1、Designation: D4951 09D4951 14Standard Test Method forDetermination of Additive Elements in Lubricating Oils byInductively Coupled Plasma Atomic Emission Spectrometry1This standard is issued under the fixed designation D4951; the number immediately following the designation indicates the year oforigi
2、nal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript 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 o
3、f Defense.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 solv
4、ent is held constant in the range of 1to 5 mass % oil.1.3 The precision tables define the concentration ranges covered in the interlaboratory study. However, both lower and higherconcentrations can be determined by this test method. The low concentration limits are dependent on the sensitivity of th
5、e ICPinstrument and the dilution factor. The high concentration limits are determined by the product of the maximum concentrationdefined 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
6、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 responsibilityof the user of this standard to establish appropriate safe
7、ty and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1552 Test Method for Sulfur in Petroleum Products (High-Temperature Method)D4057 Practice for Manual Sampling of Petroleum and Petroleum ProductsD4307 Practice fo
8、r Preparation of Liquid Blends for Use as Analytical StandardsD4628 Test Method for Analysis of Barium, Calcium, Magnesium, and Zinc in Unused Lubricating Oils by Atomic AbsorptionSpectrometryD4927 Test Methods for Elemental Analysis of Lubricant and Additive ComponentsBarium, Calcium, Phosphorus, S
9、ulfur,and Zinc by Wavelength-Dispersive X-Ray Fluorescence SpectroscopyD5185 Test Method for Multielement Determination of Used and Unused Lubricating Oils and Base Oils by InductivelyCoupled Plasma Atomic Emission Spectrometry (ICP-AES)D6299 Practice for Applying Statistical Quality Assurance and C
10、ontrol Charting Techniques to Evaluate Analytical Measure-ment System Performance3. Summary of Test Method3.1 A sample portion is weighed and diluted by mass with mixed xylenes or other solvent. An internal standard, which isrequired, is either weighed separately into the test solution or is previou
11、sly combined with the dilution solvent. Calibrationstandards are prepared similarly. The solutions are introduced to the ICP instrument by free aspiration or an optional peristaltic1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants a
12、nd is the direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved April 15, 2009Oct. 1, 2014. Published May 2009October 2014. Originally approved in 1989. Last previous edition approved in 20062009 asD4951D4951 09.06. DOI: 10.1520/D4951-09.10.1520/D4951-14.2 For re
13、ferencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide
14、 the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit 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 versionof the sta
15、ndard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1pump. By comparing emission intensities of elements
16、in the test specimen with emission intensities measured with the calibrationstandards and by applying the appropriate internal standard correction, the concentrations of elements in the sample are calculable.4. Significance and Use4.1 This test method usually requires several minutes per sample. Thi
17、s test method covers eight elements and thus providesmore elemental composition data than Test Method D4628 or Test Methods D4927. In addition, this test method provides moreaccurate results than Test Method D5185, which is intended for used lubricating oils and base oils.4.2 Additive packages are b
18、lends of individual additives, which can act as detergents, antioxidants, antiwear agents, and soforth. 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 additi
19、ve 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 meetspecifications with respect to elemental composition.4.3 Several additive elements and their compounds are added
20、 to the lubricating oils to give beneficial performance (Table 1).5. Interferences5.1 SpectralThere are no known spectral interferences between elements covered by this test method when using the spectrallines listed in Table 12. However, if spectral interferences exist because of other interfering
21、elements or selection of other spectrallines, correct for the interference using the technique described in Test Method D5185.5.2 Viscosity Index Improver Effect EffectViscosity index improvers, which can be present in multigrade lubricating oils, canbias measurements. However, the biases can be red
22、uced to negligible proportion by using the specified solvent-to-sample dilutionand an internal standard.6. Apparatus6.1 Inductively-Coupled Plasma Atomic Emission SpectrometerEither a sequential or simultaneous spectrometer is suitable,if equipped with a quartz ICP torch and RF generator to form and
23、 sustain the plasma.6.2 Analytical Balance, capable of weighing to 0.001 g or 0.0001 g, with sufficient capacity to weigh prepared solutions.6.3 Peristaltic Pump, (Recommended) (Recommended)A peristaltic pump is strongly recommended to provide a constantflow of solution. The pumping speed must be in
24、 the range 0.5 to 3 mL/min. The pump tubing must be able to withstand at least6 h exposure to the dilution solvent. Fluoroelastomer copolymer3 tubing is recommended.6.4 Solvent Dispenser, (Optional) (Optional)A solvent dispenser calibrated to deliver the required weight of diluent can beadvantageous
25、. Ensure that solvent drip does not affect accuracy.6.5 Specimen Solution Containers , Containers, of appropriate size, glass or polyolefin vials or bottles, with screw caps.3 Fluoroelastomer copolymer is manufactured as Viton, a trademark owned by E. I. duPont de Nemours.TABLE 1 Lubricants and Addi
26、tive MaterialsElement Compound PerformanceBarium Sulfonates, phenates Detergent inhibitors, corrosion inhibitors, detergents, rust inhibitors, andATFBoron Inorganic borates and borate esters, borateddispersants and detergentsAnti-wear agents, anti-oxidant, deodorant, cutting oils, and brake fluidsCa
27、lcium Sulfonates, phenates Detergent inhibitors and dispersantsCopper Copper dithiophosphates Anti-wear agent and anti-oxidantMagnesium Sulfonates, phenates Detergent inhibitorsMolybdenum Dialkylithiophosphate, dialkyldithiocarbamate, othermolybdenum complexesFriction modifier additivesPhosphorus Di
