1、Designation: D 3635 01 (Reapproved 2005)Standard Test Method forDissolved Copper In Electrical Insulating Oil By AtomicAbsorption Spectrophotometry1This standard is issued under the fixed designation D 3635; the number immediately following the designation indicates the year oforiginal adoption or,
2、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.1. Scope1.1 This test method covers the determination of copper innew or used electrical ins
3、ulating oil of petroleum origin byatomic absorption spectrophotometry.1.2 The lowest limit of detectability is primarily dependentupon the method of atomization, but also upon the energysource, the fuel and oxidant, and the degree of electricalexpansion of the output signal. The lowest detectable co
4、ncen-tration is usually considered to be equal to twice the maximumvariation of the background. For flame atomization, the lowerlimit of detectability is generally in the order of 0.1 ppm or 0.1mg/kg. For non-flame atomization, the lower limit of detect-ability is less than 0.01 ppm.1.3 The values s
5、tated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety
6、and health practices and determine the applica-bility of regulatory limitations prior to use. See 5.4 for specificprecautionary statements.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 3487 Specification for Mineral Insulating Oil Used inElectric ApparatusD 5222
7、Specification for High Fire-Point Mineral ElectricalInsulating Oils3. Summary of Test Method3.1 The test specimen of oil is filtered and diluted with anappropriate organic solvent and analyzed in an atomic absorp-tion spectrophotometer. Alternate procedures are provided forinstruments employing flam
8、e and non-flame atomization. Con-centration is determined by means of calibration curves pre-pared from standard samples.4. Significance and Use4.1 Electrical insulating oil may contain small amounts ofdissolved metals derived either directly from the base oil orfrom contact with metals during refin
9、ing or service. Whencopper is present, it acts as a catalyst in promoting oxidation ofthe oil. This test method is useful for research for new oils andto assess the condition of service-aged oils. Considerationshould be given to the limits of detection outlined in the scope.5. Apparatus5.1 Volumetri
10、c flasks, 100-mL capacity.5.2 Membrane filter, 0.45 m.5.3 Burets, 5 and 50-mL capacity.5.4 Atomic Absorption SpectrophotometerThe instrumentshall have an atomizer, a spectral energy source, usuallyconsisting of a copper hollow cathode lamp, a monochromatorcapable of isolating the desired line of rad
11、iation, an adjustableslit, a photomultiplier tube or other photosensitive device as alight measuring and amplifying device, and a read-out mecha-nism for indicating the amount of absorbed radiation.WarningProper ventilation must be provided to removetoxic metal vapors.5.4.1 Instruments employing fla
12、me atomization require anebulizer assembly, burner head, and suitable pressure andflow regulating devices to maintain constant oxidant and fuelflow for the duration of the tests.5.4.1.1 Glass Syringe, 10-mL capacity.5.4.2 Instruments employing non-flame atomization requirea suitable pressure regulat
13、ing device to maintain an inertatmosphere.5.4.2.1 Graphite Furnace with background correction.5.4.2.2 Output Device, Printer or Strip Chart Recorder (ifpermanent record is required).5.4.2.3 Pipets, 1 and 5-L.6. Reagents6.1 Purity of ReagentsUse reagent grade chemicals in alltests.1This test method i
14、s under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids and Gases and is the direct responsibility of Subcom-mittee D27.03 on Analytical Tests.Current edition approved Oct. 1, 2005. Published November 2005. Originallyapproved in 1977. Last previous edition approved in 2001 as
15、D 3635 01.2For referenced ASTM standards, visit the ASTM website, 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 Driv
16、e, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto the requirements in Specification D 1193 for Reagent Water,Type 1.6.3 Nitric Acid (1:2)Add one volume of nitric aci
17、d(HNO3sp gr 1.42) to two volumes of water.6.4 New OilUnused oil of the same type as that beingtested, such as oil meeting the requirements of SpecificationD 3487 or as described in Specification D 5222.6.5 Methyl Isobutyl Ketone (MIBK).6.6 Bis (1-phenyl-1, 3-butanediono) copper (II)NationalInstitute
18、 of Standards and Technology Metallo-Organic Com-pound No. 1080.36.7 Oxidant-Air, cleaned and dried through a suitable filterto remove oil, water, and other foreign substances.6.8 Acetylene, atomic absorption grade (Note 1).6.9 Argon, commercial grade.NOTE 1Acetylene cylinders should be replaced whe
