ASTM D7040-04(2015)
(Test Method)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
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
SIGNIFICANCE AND USE
4.1 This test method usually requires several minutes per sample. Other test methods which can be used for the determination of phosphorus in lubricating oils include WDXRF Test Method D4927 and ICPAES Test Methods D4951 and D5185. However, this test method provides more precise results than Test Methods D4951 or D5185.
4.2 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 unused lubricating oils meet specifications with respect to elemental composition.
4.3 It is expected that GF 4 grade engine oils marketed in the years 2004 to 2005 will have a maximum phosphorus concentration level of 500 mg/kg to 800 mg/kg. These limits are required to minimize poisoning of automotive emission control catalysts by volatile phosphorus species. It is anticipated that the later grades of oils may have even lower phosphorus levels.
SCOPE
1.1 This test method covers the quantitative determination of phosphorus in unused lubricating oils, such as International Lubricant Standardization and Approval Committee (ILSAC) GF 4 and similar grade engine oils, by inductively coupled plasma atomic emission spectrometry.
1.2 The precision statements are valid for dilutions in which the mass % sample in solvent is held constant in the range of 1mass % to 5 mass % oil.
1.3 The precision tables define the concentration ranges covered in the interlaboratory study (500 mg/kg to 800 mg/kg). 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 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D7040 − 04 (Reapproved 2015)
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.
1. Scope D4307Practice for Preparation of Liquid Blends for Use as
Analytical Standards
1.1 This test method covers the quantitative determination
D4927Test Methods for Elemental Analysis of Lubricant
of phosphorus in unused lubricating oils, such as International
and Additive Components—Barium, Calcium,
Lubricant Standardization and Approval Committee (ILSAC)
Phosphorus, Sulfur, and Zinc by Wavelength-Dispersive
GF 4 and similar grade engine oils, by inductively coupled
X-Ray Fluorescence Spectroscopy
plasma atomic emission spectrometry.
D4951TestMethodforDeterminationofAdditiveElements
1.2 Theprecisionstatementsarevalidfordilutionsinwhich
in Lubricating Oils by Inductively Coupled Plasma
the mass% sample in solvent is held constant in the range of
Atomic Emission Spectrometry
1mass% to 5 mass% oil.
D5185Test Method for Multielement Determination of
1.3 The precision tables define the concentration ranges Used and Unused Lubricating Oils and Base Oils by
Inductively Coupled Plasma Atomic Emission Spectrom-
covered in the interlaboratory study (500 mg⁄kg to
800mg⁄kg). However, both lower and higher concentrations etry (ICP-AES)
D6299Practice for Applying Statistical Quality Assurance
can be determined by this test method. The low concentration
limits are dependent on the sensitivity of the ICP instrument and Control Charting Techniques to Evaluate Analytical
Measurement System Performance
and the dilution factor. The high concentration limits are
determined by the product of the maximum concentration D6792Practice for Quality System in Petroleum Products
and Lubricants Testing Laboratories
defined by the linear calibration curve and the sample dilution
factor.
3. Summary of Test Method
1.4 The values stated in SI units are to be regarded as the
3.1 A sample portion is weighed and diluted by mass with
standard. The values given in parentheses are for information
mixed xylenes or other solvent.An internal standard, which is
only.
required,iseitherweighedseparatelyintothetestsolutionoris
1.5 This standard does not purport to address all of the
previously combined with the dilution solvent. Calibration
safety concerns, if any, associated with its use. It is the
standards are prepared similarly. The solutions are introduced
responsibility of the user of this standard to establish appro-
to the ICP instrument by a peristaltic pump (required). By
priate safety and health practices and determine the applica-
comparing emission intensity of phosphorus in the test speci-
bility of regulatory limitations prior to use.
men with emission intensities measured with the calibration
standardsandbyapplyingtheappropriateinternalstandardand
2. Referenced Documents
2 background corrections, the concentrations of phosphorus in
2.1 ASTM Standards:
the sample is calculated.
