1、Designation: D7303 12D7303 17Standard Test Method forDetermination of Metals in Lubricating Greases byInductively Coupled Plasma Atomic Emission Spectrometry1This standard is issued under the fixed designation D7303; the number immediately following the designation indicates the year oforiginal adop
2、tion 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.1. Scope*1.1 This test method covers the determination of a number of metals such as
3、 aluminum, antimony, barium, calcium, iron,lithium, magnesium, molybdenum, phosphorus, silicon, sodium, sulfur, and zinc in unused lubricating greases by inductivelycoupled plasma atomic emission spectrometry (ICP-AES) technique.1.1.1 The range of applicability for this test method, based on the int
4、erlaboratory study conducted in 2005,2 is aluminum(10600), antimony (102300), barium (50800), calcium (2050 000), iron (10360), lithium (3003200), magnesium(3010 000), molybdenum (5022 000), phosphorus (502000), silicon (1015 000), sodium (301500), sulfur (160028 000), andzinc (3002200), (10 to 600)
5、, antimony (10 to 2300), barium (50 to 800), calcium (20 to 50 000), iron (10 to 360), lithium (300to 3200), magnesium (30 to 10 000), molybdenum (50 to 22 000), phosphorus (50 to 2000), silicon (10 to 15 000), sodium (30 to1500), sulfur (1600 to 28 000), and zinc (300 to 2200), all in mg/kg. Lower
6、levels of elements may be determined by using largersample weights, and higher levels of elements may be determined by using smaller amounts of sample or by using a larger dilutionfactor after sample dissolution. However, the test precision in such cases has not been determined, and may be different
7、 than theones given in Table 1.1.1.2 It may also be possible to determine additional metals such as bismuth, boron, cadmium, chromium, copper, lead,manganese, potassium, titanium, etc. by this technique. However, not enough data is available to specify the precision for theselatter determinations. T
8、hese metals may originate into greases through contamination or as additive elements.1.1.3 During sample preparation, the grease samples are decomposed with a variety of acid mixture(s). It is beyond the scopeof this test method to specify appropriate acid mixtures for all possible combination of me
9、tals present in the sample. But if the ashdissolution results in any visible insoluble material, the test method may not be applicable for the type of grease being analyzed,assuming the insoluble material contains some of the analytes of interest.1.2 Elements present at concentrations above the uppe
10、r limit of the calibration curves can be determined with additionalappropriate dilutions of dissolved samples and with no degradation of precision.1.3 The development of the technique behind this test method is documented by Fox.31.4 The values stated in SI units are to be regarded as the standard.
11、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 responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicabilit
12、y of regulatorylimitations prior to use. Specific warning statements are given in Sections 8 and 10.1.6 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International
13、Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.1 This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.
14、03 on Elemental Analysis.Current edition approved June 1, 2012June 1, 2017. Published August 2012June 2017. Originally approved in 2006. Last previous edition approved in 20062012 asD7303D7303 12.06. DOI: 10.1520/D7303-12.10.1520/D7303-17.2 Supporting data have been filed at ASTM International Headq
15、uarters and may be obtained by requesting Research Report RR:D02-1608. Contact ASTM CustomerService at serviceastm.org.3 Fox, B. S., “Elemental Analysis of Lubricating Grease by Inductively Coupled Plasm Atomic Emission Spectrometry (ICP-AES),” J. ASTM International, Vol 2, No.8, 2005, pp. 12966.Thi
16、s 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. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editio
17、ns as appropriate. In all cases only the current versionof the standard 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.
