1、Designation: D 7040 04An American National StandardStandard Test Method forDetermination of Low Levels of Phosphorus in ILSAC GF 4and Similar Grade Engine Oils by Inductively CoupledPlasma Atomic Emission Spectrometry1This standard is issued under the fixed designation D 7040; the number immediately
2、 following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been
3、 approved for use by agencies of the Department of Defense.1. Scope1.1 This test method covers the quantitative determinationof phosphorus in unused lubricating oils, such as InternationalLubricant Standardization and Approval Committee (ILSAC)GF 4 and similar grade engine oils, by inductively coupl
4、edplasma atomic emission spectrometry.1.2 The precision statements are valid for dilutions in whichthe mass % sample in solvent is held constant in the range of1 to 5 mass % oil.1.3 The precision tables define the concentration rangescovered in the interlaboratory study (500 to 800 mg/kg).However, b
5、oth lower and higher concentrations can be deter-mined by this test method. The low concentration limits aredependent on the sensitivity of the ICP instrument and thedilution factor. The high concentration limits are determined bythe product of the maximum concentration defined by thelinear calibrat
6、ion curve and the sample dilution factor.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of t
7、he user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4307 Practice for Preparation of L
8、iquid Blends for Use asAnalytical StandardsD 4927 Test Methods for Elemental Analysis of Lubricantand Additive ComponentsBarium, Calcium, Phospho-rus, Sulfur, and Zinc by Wavelength-Dispersive X-RayFluorescence SpectroscopyD 4951 Test Method for Determination of Additive Ele-ments in Lubricating Oil
9、s by Inductively Coupled PlasmaAtomic Emission SpectrometryD 5185 Test Method for Determination of Additive Ele-ments, Wear Metals, and Contaminants in Used Lubricat-ing Oils and Determination of Selected Elements in BaseOils by Inductively Coupled Plasma Atomic EmissionSpectrometry (ICP-AES)D 6299
10、Practice for Applying Statistical Quality AssuranceTechniques to Evaluate Analytical Measurement SystemPerformanceD 6792 Guide for a Quality System in Petroleum Productsand Lubricants Testing Laboratories3. Summary of Test Method3.1 A sample portion is weighed and diluted by mass withmixed xylenes o
11、r other solvent. An internal standard, which isrequired, is either weighed separately into the test solution or ispreviously combined with the dilution solvent. Calibrationstandards are prepared similarly. The solutions are introducedto the ICP instrument by a peristaltic pump (required). Bycomparin
12、g emission intensity of phosphorus in the test speci-men with emission intensities measured with the calibrationstandards and by applying the appropriate internal standard andbackground corrections, the concentrations of phosphorus inthe sample is calculated.4. Significance and Use4.1 This test meth
13、od usually requires several minutes persample. Other test methods which can be used for the deter-mination of phosphorus in lubricating oils include WDXRFTest Method D 4927 and ICPAES Test Methods D 4951 andD 5185. However, this test method provides more preciseresults than Test Methods D 4951 or D
14、5185.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved Aug. 1, 2004. Published August 2004.2For referenced ASTM standards, visit the ASTM website,
15、 www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4
16、.2 Lubricating oils are typically blends of additive pack-ages, and their specifications are also determined, in part, byelemental composition. This test method can be used todetermine if unused lubricating oils meet specifications withrespect to elemental composition.4.3 It is expected that GF 4 gr
17、ade engine oils marketed inthe years 2004-2005 will have a maximum phosphorus con-centration level of 500 to 800 mg/kg. These limits are requiredto minimize poisoning of automotive emission control catalystsby volatile phosphorus species. It is anticipated that the latergrades of oils may have even
18、lower phosphorus levels.5. Interferences5.1 SpectralThere are no known spectral interferencesbetween phosphorus and other elements covered by this testmethod when using the spectral lines 177.51, 178.29, 185.94,213.62, 214.91, or 253.40 nm for phosphorus. These wave-lengths are only suggested and do