D4057Practice for Manual Sampling of Petroleum and
Petroleum Products
4. Significance and Use
4.1 This test method usually requires several minutes per
This test method is under the jurisdiction of ASTM Committee D02 on
sample. Other test methods which can be used for the deter-
Petroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility of
Subcommittee D02.03 on Elemental Analysis.
mination of phosphorus in lubricating oils include WDXRF
Current edition approved April 1, 2015. Published June 2015. Originally
Test Method D4927 and ICPAES Test Methods D4951 and
approved in 2004. Last previous edition approved in 2010 as D7040–04 (2010).
D5185. However, this test method provides more precise
DOI: 10.1520/D7040-04R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or results than Test Methods D4951 or D5185.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
4.2 Lubricating oils are typically blends of additive
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. packages, and their specifications are also determined, in part,
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7040 − 04 (2015)
by elemental composition. This test method can be used to 6.7 Ultrasonic Homogenizer (Optional)—A bath-type or
determine if unused lubricating oils meet specifications with probe-type ultrasonic homogenizer can be used to homogenize
respect to elemental composition. the test specimen.
4.3 It is expected that GF 4 grade engine oils marketed in
7. Reagents and Materials
the years 2004 to 2005 will have a maximum phosphorus
7.1 Purity of Reagents—Reagent grade chemicals shall be
concentration level of 500mg⁄kg to 800mg⁄kg. These limits
used in all tests. Unless otherwise indicated, it is intended that
are required to minimize poisoning of automotive emission
all reagents conform to the specifications of the Committee on
control catalysts by volatile phosphorus species. It is antici-
Analytical Reagents of theAmerican Chemical Society where
pated that the later grades of oils may have even lower
such specifications are available.
phosphorus levels.
7.2 Base Oil, U.S.P. white oil, or a lubricating base oil that
5. Interferences
is free of analytes, having a viscosity at room temperature as
close as possible to that of the samples to be analyzed.
5.1 Spectral—There are no known spectral interferences
between phosphorus and other elements covered by this test
7.3 Internal Standard (Required)—An oil-soluble internal
method when using the spectral lines 177.51nm, 178.29nm,
standard element is required. The following internal standards
185.94nm, 213.62nm, 214.91nm, or 253.40nm for phospho-
were successfully used in the interlaboratory study on preci-
rus.Thesewavelengthsareonlysuggestedanddonotrepresent
sion:Co(mostcommon),Sc,andY.Otherappropriateinternal
all possible choices. Wavelengths below 190nm require a
standards may also be used.
vacuum or inert gas purged optical path be used. However, if
7.4 Organometallic Standards—Multi-element standards,
spectral interferences exist because of other interfering ele-
containing known concentrations (approximately 0.1 mass%)
ments or selection of other spectral lines, correct for the
of each element, can be prepared from the individual metal
interference using the technique described in Test Method
concentrates. Refer to Practice D4307 for a procedure for
D5185.
preparationofmulti-componentliquidblends.Whenpreparing
5.2 Viscosity Index Improver Effect—Viscosity index
multi-element standards, be certain that proper mixing is
improvers,whichcanbepresentinmulti-gradelubricatingoils,
achieved. Commercially available multi-element blends (with
can bias the measurements. However, the biases can be
known concentrations of each element at approximately 0.1
reducedtonegligibleproportionbyusingthespecifiedsolvent-
mass%) are also satisfactory.
to-sample dilution and an internal standard.
7.4.1 Itcanbeadvantageoustoselectconcentrationsthatare
typical of unused oils. However, it is imperative that concen-
6. Apparatus
trationsareselectedsuchthattheemissionintensitiesmeasured
6.1 Inductively-Coupled Plasma Atomic Emission with the working standards can be measured precisely (that is,
Spectrometer—Either a sequential or simultaneous spectrom- the emission intensities are significantly greater than back-
eter is suitable, if equipped with a quartz ICP torch and r-f ground) and that these standards represent the linear region of
generator to form and sustain the plasma. the calibration curve. Frequently, the instrument manufacturer
publishes guidelines for determining linear range.
