that solvent drip does not affect accu-
also determined, in part, by elemental composition. This test
racy.
method can be used to determine if additive packages and
6.5 Specimen Solution Containers,ofappropriatesize,glass
unused lubricating oils meet specifications with respect to
or polyolefin vials or bottles, with screw caps.
elemental composition.
6.6 Vortexer, (Optional)—Vortex the sample plus diluent
4.3 Several additive elements and their compounds are
mixture until the sample is completely dissolved.
added to the lubricating oils to give beneficial performance
(Table 1). 6.7 Ultrasonic Homogenizer, Optional—A bath-type or
probe-typeultrasonichomogenizercanbeusedtohomogenizer
5. Interferences
the test specimen.
5.1 Spectral—There are no known spectral interferences
7. Reagents and Materials
between elements covered by this test method when using the
spectral lines listed in Table 2. However, if spectral interfer-
7.1 Purity of Reagents—Reagent grade chemicals shall be
encesexistbecauseofotherinterferingelementsorselectionof
used in all tests. Unless otherwise indicated, it is intended that
other spectral lines, correct for the interference using the
all reagents conform to the specifications of the Committee on
technique described in Test Method D5185.
Analytical Reagents of the American Chemical Society where
such specifications are available.
5.2 Viscosity Index Improver Effect—Viscosity index
improvers, which can be present in multigrade lubricating oils,
can bias measurements. However, the biases can be reduced to
Fluoroelastomer copolymer is manufactured asViton, a trademark owned by E.
negligible proportion by using the specified solvent-to-sample
I. duPont de Nemours.
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
dilution and an internal standard.
Standard-Grade Reference Materials, American Chemical Society, Washington,
6. Apparatus DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
6.1 Inductively-Coupled Plasma Atomic Emission
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
Spectrometer—Either a sequential or simultaneous spectrom- copeial Convention, Inc. (USPC), Rockville, MD.
D4951 − 14 (2019)
A
TABLE 2 Elements Determined and Suggested Wavelengths
Element Wavelength, nm
Barium 233.53, 455.40, 493.41
B
Boron 182.59, 249.68
Calcium 315.88, 317.93, 364.4, 422.67
Copper 324.75
Magnesium 279.08, 279.55, 285.21
Molybdenum 202.03, 281.62
B
Phosphorus 177.51, 178.29, 213.62, 214.91, 253.40
B
Sulfur 180.73, 182.04, 182.62
Zinc 202.55, 206.20, 213.86, 334.58, 481.05
A
These wavelengths are only suggested and do not represent all possible choices.
B
Wavelengths for boron, phosphorus, and sulfur below 190 nm require that a vacuum or inert gas purged optical path be used.
7.2 Base Oil, U.S.P. white oil, or a lubricating base oil that 7.5 Dilution Solvent—Mixed xylenes, o-xylene, and kero-
is free of analytes, having a viscosity at room temperature as sine were successfully used in the interlaboratory study on
close as possible to that of the samples to be analyzed. precision.
(Warning—Lubricating base oils can contain sulfur. For
8. Internal Standardization (Required)
preparation of sulfur standards and blending of additive
8.1 The internal standard procedure requires that every test
packages, white oil is recommended.)
solution(sampleandstandard)havethesameconcentration(or
7.3 Internal Standard, (Required)—An oil-soluble internal
a known concentration) of an internal standard element that is
standard element is required. The following internal standards
not present in the original sample. The internal standard is
were successfully used in the interlaboratory study on preci-
usually combined with the dilution solvent. Internal standard
sion: Ag, Be, Cd, Co (most common), La, Mn, Pb, Y.
compensationistypicallyhandledinoneoftwodifferentways,
7.4 Organometallic Standards—Multi-element standards,
which can be summarized as follows.
containing known concentrations (approximately 0.1 % by
8.1.1 Calibrationcurvesarebasedonthemeasuredintensity
mass) of each element, can be prepared from the individual
of each analyte divided (that is, scaled) by the measured
metalconcentrates.RefertoPracticeD4307foraprocedurefor
intensity of the internal standard per unit internal standard
preparation of multicomponent liquid blends. When preparing
element concentration. Concentrations for each analyte in the
multi-element standards, be certain that proper mixing is
test specimen solution are read directly from these calibration
achieved. Commercially available multi-element blends (with
curves.
known concentrations of each element at approximately 0.1 %
8.1.2 For each analyte and the internal standard element,
by mass) are also satisfactory.
calibration curves are based on measured (unscaled) intensi-
7.4.1 More than one multi-element standard can be neces-
ties. Uncorrected concentrations for each analyte in the test
sary to cover all elements, and the user of this test method can
specimen solution are read from these calibration curves.
select the combination of elements and their concentrations in
Corrected analyte concentrations are calculated by multiplying
the multi-element standards. It can be advantageous to select
the uncorrected concentrations by a factor equal to the actual
concentrations that are typical of unused oils. However, it is
internal standard concentration divided by the uncorrected
imperative that concentrations are selected such that the
internal standard concentration determined by analysis.
emission intensities measured with the working standards can
8.2 Dissolve the organometallic compound representing the
be measured precisely (that is, the emission intensities are
internalstandardindilutionsolventandtransfertoadispensing
significantly greater than background) and that these standards
vessel. The stability of this solution must be monitored and
represent the linear region of the calibration curve. Frequently,
preparedfresh(typicallyweekly)whentheconcentrationofthe
theinstrumentmanufacturerpublishesguidelinesfordetermin-
internal standard element changes significantly. The concen-
ing linear range.
tration of internal standard element shall be at least 100 times
7.4.2 Some commercially available organometallic stan-
its detection limit.Aconcentration in the range of 10 mg⁄kg to
dards are prepared from metal sulfonates and therefore contain
20 mg⁄kg is typical.
sulfur.Forsulfurdeterminations,aseparatesulfurstandardcan
NOTE 1—This test method specifies that the internal standard is
be required. A sulfur standard can be prepared by blending
combined with the dilution solvent because this technique is common and
NIST SRM 1622 with white oil.
efficient when preparing many samples. However, the internal standard
7.4.3 Metalsulfonatescanbeusedasasulfurstandardifthe
can be added separately from the dilution solvent as long as the internal
sulfur content is known or determined by an appropriate test
standard concentration is constant or accurately known.
method such as Test Method D1552.
9. Sampling
7.4.4 Petroleum additives can also be used as organometal-
lic s
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