18、United States12. Referenced Documents2.1 ASTM Standards:4D1193 Specification for Reagent WaterD3340 Test Method for Lithium and Sodium in Lubricating Greases by Flame Photometer (Withdrawn 2013)5D4057 Practice for Manual Sampling of Petroleum and Petroleum ProductsD4951 Test Method for Determination
19、 of Additive Elements in Lubricating Oils by Inductively Coupled Plasma AtomicEmission SpectrometryD5185 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 Statist
20、ical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-ment System PerformanceD6792 Practice for Quality Management Systems in Petroleum Products, Liquid Fuels, and Lubricants Testing LaboratoriesD7260 Practice for Optimization, Calibration, and Validation of Inductive
21、ly Coupled Plasma-Atomic Emission Spectrometry(ICP-AES) for Elemental Analysis of Petroleum Products and Lubricants3. Terminology3.1 DefinitionsRefer to terminology identified in Test Method D5185 for spectroscopy terms used in this standard.4. Summary of Test Method4.1 A weighed portion of the grea
22、se sample is weighed and subjected to alternate means of sample dissolution which mayinclude sulfated ashing in a muffle furnace or by closed vessel microwave digestion in acid. Ultimately these diluted acid solutionsare analyzed using ICP-AES. Aqueous calibration standards are used. The solutions a
23、re introduced to the ICP instrument by freeaspiration or an optional peristaltic pump. By comparing emission intensities of elements in the test specimen with those measuredwith the calibration standards, the concentrations of elements in the test specimen can be calculated.4.2 Additional informatio
24、n on using inductively coupled plasma-atomic emission spectrometry can be found in Practice D7260.5. Significance and Use5.1 Lubricating greases are used in almost all bearings used in any machinery. Lubricating grease is composed of 90 %additized oil and soap or other thickening agent. There are ov
25、er a dozen metallic elements present in greases, either blended asadditives for performance enhancements or as thickeners, or in used greases present as contaminants and wear metals. Determiningtheir concentrations can be an important aspect of grease manufacture.The metal content can also indicate
26、the amount of thickenersin the grease. Additionally, a reliable analysis technique can also assist in the process of trouble shooting problems with new andused grease in the field.5.2 Although widely used in other sectors of the oil industry for metal analysis, ICP-AES based Test Methods D4951 or D5
27、185cannot be used for analyzing greases because of their insolubility in organic solvents used in these test methods. Hence, greasesamples need to be brought into aqueous solution by acid decomposition before ICP-AES measurements.4 For referencedASTM standards, visit theASTM website, www.astm.org, o
28、r contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.5 The last approved version of this historical standard is referenced on www.astm.org.TABLE 1 Precision of Grease AnalysisNOTE 1X i
29、s the mean concentration in mg/kg.Element Range,mg/kg Repeatability ReproducibilityAluminum 10600 0.2163 X0.9 6.8156 X0.9Antimony 102300 0.3051 X0.8191 4.6809 X0.8191Barium 50800 0.3165 X0.7528 2.9503 X0.7528Calcium 2050 000 2.2853 X0.7067 3.0571 X0.7067Iron 10360 0.8808 X0.7475 2.5737 X0.7475Lithiu
30、m 3003200 0.0720 X1.0352 0.1476 X1.0352Magnesium 3010 000 0.6620 X0.6813 2.6155 X0.6813Molybdenum 5022 000 0.1731 X0.9474 0.4717 X0.9474Phosphorus 502000 1.2465 X0.6740 4.0758 X0.6740Silicon 1015 000 1.3859 X0.9935 4.8099 X0.9935Sodium 301500 6.5760 X0.5 11.571 X0.5Sulfur 160028 000 1.0507 X0.8588 1
31、.5743 X0.8588Zinc 3002200 0.1904 X0.8607 0.5912 X0.8607D7303 1725.3 Test Method D3340 has been used to determine lithium and sodium content of lubricating greases using flame photometry.This technique is no longer widely used. This new test method provides a test method for multi-element analysis of
32、 grease samples.This is the first DO2D02 standard available for simultaneous multi-element analysis of lubricating greases.6. Interferences6.1 SpectralSpectral interferences can usually be avoided by judicious choice of analytical wavelengths. There are no knownspectral interferences between element
33、s covered by this test method when using the spectral lines listed in Table 2. However, ifspectral interferences exist because of other interfering elements or selection of other spectral lines, correct for the interferencesusing the technique described in Test Method D5185.6.1.1 Follow the instrume
34、nt manufacturers operating guide to develop and apply correction factors to compensate for theinterferences.6.2 ChemicalIf the grease sample contains refractory additives such as silicon or molybdenum, it is possible that some ofthese elements may remain undissolved in the residue, and may result in
35、 lower recoveries.6.2.1 If HF is used for dissolution of grease residues, elements such as silicon may be lost as SiF6. Residual HF can also attackthe ICP sample introduction system. HF can be passivated by adding dilute boric acid to the acid solution.6.2.2 If the dry ashing in sample preparation s
36、tep is used, elements such as sulfur will be volatilized during combustion.7. Apparatus7.1 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.7.2 Inductively Coupled Plasma Atomic Emission SpectrometerEither a sequential or simultaneous spect
37、rometer is suitable,if equipped with a quartz ICPtorch and RF generator to form and sustain the plasma. Suggested wavelengths for the determinationof elements in dissolved grease solutions are given in Table 2.7.3 Peristaltic Pump, (Recommended)Aperistaltic pump is strongly recommended to provide a
38、constant flow of solution. Thepumping speed must be in the range of 0.50.5 mLmin to 3 mLmin. The pump tubing must be able to withstand at least 6 hexposure to solutions.7.4 Specimen Solution Containers, of appropriate size, glass or polyolefin vials or bottles, with screw caps without metal liners.8
39、. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where suchspecifications are available.