6.2 Analytical Balance, capable of weighing to 0.001g or
7.4.2 Some commercially available organometallic stan-
0.0001g, capacity of 150g.
dards are prepared from metal sulfonates and, therefore,
6.3 Peristaltic Pump (Required)—A peristaltic pump is
contain sulfur.
required to provide a constant flow of solution. The pumping
7.4.3 Petroleum additives can also be used as organometal-
speed shall be in the range 0.5mL⁄min to 3mL⁄min. The
licstandardsiftheirusedoesnotadverselyaffectprecisionnor
pump tubing shall be able to withstand at least a 6h exposure
introduce significant bias.
to the dilution solvent. Fluoroelastomer copolymer tubing is
7.5 Dilution Solvent—Mixed xylenes, o-xylene, and kero-
recommended.
sine were successfully used in the interlaboratory study on
6.4 Solvent Dispenser (Optional)—Asolventdispensercali-
precision.
brated to deliver the required weight of diluent can be
advantageous. Ensure that solvent drip does not affect accu- 8. Internal Standardization (Required)
racy.
8.1 The internal standard procedure requires that every test
6.5 Specimen Solution Containers,ofappropriatesize,glass solution(sampleandstandard)havethesameconcentration(or
or polyolefin vials, or bottles with screw caps. a known concentration) of an internal standard element that is
not present in the original sample. The internal standard is
6.6 Vortexer (Optional)—Vortex the sample plus diluent
usually combined with the dilution solvent. Internal standard
mixture until the sample is completely dissolved.
Reagent Chemicals, American Chemical Society Specifications, American
Bansal, J. G., and McElroy, F. C., SAE Paper 932694, October 1993.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 (2015)
compensationistypicallyhandledinoneoftwodifferentways, 10.3.1 Generally, carbon buildup can be minimized by
summarized as follows: increasing the intermediate argon flow rate or lowering the
8.1.1 Calibrationcurvesarebasedonthemeasuredintensity torch, or both, relative to the load coil.
of each analyte divided (that is, scaled) by the measured
NOTE 3—Some manufacturers recommend even longer warm-up peri-
intensity of the internal standard per unit internal standard
ods to minimize changes in the slopes of the calibration curves.
element concentration. Concentrations for each analyte in the
10.4 Wavelength Profiling—Perform any wavelength profil-
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 10s.
internal standard concentration determined by analysis.
8.2 Dissolve the organometallic compound representing the
11. Preparation of Test Specimens
internalstandardindilutionsolventandtransfertoadispensing
11.1 Diluent—Diluent refers to the dilution solvent contain-
vessel. The stability of this solution shall be monitored and
ing the internal standard (refer to 8.2).
preparedfresh(typicallyweekly)whentheconcentrationofthe
11.2 Test specimen solutions are prepared in the same way
internal standard element changes significantly. The concen-
that calibration standards are prepared (refer to 12.2). The
tration of internal standard element shall be at least 100 times
mass% oil in diluent shall be the same for calibration
itsdetectionlimit.Aconcentrationintherangeof10mg⁄kgto
standards and test specimen solutions.
20mg⁄kg is typical.
11.2.1 Lubricating Oil Specimens—Weigh appropriate
NOTE 1—This test method specifies that the internal standard is
combinedwiththedilutionsolventbecausethistechniqueiscommonand
amount of the test specimen to the nearest 0.001g.The weight
efficient when preparing many samples. However, the internal standard
of the test specimen taken will vary depending upon the metal
can be added separately from the dilution solvent as long as the internal
concentrationofthespecimen.Dilutebymasswiththediluent.
standard concentration is constant or accurately known.
Mix well.