19、 not represent all possiblechoices. Wavelengths below 190 nm require a vacuum or inertgas purged optical path be used. However, if spectral interfer-ences exist because of other interfering elements or selection ofother spectral lines, correct for the interference using thetechnique described in Tes
20、t Method D 5185.5.2 Viscosity Index Improver EffectViscosity index im-provers, which can be present in multi-grade lubricating oils,can bias the measurements.3However, the biases can bereduced to negligible proportion by using the specified solvent-to-sample dilution and an internal standard.6. Appa
21、ratus6.1 Inductively-Coupled Plasma Atomic EmissionSpectrometerEither a sequential or simultaneous spectrom-eter is suitable, if equipped with a quartz ICP torch and r-fgenerator to form and sustain the plasma.6.2 Analytical Balance, capable of weighing to 0.001 g or0.0001 g, capacity of 150 g.6.3 P
22、eristaltic Pump (Required)A peristaltic pump isrequired to provide a constant flow of solution. The pumpingspeed shall be in the range 0.5 to 3 mL/min. The pump tubingshall be able to withstand at least a 6-h exposure to the dilutionsolvent. Fluoroelastomer copolymer4tubing is recommended.6.4 Solven
23、t Dispenser (Optional)A solvent dispenser cali-brated to deliver the required weight of diluent can beadvantageous. Ensure that solvent drip does not affect accu-racy.6.5 Specimen Solution Containers, of appropriate size, glassor polyolefin vials, or bottles with screw caps.6.6 Vortexer (Optional)Vo
24、rtex the sample plus diluentmixture until the sample is completely dissolved.6.7 Ultrasonic Homogenizer (Optional)A bath-type orprobe-type ultrasonic homogenizer can be used to homogenizethe test specimen.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all test
25、s. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.57.2 Base Oil, U.S.P. white oil, or a lubricating base oil thatis free of analytes, having a vis
26、cosity at room temperature asclose as possible to that of the samples to be analyzed.7.3 Internal Standard (Required)An oil-soluble internalstandard element is required. The following internal standardswere successfully used in the interlaboratory study on preci-sion: Co (most common), Sc, and Y. Ot
27、her appropriate internalstandards may also be used.7.4 Organometallic StandardsMulti-element standards,containing known concentrations (approximately 0.1 mass %)of each element, can be prepared from the individual metalconcentrates. Refer to Practice D 4307 for a procedure forpreparation of multi-co
28、mponent liquid blends. When preparingmulti-element standards, be certain that proper mixing isachieved. Commercially available multi-element blends (withknown concentrations of each element at approximately 0.1mass %) are also satisfactory.7.4.1 It can be advantageous to select concentrations that a
29、retypical of unused oils. However, it is imperative that concen-trations are selected such that the emission intensities measuredwith the working standards can be measured precisely (that is,the emission intensities are significantly greater than back-ground) and that these standards represent the l
30、inear region ofthe calibration curve. Frequently, the instrument manufacturerpublishes guidelines for determining linear range.7.4.2 Some commercially available organometallic stan-dards are prepared from metal sulfonates and, therefore,contain sulfur.7.4.3 Petroleum additives can also be used as or
31、ganometal-lic standards if their use does not adversely affect precision norintroduce significant bias.7.5 Dilution SolventMixed xylenes, o-xylene, and kero-sine were successfully used in the interlaboratory study onprecision.8. Internal Standardization (Required)8.1 The internal standard procedure
32、requires that every testsolution (sample and standard) have the same concentration (ora known concentration) of an internal standard element that isnot present in the original sample. The internal standard isusually combined with the dilution solvent. Internal standardcompensation is typically handl
33、ed in one of two different ways,summarized as follows:8.1.1 Calibration curves are based on the measured intensityof each analyte divided (that is, scaled) by the measuredintensity of the internal standard per unit internal standard3Bansal, J. G., and McElroy, F. C., SAE Paper 932694, October 1993.
34、Availablefrom Society of Automotive Engineers (SAE), 400 Commonwealth Dr., Warrendale,PA 15096-0001.4Fluoroelastomer copolymer is manufactured as Viton, a trademark owned by E.I. duPont de Nemours.5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC.
