ASTM D7040-04

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation:D7040–04
Standard Test Method for
Determination of Low Levels of Phosphorus in ILSAC GF 4
and Similar Grade Engine Oils by Inductively Coupled
Plasma Atomic Emission Spectrometry
This standard is issued under the fixed designation D7040; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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 D4307 Practice for Preparation of Liquid Blends for Use as
Analytical Standards
1.1 This test method covers the quantitative determination
D4927 Test Methods for Elemental Analysis of Lubricant
of phosphorus in unused lubricating oils, such as International
and Additive Components—Barium, Calcium, Phospho-
Lubricant Standardization and Approval Committee (ILSAC)
rus, Sulfur, and Zinc by Wavelength-Dispersive X-Ray
GF 4 and similar grade engine oils, by inductively coupled
Fluorescence Spectroscopy
plasma atomic emission spectrometry.
D4951 Test Method for Determination of Additive Ele-
1.2 Theprecisionstatementsarevalidfordilutionsinwhich
ments in Lubricating Oils by Inductively Coupled Plasma
the mass% sample in solvent is held constant in the range of
Atomic Emission Spectrometry
1 to 5 mass% oil.
D5185 Test Method for Determination of Additive Ele-
1.3 The precision tables define the concentration ranges
ments, Wear Metals, and Contaminants in Used Lubricat-
covered in the interlaboratory study (500 to 800 mg/kg).
ing Oils and Determination of Selected Elements in Base
However, both lower and higher concentrations can be deter-
Oils by Inductively Coupled Plasma Atomic Emission
mined by this test method. The low concentration limits are
Spectrometry (ICP-AES)
dependent on the sensitivity of the ICP instrument and the
D6299 Practice for Applying Statistical Quality Assurance
dilutionfactor.Thehighconcentrationlimitsaredeterminedby
and Control Charting Techniques to Evaluate Analytical
the product of the maximum concentration defined by the
Measurement System Performance
linear calibration curve and the sample dilution factor.
D6792 Practice for Quality System in Petroleum Products
1.4 The values stated in SI units are to be regarded as the
and Lubricants Testing Laboratories
standard. The values given in parentheses are for information
only.
3. Summary of Test Method
1.5 This standard does not purport to address all of the
3.1 A sample portion is weighed and diluted by mass with
safety concerns, if any, associated with its use. It is the
mixed xylenes or other solvent.An internal standard, which is
responsibility of the user of this standard to establish appro-
required,iseitherweighedseparatelyintothetestsolutionoris
priate safety and health practices and determine the applica-
previously combined with the dilution solvent. Calibration
bility of regulatory limitations prior to use.
standards are prepared similarly. The solutions are introduced
2. Referenced Documents to the ICP instrument by a peristaltic pump (required). By
2 comparing emission intensity of phosphorus in the test speci-
2.1 ASTM Standards:
men with emission intensities measured with the calibration
D4057 Practice for Manual Sampling of Petroleum and
standardsandbyapplyingtheappropriateinternalstandardand
Petroleum Products
background corrections, the concentrations of phosphorus in
the sample is calculated.
This test method is under the jurisdiction of ASTM Committee D02 on 4. Significance and Use
PetroleumProductsandLubricantsandisthedirectresponsibilityofSubcommittee
4.1 This test method usually requires several minutes per
D02.03 on Elemental Analysis.
sample. Other test methods which can be used for the deter-
Current edition approved Aug. 1, 2004. Published August 2004. DOI: 10.1520/
D7040-04.
mination of phosphorus in lubricating oils include WDXRF
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Test Method D4927 and ICPAES Test Methods D4951 and
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
D5185. However, this test method provides more precise
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. results than Test Methods D4951 or D5185.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D7040–04
4.2 Lubricating oils are typically blends of additive pack- 7. Reagents and Materials
ages, and their specifications are also determined, in part, by
7.1 Purity of Reagents—Reagent grade chemicals shall be
elemental composition. This test method can be used to
used in all tests. Unless otherwise indicated, it is intended that
determine if unused lubricating oils meet specifications with
all reagents conform to the specifications of the Committee on
respect to elemental composition.
