1、Designation: D7151 05D7151 13Standard Test Method forDetermination of Elements in Insulating Oils by InductivelyCoupled Plasma Atomic Emission Spectrometry (ICP-AES)1This standard is issued under the fixed designation D7151; 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.1. Scope1.1 This test method describes the determination of metals and conta
3、minants in insulating oils by inductively coupled plasmaatomic emission spectrometry (ICP-AES). The specific elements are listed in Table 1. This test method is similar to Test MethodD5185, but differs in methodology, which results in the greater sensitivity required for insulating oil applications.
4、1.2 This test method uses oil-soluble metals for calibration and does not purport to quantitatively determine insolubleparticulates. Analytical results are particle size dependent, and low results are obtained for particles larger than severalmicrometers.21.3 This test method determines the dissolve
5、d metals (which maycan originate from overheating) overheating or arcing, or both)and a portion of the particulate metals (which generally originate from a wear mechanism). While this ICP method detects nearlyall particles less than several micrometers, the response of larger particles decreases wit
6、h increasing particle size because largerparticles are less likely to make it through the nebulizer and into the sample excitation zone.1.4 This test method includes an option for filtering the oil sample for those users who wish to separately determine dissolvedmetals and particulate metals (and he
7、nce, total metals).1.5 Elements present at concentrations above the upper limit of the calibration curves can be determined with additional,appropriate dilutions and with no degradation of precision.1.6 The values stated in SI (metric) units are to be regarded as the standard. The inch-pound units g
8、iven in parentheses are forinformation only.No other units of measurement are included in this standard.1.7 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
9、health practices and to determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3C1109 Practice for Analysis of Aqueous Leachates from Nuclear Waste Materials Using Inductively Coupled Plasma-AtomicEmission SpectroscopyD923 Practices for Sampling E
10、lectrical Insulating LiquidsD1744 Test Method for Water in Liquid Petroleum Products by Karl Fischer Reagent4D2864 Terminology Relating to Electrical Insulating Liquids and GasesD4307 Practice for Preparation of Liquid Blends for Use as Analytical StandardsD5185 Test Method for Multielement Determin
11、ation of Used and Unused Lubricating Oils and Base Oils by InductivelyCoupled Plasma Atomic Emission Spectrometry (ICP-AES)1 This test method is under the jurisdiction of ASTM Committee D27 on Electrical Insulating Liquids and Gases and is the direct responsibility of SubcommitteeD27.03on Analytical
12、 Tests.Current edition approved May 1, 2005Nov. 1, 2013. Published June 2005November 2013. Originally approved in 2005. Last previous edition approved in 2005 asD7151-05. DOI: 10.1520/D7151-05.10.1520/D7151-13.2 Eisentraut, K. J., Newman, R. W., Saba, C. S., Kauffman, R. E., and Rhine, W. E., Analyt
13、ical Chemistry, Vol 56, 1984.3 For referencedASTM 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.4 Withdrawn. The last approved v
14、ersion of this historical standard is referenced on www.astm.org.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. Becauseit may not be technically possible to adequately depict all
15、 changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-295
16、9. United States13. Terminology3.1 Definitions for general terms may be are found in Terminology D2864.3.2 Definitions of Terms Specific to This Standard:3.2.1 Babington-type nebulizernebulizer, na device that generates an aerosol by flowing a liquid over a surface that containsan orifice from which
17、 gas flows at a high velocity.3.2.2 inductively-coupled plasma (ICP)(ICP), na high-temperature discharge generated by flowing an ionizable gas througha magnetic field induced by a load coil that surrounds the tubes carrying the gas.3.2.3 linear response rangerange, nthe elemental concentration range
18、 over which the calibration curve is a straight line,within the precision of the test method.3.2.4 profilingprofiling, na technique that determines the wavelength for which the signal intensity measured for a particularanalyte is a maximum.3.2.5 wear metalmetal, nan element introduced into the oil b