35、 For suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D7040042element conc
36、entration. Concentrations for each analyte in thetest specimen solution are read directly from these calibrationcurves.8.1.2 For each analyte and the internal standard element,calibration curves are based on measured (unscaled) intensi-ties. Uncorrected concentrations for each analyte in the testspe
37、cimen solution are read from these calibration curves.Corrected analyte concentrations are calculated by multiplyingthe uncorrected concentrations by a factor equal to the actualinternal standard concentration divided by the uncorrectedinternal standard concentration determined by analysis.8.2 Disso
38、lve the organometallic compound representing theinternal standard in dilution solvent and transfer to a dispensingvessel. The stability of this solution shall be monitored andprepared fresh (typically weekly) when the concentration of theinternal standard element changes significantly. The concen-tr
39、ation of internal standard element shall be at least 100 timesits detection limit. A concentration in the range of 10 to 20mg/kg is typical.NOTE 1This test method specifies that the internal standard iscombined with the dilution solvent because this technique is common andefficient when preparing ma
40、ny samples. However, the internal standardcan be added separately from the dilution solvent as long as the internalstandard concentration is constant or accurately known.9. Sampling9.1 The objective of sampling is to obtain a test specimenthat is representative of the entire quantity. Thus, take lab
41、ora-tory samples in accordance with the instructions in PracticeD 4057. The specific sampling technique can affect the accu-racy of this test method.10. Preparation of Apparatus10.1 InstrumentDesign differences between instruments,ICP excitation sources, and different selected analytical wave-length
42、s for individual spectrometers make it impractical todetail the operating conditions. Consult the manufacturersinstructions for operating the instrument with organic solvents.Set up the instrument for use with the particular dilutionsolvent chosen.10.2 Peristaltic PumpInspect the pump tubing and re-
43、place it, if necessary, before starting each day. Verify thesolution uptake rate and adjust it to the desired rate.10.3 ICP Excitation SourceInitiate the plasma source atleast 30 min before performing an analysis. During thiswarm-up period, nebulize the dilution solvent. Inspect the torchfor carbon
44、buildup during the warm-up period. If carbonbuildup occurs, replace the torch immediately and consult themanufacturers operating guide to take proper steps to remedythe situation.NOTE 2Carbon that accumulates on the tip of the torch injector tubecan be removed by using nebulizer gas that consists of
45、 approximately 1 %oxygen in argon.10.3.1 Generally, carbon buildup can be minimized byincreasing the intermediate argon flow rate or lowering thetorch, or both, relative to the load coil.NOTE 3Some manufacturers recommend even longer warm-up peri-ods to minimize changes in the slopes of the calibrat
46、ion curves.10.4 Wavelength ProfilingPerform any wavelength profil-ing that is specified in the normal operation of the instrument.10.5 Operating ParametersAssign the appropriate oper-ating parameters to the instrument task file so that the desiredelements can be determined. Parameters to be included
47、 areelement, wavelength, background correction points (required),interelement correction factors (refer to 5.1), integration time,and internal standard compensation (required). Multiple inte-grations (typically three) are required for each measurement. Atypical integration time is 10 s.11. Preparati
48、on of Test Specimens11.1 DiluentDiluent refers to the dilution solvent contain-ing the internal standard (refer to 8.2).11.2 Test specimen solutions are prepared in the same waythat calibration standards are prepared (refer to 12.2). Themass % oil in diluent shall be the same for calibrationstandard
49、s and test specimen solutions.11.2.1 Lubricating Oil SpecimensWeigh appropriateamount of the test specimen to the nearest 0.001 g. The weightof the test specimen taken will vary depending upon the metalconcentration of the specimen. Dilute by mass with the diluent.Mix well.11.3 Record all weights and calculate dilution factors bydividing the sum of the weights of the diluent, sample, and baseoil (if any) by the weight of the sample.11.4 The user of this test method has the option of selectingthe dilution factor, that is, the relative amounts of sample anddiluent.