9. Sampling
11.3 Record all weights and calculate dilution factors by
dividingthesumoftheweightsofthediluent,sample,andbase
9.1 The objective of sampling is to obtain a test specimen
oil (if any) by the weight of the sample.
that is representative of the entire quantity. Thus, take labora-
tory samples in accordance with the instructions in Practice
11.4 The user of this test method has the option of selecting
D4057. The specific sampling technique can affect the accu-
the dilution factor, that is, the relative amounts of sample and
racy of this test method.
diluent.However,themass%sampleindiluent(forcalibration
standardsandtestspecimens)shallbeconstantthroughoutthis
10. Preparation of Apparatus
test method, and the mass% sample in diluent shall be in the
range of 1mass% to 5 mass%.
10.1 Instrument—Design differences between instruments,
11.4.1 All references to dilute and diluting in this test
ICP excitation sources, and different selected analytical wave-
method refer to the user-selected dilution.
lengths for individual spectrometers make it impractical to
detail the operating conditions. Consult the manufacturer’s
11.5 Blank—Prepare a blank by diluting the base oil or
instructionsforoperatingtheinstrumentwithorganicsolvents.
white oil with the diluent.
Set up the instrument for use with the particular dilution
11.6 Working S
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7040 − 04 (Reapproved 2010) D7040 − 04 (Reapproved 2015)
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. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the quantitative determination of phosphorus in unused lubricating oils, such as International
Lubricant Standardization and Approval Committee (ILSAC) GF 4 and similar grade engine oils, by inductively coupled plasma
atomic emission spectrometry.
1.2 The precision statements are valid for dilutions in which the mass % sample in solvent is held constant in the range of
11mass % to 5 mass % oil.
1.3 The precision tables define the concentration ranges covered in the interlaboratory study (500(500 mg ⁄kg to 800800 mg ⁄
mg/kg). kg). 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 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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.
2. Referenced Documents
2.1 ASTM Standards:
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards
D4927 Test Methods for Elemental Analysis of Lubricant and Additive Components—Barium, Calcium, Phosphorus, Sulfur,
and Zinc by Wavelength-Dispersive X-Ray Fluorescence Spectroscopy
D4951 Test Method for Determination of Additive Elements in Lubricating Oils by Inductively Coupled Plasma Atomic
Emission Spectrometry
D5185 Test Method for Multielement Determination of Used and Unused Lubricating Oils and Base Oils by Inductively
Coupled Plasma Atomic Emission Spectrometry (ICP-AES)
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
D6792 Practice for Quality System in Petroleum Products and Lubricants Testing Laboratories
3. Summary of Test Method
3.1 A sample portion is weighed and diluted by mass with mixed xylenes or other solvent. An internal standard, which is
required, is either weighed separately into the test solution or is previously combined with the dilution solvent. Calibration
standards are prepared similarly. The solutions are introduced to the ICP instrument by a peristaltic pump (required). By comparing
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products Products, Liquid Fuels, and Lubricantsand is the direct responsibility of
Subcommittee D02.03 on Elemental Analysis.
Current edition approved May 1, 2010April 1, 2015. Published May 2010June 2015. Originally approved in 2004. Last previous edition approved in 20042010 as
D7040–04.D7040 – 04 (2010). DOI: 10.1520/D7040-04R10.10.1520/D7040-04R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7040 − 04 (2015)
emission intensity of phosphorus in the test specimen with emission intensities measured with the calibration standards and by
applying the appropriate internal standard and background corrections, the concentrations of phosphorus in the sample is
calculated.
4. Significance and Use
4.1 This test method usually requires several minutes per sample. Other test methods which can be used for the determination
of phosphorus in lubricating oils include WDXRF Test Method D4927 and ICPAES Test Methods D4951 and D5185. However,
this test method provides more precise results than Test Methods D4951 or D5185.
4.2 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 unused lubricating oils meet specifications with respect to elemental
composition.