Analytical Reagents of theAmerican Chemical Society where
4.3 It is expected that GF 4 grade engine oils marketed in
such specifications are available.
the years 2004-2005 will have a maximum phosphorus con-
7.2 Base Oil, U.S.P. white oil, or a lubricating base oil that
centrationlevelof500to800mg/kg.Theselimitsarerequired
is free of analytes, having a viscosity at room temperature as
tominimizepoisoningofautomotiveemissioncontrolcatalysts
close as possible to that of the samples to be analyzed.
by volatile phosphorus species. It is anticipated that the later
7.3 Internal Standard (Required)—An oil-soluble internal
grades of oils may have even lower phosphorus levels.
standard element is required. The following internal standards
were successfully used in the interlaboratory study on preci-
5. Interferences
sion:Co(mostcommon),Sc,andY.Otherappropriateinternal
5.1 Spectral—There are no known spectral interferences
standards may also be used.
between phosphorus and other elements covered by this test
7.4 Organometallic Standards—Multi-element standards,
method when using the spectral lines 177.51, 178.29, 185.94, containing known concentrations (approximately 0.1 mass%)
213.62, 214.91, or 253.40 nm for phosphorus. These wave-
of each element, can be prepared from the individual metal
lengths are only suggested and do not represent all possible concentrates. Refer to Practice D4307 for a procedure for
choices.Wavelengths below 190 nm require a vacuum or inert
preparationofmulti-componentliquidblends.Whenpreparing
gas purged optical path be used. However, if spectral interfer- multi-element standards, be certain that proper mixing is
encesexistbecauseofotherinterferingelementsorselectionof
achieved. Commercially available multi-element blends (with
other spectral lines, correct for the interference using the known concentrations of each element at approximately 0.1
technique described in Test Method D5185.
mass%) are also satisfactory.
5.2 Viscosity Index Improver Effect—Viscosity index im- 7.4.1 Itcanbeadvantageoustoselectconcentrationsthatare
provers, which can be present in multi-grade lubricating oils,
typical of unused oils. However, it is imperative that concen-
can bias the measurements. However, the biases can be trationsareselectedsuchthattheemissionintensitiesmeasured
reducedtonegligibleproportionbyusingthespecifiedsolvent-
with the working standards can be measured precisely (that is,
to-sample dilution and an internal standard. the emission intensities are significantly greater than back-
ground) and that these standards represent the linear region of
6. Apparatus
the calibration curve. Frequently, the instrument manufacturer
publishes guidelines for determining linear range.
6.1 Inductively-Coupled Plasma Atomic Emission
7.4.2 Some commercially available organometallic stan-
Spectrometer—Either a sequential or simultaneous spectrom-
dards are prepared from metal sulfonates and, therefore,
eter is suitable, if equipped with a quartz ICP torch and r-f
contain sulfur.
generator to form and sustain the plasma.
7.4.3 Petroleum additives can also be used as organometal-
6.2 Analytical Balance, capable of weighing to 0.001 g or
licstandardsiftheirusedoesnotadverselyaffectprecisionnor
0.0001 g, capacity of 150 g.
introduce significant bias.
6.3 Peristaltic Pump (Required)—A peristaltic pump is
7.5 Dilution Solvent—Mixed xylenes, o-xylene, and kero-
required to provide a constant flow of solution. The pumping
sine were successfully used in the interlaboratory study on
speed shall be in the range 0.5 to 3 mL/min. The pump tubing
precision.
shallbeabletowithstandatleasta6-hexposuretothedilution
solvent. Fluoroelastomer copolymer tubing is recommended.
8. Internal Standardization (Required)
6.4 Solvent Dispenser (Optional)—Asolventdispensercali-
8.1 The internal standard procedure requires that every test
brated to deliver the required weight of diluent can be
solution(sampleandstandard)havethesameconcentration(or
advantageous. Ensure that solvent drip does not affect accu-
a known concentration) of an internal standard element that is
racy.
not present in the original sample. The internal standard is
6.5 Specimen Solution Containers,ofappropriatesize,glass
usually combined with the dilution solvent. Internal standard
or polyolefin vials, or bottles with screw caps.
compensationistypicallyhandledinoneoftwodifferentways,
6.6 Vortexer (Optional)—Vortex the sample plus diluent
summarized as follows:
mixture until the sample is completely dissolved.
8.1.1 Calibrationcurvesarebasedonthemeasuredintensity
6.7 Ultrasonic Homogenizer (Optional)—A bath-type or
of each analyte divided (that is, scaled) by the measured
probe-type ultrasonic homogenizer can be used to homogenize
intensity of the internal standard per unit internal standard
the test specimen.