19、y wear of oil-wetted parts.3.2.6 dissolved metalmetal, na metallic element in the oil which will pass a 0.45 m filter.4. Summary of Test Method4.1 A weighed portion of a thoroughly homogenized insulating oil is diluted 2.5:1 by weight with kerosine or other suitablesolvent. Standards are prepared in
20、 the same manner. An internal standard is may be added to the solutions to compensate forvariations in test specimen introduction efficiency.The solutions are may be introduced to the ICPinstrument by a peristaltic pump.If free aspiration is used, an internal standard mustshall be used. By comparing
21、 emission intensities of elements in the test specimenwith emission intensities measured with the standards, the concentrations of elements in the test specimen are calculated.5. Significance and Use5.1 This test method covers the rapid determination of 12 elements in insulating oils, and it provide
22、s rapid screening of usedoils for indications of wear. Test times approximate several minutes per test specimen, and detectability is in the 10-100 10 through100 g/kg range.5.2 This test method can be used to monitor equipment condition and help to define when corrective action is needed. It canalso
23、 be used to detect contamination such as from silicone fluids (via Silicon) or from dirt (via Silicon and Aluminum).5.3 This test method can be used to indicate the efficiency of reclaiming used insulating oil.6. Interferences6.1 SpectralCheck all spectral interferences expected from the elements li
24、sted in Table 1. Follow the ICP manufacturersoperating guide to develop and apply correction factors to compensate for the interferences. To apply interference corrections, allconcentrations must be within the previously established linear response range of each element listed in Table 1.6.1.1 Spect
25、ral interferences can usually be avoided by judicious choice of analytical wavelengths. When spectral interferencescannot be avoided, the necessary corrections shouldshall be made using the computer software supplied by the ICP manufactureror the empirical method given in Test Method C1109 or by Bou
26、mans.55 Boumans, P. W .J. M., “Corrections for Spectral Interferences in Optical Emission Spectroscopy with Special Reference to the RF Inductively Coupled Plasma,”Spectrochimica Acta, 1976, Vol 318, pp. 147-152.TABLE 1 Elements Determined and Suggested WavelengthsAElement Wavelength, nmAluminum 308
27、.22, 396.15, 309.27Cadmium 226.50. 214.44Cobalt 228.62 231.16Copper 324.75Iron 259.94, 238.20Lead 220.35Nickel 231.60, 227.02, 221.65Scandium 361.38Silicon 288.16, 251.61Silver 328.07Sodium 589.59Tin 189.99, 242.95Tungsten 239.71Yttrium 371.03Zinc 206.20, 202.55, 213.86, 334.58, 481.05AThese wavelen
28、gths are only suggested and do not represent all possible choices.D7151 1326.1.2 Interference correction factors can be negative if off-peak background correction is employed for an element. A negativecorrection factor can result when an interfering line is encountered at the background correction w
29、avelength rather than at the peakwavelength.6.2 Viscosity EffectsDifferences in the viscosities of the test specimen solutions and standard solutions can cause differencesin the uptake rates. These differences can adversely affect the accuracy of the analysis. The effects can be reduced by using ape
30、ristaltic pump to deliver solutions to the nebulizer or by the use of internal standardization, or both.6.3 ParticulatesThe use of an internal standard will reveal when particulates cause flow problems. Use of a Babington-typehigh-solids nebulizer helps to minimize plugging of the nebulizer. Also, t
31、he specimen introduction system can limit the transportof particulates, and the plasma can incompletely atomize larger particulates, thereby causing low results.6.4 Solvent MoistureExcessive moisture (30 mg/kg) in the kerosine used for dilution can cause poor recovery of someelements. This can be mi
32、nimized by checking each lot of kerosine for moisture content using Test Method D1744 and by analyzingall diluted standards and test specimens within 24 h of preparation.7. Apparatus7.1 Balance, top loading, with automatic tare, capable of weighing to 0.001g, capacity of at least 150 g. A balance wi
33、th acapacity of at least 250 g is required if preparing the Internal Standard according to 10.2.7.2 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 maintain the plasma
34、. Suggested wavelengths for thedetermination of the elements in insulating oil are given in Table 1.7.3 NebulizerUse the nebulizer recommended by the ICP manufacturer. A Babington-type high-solids nebulizer mayshouldbe usefulused if samples contain high solids. This type of nebulizer reduces the pos