4.3 It is expected that GF 4 grade engine oils marketed in the years 2004-2005 2004 to 2005 will have a maximum phosphorus
concentration level of 500500 mg ⁄kg to 800800 mg ⁄ mg/kg. kg. These limits are required to minimize poisoning of automotive
emission control catalysts by volatile phosphorus species. It is anticipated that the later grades of oils may have even lower
phosphorus levels.
5. Interferences
5.1 Spectral—There are no known spectral interferences between phosphorus and other elements covered by this test method
when using the spectral lines 177.51, 178.29, 185.94, 213.62, 214.91, or 253.40 nm 177.51 nm, 178.29 nm, 185.94 nm, 213.62 nm,
214.91 nm, or 253.40 nm for phosphorus. These wavelengths are only suggested and do not represent all possible choices.
Wavelengths below 190 nm 190 nm require a vacuum or inert gas purged optical path be used. However, if spectral interferences
exist because of other interfering elements or selection of other spectral lines, correct for the interference using the technique
described in Test Method D5185.
5.2 Viscosity Index Improver Effect—Viscosity index improvers, which can be present in multi-grade lubricating oils, can bias
the measurements. However, the biases can be reduced to negligible proportion by using the specified solvent-to-sample dilution
and an internal standard.
6. Apparatus
6.1 Inductively-Coupled Plasma Atomic Emission Spectrometer—Either a sequential or simultaneous spectrometer is suitable,
if equipped with a quartz ICP torch and r-f generator to form and sustain the plasma.
6.2 Analytical Balance, capable of weighing to 0.001 g or 0.0001 g, 0.001 g or 0.0001 g, capacity of 150 g.150 g.
6.3 Peristaltic Pump (Required)—A peristaltic pump is required to provide a constant flow of solution. The pumping speed shall
be in the range 0.50.5 mL ⁄min to 33 mL ⁄ mL/min. min. The pump tubing shall be able to withstand at least a 6-h6 h exposure
to the dilution solvent. Fluoroelastomer copolymer tubing is recommended.
6.4 Solvent Dispenser (Optional)—A solvent dispenser calibrated to deliver the required weight of diluent can be advantageous.
Ensure that solvent drip does not affect accuracy.
6.5 Specimen Solution Containers, of appropriate size, glass or polyolefin vials, or bottles with screw caps.
6.6 Vortexer (Optional)—Vortex the sample plus diluent mixture until the sample is completely dissolved.
6.7 Ultrasonic Homogenizer (Optional)—A bath-type or probe-type ultrasonic homogenizer can be used to homogenize the test
specimen.
7. Reagents and Materials
7.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such
specifications are available.
7.2 Base Oil, U.S.P. white oil, or a lubricating base oil that is free of analytes, having a viscosity at room temperature as close
as possible to that of the samples to be analyzed.
Bansal, J. G., and McElroy, F. C., SAE Paper 932694, October 1993. Available from Society of Automotive Engineers (SAE), 400 Commonwealth Dr., Warrendale, PA
15096-0001.
Fluoroelastomer copolymer is manufactured as Viton, a trademark owned by E. I. duPont de Nemours.
Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Suggestions on the testing of reagents not listed by
the American Chemical Society, see Annual Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National
Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
D7040 − 04 (2015)
7.3 Internal Standard (Required)—An oil-soluble internal standard element is required. The following internal standards were
successfully used in the interlaboratory study on precision: Co (most common), Sc, and Y. Other appropriate internal standards may
also be used.
7.4 Organometallic Standards—Multi-element standards, containing known concentrations (approximately 0.1 mass %) of each
element, can be prepared from the individual metal concentrates. Refer to Practice D4307 for a procedure for preparation of
multi-component liquid blends. When preparing multi-element standards, be certain that proper mixing is achieved. Commercially
available multi-element blends (with known concentrations of each element at approximately 0.1 mass %) are also satisfactory.