19、n the pressurereaches 700 kPa (;100 psi) to prevent acetone, always present, fromentering and damaging the burner head.7. Preparation of Glassware7.1 Wash all glassware thoroughly, rinse with HNO3(1:2),and then with distilled water. Dry thoroughly.8. Procedure AFlame Atomization8.1 Preparation of St
20、andard Copper Solution (500 ppmCu):8.1.1 Dissolve 0.3030 g of NIST Standard No. 1080, bis(1-phenyl-1, 3-butanediono) copper (II), according to instruc-tions received with the standard, and dilute to 100.0 6 0.1 gwith new oil to make a 500 ppm standard copper solution.Shake well.8.2 Preparation of Wo
21、rking Standards:8.2.1 Dilute 2.00 g of the standard copper solution to 100mL with new oil to give an intermediate standard containingapproximately 10 g/mL Cu. This working standard containsthe 10 g/mL Cu added plus any copper present in the new oilused to make the standard. If the copper content of
22、the new oilis not known, it must be determined. When detectable levels ofcopper are suspected in the new oil or the copper content issimply unknown, refer to 8.4.1.5.8.2.2 Add to new oil aliquots of 10 g/mL Cu solution so asto obtain four standards containing additions of 0.0, 0.5, 1.0,and 3.0 g/mL
23、Cu; dilute each with MIBK to obtain an oil toketone ratio of 10 % (V/V) as follows (Note 2):WorkingStandard10 g/mL Custandard, mLNew Oil, mL MIBK, mLNo. 1 (blank) 0.0 10.0 90No. 2 0.5 9.5 90No. 3 1.0 9.0 90No. 4 3.0 7.0 90NOTE 2The new oil used to make these dilutions must be the samenew oil used to
24、 make the 10 g/mL standard. Good transfers can beeffected if a 50-mL buret is used for the new oil and a 5-mL buret is usedfor the 10 g/mL Cu standard. Do not transfer the solutions too rapidly.48.2.3 Shake well after dilution with MIBK.8.3 Preparation of Test Specimen:8.3.1 Filter the test specimen
25、 using a 0.45 m filter.8.3.2 Using a 10-mL glass syringe, transfer 10 mL of thefiltered test specimen to a 100-mL volumetric flask. Dilute tovolume with MIBK and shake well (Note 3).NOTE 3If a test specimen has a copper concentration greater than therange of the working standards, a more accurate re
26、sult can be obtained bydiluting a small aliquot of the test specimen with appropriate addition ofnew oil and MIBK to keep the 10 % oil to ketone ratio and rerunningagainst the working standards.8.4 Spectrophotometric Measurement:8.4.1 Operate the atomic absorption spectrophotometer ac-cording to the
27、 manufacturers instructions for the determina-tion of copper with the following exceptions and additions:8.4.1.1 Set the auxiliary air at twice the aspirating air if thisis within the range of instrument parameters.8.4.1.2 For narrow slit burners, reduce flow as low aspossible while maintaining the
28、flame on the burner head. Forthree slit burners, reduce fuel flow as low as possible whileaspirating neat MIBK so that orange streaks rising from therivet heads are still visible in the flame.8.4.1.3 Adjust the aspiration rate for maximum absorbancewhile burning No. 4 working standard.8.4.1.4 Set th
29、e instrument at zero absorbance while burningNo. 1 working standard.8.4.1.5 Set the instrument at zero absorbance while burningmethyl isobutyl ketone (MIBK). Plot a standard curve ofabsorbance versus copper concentration for standardsNos. 14. Extrapolate this curve to zero absorbance. Theabsolute va
30、lue of the copper concentration at zero absorbance(a negative number) provides an estimate of the coppercontained in the standard oil.8.4.2 Run the standards and test specimen in the followingorder: standards, test specimen, standards, test specimen, andstandards.9. Calculation and Report9.1 Average
31、 the readings, and if the scale was expanded,divide the averages by the scale expansion factor and convertto absorbances. Subtract the absorbance of the No. 1 workingstandard as a blank from the absorbances of the other standardsand test specimens and plot versus copper added.9.2 Calculate the coppe
32、r concentration, in parts per million,as follows:Copper, ppm 5Adwhere:3Available from the Office of Standard Reference Materials, U.S. Department ofCommerce, National Institute of Standards and Technology, Washington, DC 20234.4The sole source of supply of dilutors known to the committee at this tim
33、e isLabindustries, 1802 2nd St., Berkeley, CA 94710. If you are aware of alternativesuppliers, please provide this information to ASTM International Headquarters.Your comments will receive careful consideration at a meeting of the responsibletechnical committee,1which you may attend.D 3635 01 (2005)
34、2A = copper concentration of the test specimen solutiondetermined from the concentration plot, g/mL andd = density of the test specimen, g/mL.9.3 Report the results to the nearest 0.1 ppm.10. Precision and Bias10.1 It is not possible to specify the precision of ProcedureA in Test Method D 3635 for m