40、6 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purityto permit its use without lessening the accuracy of the determination.8.2 Sulfuric Acid, concentrated sulfuric acid, H2SO4. (WarningCauses severe burns. Corrosive.)8.3 Nitric Acid, concentrate
41、d nitric acid, HNO3. (WarningCauses severe burns. Corrosive.)6 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals,
42、 BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulatory, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD.TABLE 2 Suggested WavelengthsA,B for Elements Determined inGrease SamplesElement Wavelength, nmAluminum 167.038, 308.22, 396.15, 309.27Antimony 206.8
43、3, 217.58, 231.15Barium 223.53, 233.527, 455.40, 493.41Calcium 315.88, 317.93, 364.4, 396.85, 422.67Iron 238.20, 259.94Lithium 670.78, 610.36, 460.29Magnesium 279.08, 279.55, 280.278, 285.21Molybdenum 135.387, 202.03, 281.62Phosphorus 177.51, 178.29, 213.62, 214.91, 253.40Silicon 288.16, 251.618Sodi
44、um 589.595Sulfur 182.04, 180.73, 182.63Zinc 202.55, 206.20, 213.86, 334.58, 481.05A These wavelengths are only suggested and do not represent all possiblechoices.B Wavelengths for boron, phosphorus, and sulfur below 190 nm require that avacuum or inert gas purge optical path be used.D7303 1738.4 Hyd
45、rochloric Acid, concentrated hydrochloric acid, HCl. (WarningCauses burns.)8.5 Hydrofluoric Acid, concentrated hydrofluoric acid, HF (WarningCauses severe burns.)8.6 Aqueous Standard Solutions, individual aqueous elemental standards with 100 mg/L concentrations of elements of interest.These can be p
46、repared by dissolving pure metal compounds in water or dilute acids, or may be purchased from commercialsources.8.6.1 Multi-element aqueous standards may be advantageous to use.8.6.2 Internal Standard, aqueous cobalt, indium, scandium, yttrium or other single element standard, not a component of the
47、grease test specimen or calibration standard, nominal 500 mg/kg concentration.8.7 Water, distilled or deionized water, unless otherwise indicated, references to water shall be understood to mean Type IIreagent grade water as defined in Specification D1193.8.8 Quality Control (QC) Samples, preferably
48、 are portions of one or more grease materials that are stable and representative ofthe samples of interest. These QC samples can be used to check the validity of the testing process as described in Section 15.8.9 Microwave Oven, commercially available laboratory microwave digestion oven of sufficien
49、t power (for example, at least1000 W) 1000 W) is suitable. The microwave digestion dishes are also commercially available. (WarningTake all necessaryprecautions to prevent exposure to radiofrequency radiation.)8.10 Microwave Sample Digestion System, with closed-vessel silicon-free polytetrafluoroethylene (PTFE) digestion vessels.The vessels need to be capable of withstanding the pressure generated from the digestion of 0.2 g 0.2 g of sample (pressureachieved with a 100 mL 100 mL vessel and 0.2 g 0.2 g of sample could be in excess of 10