7.4.1 It can be advantageous to select concentrations that are typical of unused oils. However, it is imperative that concentrations
are selected such that the emission intensities measured with the working standards can be measured precisely (that is, the emission
intensities are significantly greater than background) and that these standards represent the linear region of the calibration curve.
Frequently, the instrument manufacturer publishes guidelines for determining linear range.
7.4.2 Some commercially available organometallic standards are prepared from metal sulfonates and, therefore, contain sulfur.
7.4.3 Petroleum additives can also be used as organometallic standards if their use does not adversely affect precision nor
introduce significant bias.
7.5 Dilution Solvent—Mixed xylenes, o-xylene, and kerosine were successfully used in the interlaboratory study on precision.
8. Internal Standardization (Required)
8.1 The internal standard procedure requires that every test solution (sample and standard) have the same concentration (or a
known concentration) of an internal standard element that is not present in the original sample. The internal standard is usually
combined with the dilution solvent. Internal standard compensation is typically handled in one of two different ways, summarized
as follows:
8.1.1 Calibration curves are based on the measured intensity of each analyte divided (that is, scaled) by the measured intensity
of the internal standard per unit internal standard element concentration. Concentrations for each analyte in the test specimen
solution are read directly from these calibration curves.
8.1.2 For each analyte and the internal standard element, calibration curves are based on measured (unscaled) intensities.
Uncorrected concentrations for each analyte in the test specimen solution are read from these calibration curves. Corrected analyte
concentrations are calculated by multiplying the uncorrected concentrations by a factor equal to the actual internal standard
concentration divided by the uncorrected internal standard concentration determined by analysis.
8.2 Dissolve the organometallic compound representing the internal standard in dilution solvent and transfer to a dispensing
vessel. The stability of this solution shall be monitored and prepared fresh (typically weekly) when the concentration of the internal
standard element changes significantly. The concentration of internal standard element shall be at least 100 times its detection limit.
A concentration in the range of 1010 mg ⁄kg to 2020 mg ⁄ mg/kg kg is typical.
NOTE 1—This test method specifies that the internal standard is combined with the dilution solvent because this technique is common and efficient when
preparing many samples. However, the internal standard can be added separately from the dilution solvent as long as the internal standard concentration
is constant or accurately known.
9. Sampling
9.1 The objective of sampling is to obtain a test specimen that is representative of the entire quantity. Thus, take laboratory
samples in accordance with the instructions in Practice D4057. The specific sampling technique can affect the accuracy of this test
method.
10. Preparation of Apparatus
10.1 Instrument—Design differences between instruments, ICP excitation sources, and different selected analytical wavelengths
for individual spectrometers make it impractical to detail the operating conditions. Consult the manufacturer’s instructions for
operating the instrument with organic solvents. Set up the instrument for use with the particular dilution solvent chosen.
10.2 Peristaltic Pump—Inspect the pump tubing and replace it, if necessary, before starting each day. Verify the solution uptake
rate and adjust it to the desired rate.
10.3 ICP Excitation Source—Initiate the plasma source at least 30 min before performing an analysis. During this warm-up
period, nebulize the dilution solvent. Inspect the torch for carbon buildup during the warm-up period. If carbon buildup occurs,
replace the torch immediately and consult the manufacturer’s operating guide to take proper steps to remedy the situation.
NOTE 2—Carbon that accumulates on the tip of the torch injector tube can be removed by using nebulizer gas that consists of approximately 1 % oxygen
in argon.
10.3.1 Generally, carbon buildup can be minimized by increasing the intermediate argon flow rate or lowering the torch, or both,
relative to the load coil.
NOTE 3—Some manufacturers recommend even longer warm-up periods to minimize changes in the slopes of the calibration curves.
10.4 Wavelength Profiling—Perform any wavelength profiling that is specified in the normal operation of the instrument.
D7040 − 04 (2015)
10.5 Operating Parameters—Assign the appropriate operating parameters to the instrument task file so that the desired elements
can be determined. Parameters to be included are element, wavelength, background correcti
...
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