35、easuring dissolved copper inelectrical insulating oil because of the difficulty in arranging around-robin test with a large-enough sample of participatinglaboratories. Attempts continue to be made to locate a labora-tory capable of providing data from which the repeatability ofthis procedure can be
36、estimated.10.2 No information can be presented on the bias of TestMethod D 3635, Procedure A, because no material having anaccepted reference value of copper in electrical insulating oilhas been made available from a standards organization. Fur-thermore, the responsible subcommittee has been unable
37、as ofyet to attract volunteers for an interlaboratory study.11. Procedure BNon-Flame Atomization11.1 Preparation of Standard Copper Solution (500 ppmCu):11.1.1 Follow 8.1 in Procedure A.11.2 Preparation of Working Standards:11.2.1 Follow 8.2.1 in Procedure A.11.2.2 Add to new oil aliquots of the 10
38、g/mL Cu solutionso as to obtain five intermediate standards containing additionsof 0.00, 0.05, 0.10, 0.50, and 1.00 g/mL copper, respectively.Dilute each with MIBK to obtain an oil to ketone ratio of 10 %(V/V) as follows (Note 2):WorkingStandard10 g/mL CuStandard, mLNew Oil, mL MIBK, mLNo. 1 (blank)
39、 0.00 10.0 90No. 2 0.05 9.95 90No. 3 0.10 9.90 90No. 4 0.50 9.50 90No. 5 1.00 9.00 9011.2.3 Shake the standard solutions well after dilution withMIBK.11.3 Preparation of Test Specimens:11.3.1 Prepare samples as indicated in 8.3 (Note 3).11.4 Set up the graphite furnace atomic absorption spectro-phot
40、ometer for oil test specimens. A 5-L sample size can beused for the above standard solutions. Operate the spectropho-tometer according to the manufacturers instructions with thefollowing exceptions and additions.11.4.1 The following decontamination (instrument blank)and test specimen run parameters
41、have been found satisfactory.NOTE 4The temperatures achieved by control settings are onlyapproximate and may vary with individual instruments.Decontamination RunCycle Control SettingDry cycle = 5 s, 150CAsh cycle = 10 s, 550CAtomize cycle = 4 s, 2500CTest Specimen RunCycle Control SettingDry cycle =
42、 5 s, 150CAsh cycle = 10 s, 550CAtomize cycle = 4 s, 2500C11.4.1.1 Record a decontamination run. If no signal isrecorded above the noise level, make a run of the blank oil testspecimen. If a signal is obtained on the decontamination run,repeat it. If a signal still persists, increase the atomize cyc
43、letemperature to 2700C and repeat the run. If a signal stillpersists, refer to the instrument manual.11.4.2 Once a decontamination run has been obtained withno spurious signals, obtain triplicate absorbance values foreach standard used.11.4.3 When an unknown test specimen signal is brought onscale a
44、ccording to the manufacturers recommendation, obtaintriplicate absorbance values for each test specimen.12. Calculation and Report12.1 Plot the absorbance versus the copper added (g/mL)to the standards in 11.2. The negative value of the concentra-tion intercept represents the copper concentration in
45、 the new oilused to prepare these standards and in the MIBK used to dilutethem.12.2 Calculate the copper concentration in the test speci-mens as indicated in 9.2.12.3 Report the results to the nearest 0.01 ppm.13. Precision and Bias13.1 It is not possible to specify the precision of ProcedureB in Te
46、st Method D 3635 for measuring dissolved copper inelectrical insulating oil because of the difficulty in arranging around-robin test with a large enough sample of participatinglaboratories. An estimate of the repeatability has been devel-oped based on data supplied by a single laboratory. These data
47、are presented in Appendix X1. These results suggest that the95 % repeatability limit for copper content is 8.5 % of the testresult or approximately 1 ppb, when the mean copper level is10 ppb.13.2 No information can be presented on the bias of TestMethod D 3635, Procedure B, because no material havin
48、g anaccepted reference value of copper in electrical insulating oilhas been made available from a standards organization. Fur-thermore, the responsible subcommittee has been unable toattract enough volunteers for a valid interlaboratory study.14. Keywords14.1 atomic absorption; copper; electrical in
49、sulating oil;spectroscopyD 3635 01 (2005)3APPENDIX(Nonmandatory Information)X1. REPEATABILITY DATA ESTIMATE FOR A SINGLE LABORATORY TEST SERIES OF ANALYSESX1.1 Data are given from a single laboratory for themeasurement of the copper content of two oil samples used asquality control standards which contained copper at knownlevels. The test results are from two series of test results on twostandards on separate dates and are presented in Table X1.1.These determinations were made using Procedure B of TestMethod D 3635.ASTM International takes no