28、thiophosphates, phosphates, and phosphites Anti-rusting agents, extreme pressure additives, and anti-wearSulfur Base oils, sulfonates, thiophosphates, polysulfides,and other sulfurized componentsDetergents, extreme pressure additives, and antiwearZinc Dialkyldithiophosphates, dithiocarbamates,phenol
29、ates, carboxylatesAnti-oxidant, corrosion inhibitors, anti-wear additives, detergents,crankcase oils, hypoid gear lubricants, aircraft piston engine oils, turbineoils, ATF, railroad diesel engine oils, and brake lubricantsD4951 1426.6 Vortexer, (Optional)Vortex the sample plus diluent mixture until
30、the sample is completely dissolved.6.7 Ultrasonic Homogenizer, OptionalAbath-type or probe-type ultrasonic homogenizer can be used to homogenizer the testspecimen.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is inte
31、nded that allreagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where suchspecifications are available.47.2 Base Oil, U.S.P. white oil, or a lubricating base oil that is free of analytes, having a viscosity at room temperature as closeas p
32、ossible to that of the samples to be analyzed. (WarningLubricating base oils can contain sulfur. For preparation of sulfurstandards and blending of additive packages, white oil is recommended.)7.3 Internal Standard, (Required) (Required)An oil-soluble internal standard element is required. The follo
33、wing internalstandards were successfully used in the interlaboratory study on precision: Ag, Be, Cd, Co (most common), La, Mn, Pb, Y.7.4 Organometallic StandardsMulti-element standards, containing known concentrations (approximately 0.1 mass %) of eachelement, can be prepared from the individual met
34、al concentrates. Refer to Practice D4307 for a procedure for preparation ofmulticomponent liquid blends. When preparing multi-element standards, be certain that proper mixing is achieved. Commerciallyavailable multi-element blends (with known concentrations of each element at approximately 0.1 mass
35、%) 0.1 mass %) are alsosatisfactory.7.4.1 More than one multi-element standard can be necessary to cover all elements, and the user of this test method can selectthe combination of elements and their concentrations in the multi-element standards. It can be advantageous to selectconcentrations that a
36、re typical of unused oils. However, it is imperative that concentrations are selected such that the emissionintensities measured with the working standards can be measured precisely (that is, the emission intensities are significantly greaterthan background) and that these standards represent the li
37、near region of the calibration curve. Frequently, the instrumentmanufacturer publishes guidelines for determining linear range.7.4.2 Some commercially available organometallic standards are prepared from metal sulfonates and therefore contain sulfur.For sulfur determinations, a separate sulfur stand
38、ard can be required. A sulfur standard can be prepared by blending NIST SRM1622 with white oil.7.4.3 Metal sulfonates can be used as a sulfur standard if the sulfur content is known or determined by an appropriate testmethod such as Test Method D1552.7.4.4 Petroleum additives can also be used as org
39、anometallic standards if their use does not adversely affect precision norintroduce significant bias.7.5 Dilution SolventMixed xylenes, o-xylene, and kerosine were successfully used in the interlaboratory study on precision.8. Internal Standardization (Required)8.1 The internal standard procedure re
40、quires that every test solution (sample and standard) have the same concentration (or aknown concentration) of an internal standard element that is not present in the original sample. The internal standard is usuallycombined with the dilution solvent. Internal standard compensation is typically hand
41、led in one of two different ways, which canbe summarized as follows.4 Reagent Chemicals, American Chemical Society Specifications Specifications, , American Chemical Society, Washington, DC. For suggestions on the testing of reagentsnot listed by the American Chemical Society, see Analar Standards f
42、or Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia andNational Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.TABLE 12 Elements Determined and Suggested WavelengthsAElement Wavelength, nmBarium 233.53, 455.40, 493.41BoronB 182.59, 249.68C
43、alcium 315.88, 317.93, 364.4, 422.67Copper 324.75Magnesium 279.08, 279.55, 285.21Molybdenum 202.03, 281.62PhosphorusB 177.51, 178.29, 213.62, 214.91, 253.40SulfurB 180.73, 182.04, 182.62Zinc 202.55, 206.20, 213.86, 334.58, 481.05A These wavelengths are only suggested and do not represent all possibl
44、e choices.B Wavelengths for boron, phosphorus, and sulfur below 190 nm require that a vacuum or inert gas purged optical path be used.D4951 1438.1.1 Calibration curves are based on the measured intensity of each analyte divided (that is, scaled) by the measured intensityof the internal standard per
45、unit internal standard element concentration. Concentrations for each analyte in the test specimensolution 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 concentrati
46、ons for each analyte in the test specimen solution are read from these calibration curves. Corrected analyteconcentrations are calculated by multiplying the uncorrected concentrations by a factor equal to the actual internal standardconcentration divided by the uncorrected internal standard concentr
47、ation determined by analysis.8.2 Dissolve the organometallic compound representing the internal standard in dilution solvent and transfer to a dispensingvessel.The stability of this solution must be monitored and prepared fresh (typically weekly) when the concentration of the internalstandard elemen
48、t changes significantly.The concentration of internal standard element shall be at least 100 times its detection limit.A concentration in the range of 10 to 2020 mg mg/kg kg is typical.NOTE 1This test method specifies that the internal standard is combined with the dilution solvent because this tech
49、nique is common and efficient whenpreparing many samples. However, the internal standard can be added separately from the dilution solvent as long as the internal standard concentrationis constant or accurately known.9. Sampling9.1 The objective of sampling is to obtain a test specimen that is representative of the entire quantity. Thus, take lab samplesin accordance with the instructions in Practice D4057. The specific sampling technique can affect the accuracy of this test method.10. Preparation of Apparatus10.1 InstrumentDesign differences between instrum
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