Reagent Chemicals, American Chemical Society Specifications, American
Bansal,J.G.,andMcElroy,F.C., SAE Paper 932694,October1993.Available Chemical Society, Washington, DC. For Suggestions on the testing of reagents not
fromSocietyofAutomotiveEngineers(SAE),400CommonwealthDr.,Warrendale, listed by the American Chemical Society, see Annual Standards for Laboratory
PA 15096-0001. Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
FluoroelastomercopolymerismanufacturedasViton,atrademarkownedbyE. and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
I. duPont de Nemours. MD.
D7040–04
element concentration. Concentrations for each analyte in the 10.4 Wavelength Profiling—Performanywavelengthprofil-
test specimen solution are read directly from these calibration ing that is specified in the normal operation of the instrument.
curves. 10.5 Operating Parameters—Assign the appropriate oper-
8.1.2 For each analyte and the internal standard element, ating parameters to the instrument task file so that the desired
calibration curves are based on measured (unscaled) intensi- elements can be determined. Parameters to be included are
ties. Uncorrected concentrations for each analyte in the test element, wavelength, background correction points (required),
specimen solution are read from these calibration curves. interelement correction factors (refer to 5.1), integration time,
Corrected analyte concentrations are calculated by multiplying and internal standard compensation (required). Multiple inte-
the uncorrected concentrations by a factor equal to the actual grations(typicallythree)arerequiredforeachmeasurement.A
internal standard concentration divided by the uncorrected typical integration time is 10 s.
internal standard concentration determined by analysis.
11. Preparation of Test Specimens
8.2 Dissolve the organometallic compound representing the
11.1 Diluent—Diluentreferstothedilutionsolventcontain-
internalstandardindilutionsolventandtransfertoadispensing
ing the internal standard (refer to 8.2).
vessel. The stability of this solution shall be monitored and
11.2 Test specimen solutions are prepared in the same way
preparedfresh(typicallyweekly)whentheconcentrationofthe
internal standard element changes significantly. The concen- that calibration standards are prepared (refer to 12.2). The
mass% oil in diluent shall be the same for calibration
tration of internal standard element shall be at least 100 times
its detection limit. A concentration in the range of 10 to 20 standards and test specimen solutions.
11.2.1 Lubricating Oil Specimens—Weigh appropriate
mg/kg is typical.
amountofthetestspecimentothenearest0.001g.Theweight
NOTE 1—This test method specifies that the internal standard is
of the test specimen taken will vary depending upon the metal
combinedwiththedilutionsolventbecausethistechniqueiscommonand
concentrationofthespecimen.Dilutebymasswiththediluent.
efficient when preparing many samples. However, the internal standard
Mix well.
can be added separately from the dilution solvent as long as the internal
standard concentration is constant or accurately known. 11.3 Record all weights and calculate dilution factors by
dividingthesumoftheweightsofthediluent,sample,andbase
9. Sampling
oil (if any) by the weight of the sample.
9.1 The objective of sampling is to obtain a test specimen
11.4 Theuserofthistestmethodhastheoptionofselecting
that is representative of the entire quantity. Thus, take labora-
the dilution factor, that is, the relative amounts of sample and
tory samples in accordance with the instructions in Practice
diluent.However,themass%sampleindiluent(forcalibration
D4057. The specific sampling technique can affect the accu-
standardsandtestspecimens)shallbeconstantthroughoutthis
racy of this test method.
test method, and the mass% sample in diluent shall be in the
range of 1 to 5 mass%.
10. Preparation of Apparatus
11.4.1 All references to dilute and diluting in this test
method refer to the user-selected dilution.
10.1 Instrument—Design differences between instruments,
11.5 Blank—Prepare a blank by diluting the base oil or
ICPexcitation sources, and different selected analytical wave-
white oil with the diluent.
lengths for individual spectrometers make it impractical to
11.6 Working Standards—Weigh to the nearest 0.001 g,
detail the operating conditions. Consult the manufacturer’s
approximately1to3gofeachmulti-elementstandard(referto
instructionsforoperatingtheinstrumentwithorganicsolvents.
7.4) into separate bottles. Dilute by mass with the diluent.
Set up the instrument for use with the particular dilution
11.7 Check Standard—Prepare instrument check standards
solvent chosen.
in the same manner as the working standards such that the
10.2 Peristaltic Pump—Inspect the pump tubing and re-
concentration
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