35、sibility of clogging and minimizes aerosolparticle effects.7.4 Peristaltic PumpPump, (optional)Aperistaltic pump is required may be used to provide a constant flow of solution. Thepump tubing mustshall be able to withstand at least 6 h exposure to the dilution solvent. Viton tubing is typically used
36、 withhydrocarbon solvents, and poly (vinyl chloride) tubing is typically used with methyl isobutyl ketone.7.5 Solvent Dispenser,Dispenser (optional),(optional) Asolvent dispenser calibrated to deliver the required weight of dilutionsolvent is very useful. This dispenser shouldshall have at least 1 %
37、 accuracy and 0.1 % precision.7.6 Internal Standard Dispenser , (optional),(Optional) A dispenser calibrated to deliver the required weight of internalstandard solution is very useful. This dispenser shouldshall have at least 1 % accuracy and 0.1 % precision.7.7 Specimen Solution Containers , Contai
38、ners, nominal 30 mL (1 oz.), 30-mL glass or plasticpolyethylene vials, with screwcaps or snap-top caps.8. 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 C
39、ommittee on Analytical Reagents of the American Chemical Society where suchspecifications are available.6 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purityto permit its use without introducing a significant source of error.lessening the accura
40、cy of determination.8.2 Base OilU.S.P. White oil or any mineral oil that is free of analytes and having a viscosity at room temperature as closeas possible to that of the samples to be analyzed.8.3 Dilution SolventReagent grade kerosine is recommended as a dilution solvent.Another solvent (such as t
41、oluene or xylene)may be used if it is free of all analytes and completely dissolves all standards and samples.8.4 Internal StandardOil-soluble scandium, cobalt, or yttrium is required when the internal standardization option is selected.8.5 Organometallic StandardsMulti-element standards, containing
42、 3.0 and 10.0 g/g of each element, can be purchased orprepared from the individual concentrates. Refer to Practice D4307 for a procedure for preparation of multicomponent liquidblends. When preparing multi-element standards, an ultrasonic bath is recommended to ensure that complete mixing is achieve
43、d.It is highly recommended to purchase the standards because of the difficulty in preparing multi-element standards.8.5 Dilution SolventReagent grade kerosine is recommended as a dilution solvent.Another solvent (such as toluene or xylene)may be used if it is free of all analytes and completely diss
44、olves all standards and samples.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 AnnualAnalar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dors
45、et, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D7151 1339. Hazards9.1 Kerosine is classified as a combustible liquid and must be kept away from all ignition sources. If the ICP is allowed tooperate unattended, equipment m
46、alfunctions could cause leakage of kerosine.10. Internal Standardization10.1 The internal standard procedure requires that every test specimen solution have the same concentration of an internalstandard element that is not present in the original specimen. Specimen to specimen changes in the emissio
47、n intensity of theinternal standard element can be used to correct for variations in the test specimen introduction efficiency, which is dependent onthe physical properties of the test specimen.10.2 Internal Standard Solution Weigh 25.0 6 0.1g of 2000 g/g scandium-in-oil (or cobalt- or yttrium-in-oi
48、l) standard intoa 500-mL Erlenmeyer flask. Add kerosine to make a total of 250 6 1 g. Mix this solution thoroughly and transfer to the reservoirfor the internal standard container or dispenser. The concentration of the internal standard is not required to be 200 g/g. However,the concentration of the
49、 internal standard element should be at least 100 times its detection limit.11. Sampling and Sample Handling11.1 Laboratory samples must be taken in accordance with the instructions in Practices D923.11.2 It is important to homogenize the insulating oil in the sample container in order to obtain a representative test specimen.Mix the insulating oil sample vigorously by inverting several times.11.3 (Optional) To separately determine the dissolved metals and particulate metals, filter the oil sample through a 0.45 mfilter. The particles on the
