1、Designation: D4952 12 (Reapproved 2017)Standard Test Method forQualitative Analysis for Active Sulfur Species in Fuels andSolvents (Doctor Test)1This standard is issued under the fixed designation D4952; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he 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 of Defense.1. Scope1.1
3、 This test method covers and is intended primarily for thedetection of mercaptans in motor fuel, kerosine, and similarpetroleum products. This method may also provide informationon hydrogen sulfide and elemental sulfur that may be present inthese sample types.1.2 The values stated in SI units are to
4、 be regarded asstandard. No other units of measurement are included in thisstandard.1.3 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 and health practices and
5、 determine the applica-bility of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-m
6、endations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD3227 Test Method for (Thiol Mercaptan) Sulfur inGasoline, Kerosine, Aviation Turbine, and Distillate Fuels(Potentiometric Metho
7、d)2.2 Energy Institute Standards:3IP 30 Detection of Mercaptans, Hydrogen Sulfide, ElementalSulfur, and Peroxides Doctor Test Method3. Summary of Test Method3.1 The sample is shaken with sodium plumbite solution, asmall quantity of powdered sulfur added, and the mixtureshaken again. The presence of
8、mercaptans or hydrogen sulfideor both is indicated by discoloration of the sulfur floating at theoil-water interface or by discoloration of either of the phases.4. Significance and Use4.1 Sulfur present as mercaptans or as hydrogen sulfide indistillate fuels and solvents can attack many metallic and
9、non-metallic materials in fuel and other distribution systems. Anegative result in the doctor test ensures that the concentrationof these compounds is insufficient to cause such problems innormal use.5. Interferences5.1 This test cannot be used if there are more than traceamounts of peroxides in the
10、 test sample. Peroxides can give afalse positive results where mercaptans are at low level or noteven present.45.2 To check if peroxides are present in sufficient concen-tration to invalidate the test, shake 10 mL 6 0.5 mL of a freshportion of the sample with approximately 2 mL of the potas-sium iod
11、ide solution, add two drops of the acetic acid solution,and two drops of the starch solution. If the aqueous layer turnsa blue color, this confirms the presence of peroxides insufficient quantity to invalidate the test, and the test on thissample should be discontinued. Proceed in accordance with5.4
12、.5.3 Alternatively, one may choose to perform a preliminaryDoctor Test. If a brown precipitate slowly forms, peroxide isprobably present. Proceed in accordance with 5.2 to confirmpresence of peroxides at sufficient quantity to invalidate thetest.5.4 If interference from peroxides is confirmed, proce
13、ed tore-sample and retest. Ensure that sampling and handlingprocedures for the new sample prevent UV light exposures as1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.03 on Elemen
14、tal Analysis.Current edition approved May 1, 2017. Published June 2017. Originallyapproved in 1989. Last previous edition approved in 2012 as D4952 12. DOI:10.1520/D4952-12R17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. Fo
15、r Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,U.K., http:/www.energyinst.org.4Brooks, B. T., “Sodium Plumbite or Doctor Test of Gasolines,” Industrial andEngin
16、eering Chemistry, Vol 16, No. 6, June 1924, p. 588.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the
17、 Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1prescribed in 7.1. None of the normal refinery units or blendingprocesses producing spark ignition motor fuels are kno
18、wn tocreate peroxides under normal operating conditions.6. Reagents and Materials6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American C
19、hemical Society wheresuch specifications are available.5Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.6.2 Purity of WaterUnless otherwise indicated, referencesto water shal
20、l be understood to mean reagent water as definedby Types II or III of Specification D1193.6.3 Doctor (Sodium Plumbite) Solution(WarningPoisonous and suspect carcinogen.) Dissolve approximately125 g of sodium hydroxide (NaOH) in 1 L of reagent water.Add 60 g of lead monoxide (PbO) and shake vigorousl
21、y for15 min, or let stand with occasional shakings for at least oneday. Allow to settle and decant or siphon off the clear liquid. Ifthe solution does not settle clear, filter it through filter paper.Keep the solution in a tightly sealed bottle and refilter beforeuse if not perfectly clear. As an al
22、ternative, the lab may use acommercially prepared solution that meets the requirements ofthe laboratory preparation.NOTE 1Alternative volumes of the solution may be prepared orpurchased, provided the final solution concentration is equivalent.6.4 SulfurPure, sublimed, stored in a closed container.6.
23、5 Potassium Iodide, approximately 100 g L SolutionDissolve approximately 1 g of potassium iodide in approxi-mately 10 mL of water. Prepare fresh for each test.6.6 Acetic Acid, approximately 100 g L SolutionAdd ap-proximately 10 mL of glacial acetic acid to approximately100 mL water.6.7 Starch Indica
24、tor, approximately 5 g L IndicatorSolutionPrepare fresh each time of testing.7. Sampling and Handling of Test Samples7.1 Improper choice of clear glass sample bottles followedby exposure to sunlight or fluorescent lighting emitting UVwavelengths shorter than 550 nm in the laboratory can generatepero
25、xides in cracked gasolines as well as finished batches ofgasolines. Peroxides are generated in proportion to the head-space air volume and time of exposure.6It has been reportedthat peroxides can interfere with the Doctor Testsee 5.1.7.2 It is preferable to collect the field samples using darkbrown/
26、amber bottles or metal cans, or if using clear glassbottles to wrap them in foil or place in a light-tight box toprevent UV light exposure.7.3 The samples should be tested without delay upon receiptin the laboratory before further chemical interactions takeplace.8. Procedure8.1 Shake vigorously toge
27、ther in a test tube 10 mL of thesample being tested and 5 mL of sodium plumbite solution forabout 15 s. Add a small amount of pure, sublimed flowers ofsulfur so that practically all of it floats on the interface betweenthe sample and the sodium plumbite solution after shaking.Shake again for 15 s. A
28、llow to settle and observe within 2 min.NOTE 2It is important to avoid adding more sulfur than will just coverthe interface. About 20 mg to 25 mg is the proper quantity, which can beestimated with a little practice. If too much sulfur is added, any possiblediscoloration will be masked by the excess
29、of sulfur.9. Interpretation of Results9.1 If the solution is discolored or if the yellow color of thesulfur film is noticeably masked, report the test as positive andconsider the sample as sour. If the sample remains unchangedin color and the sulfur film is bright yellow or only slightlydiscolored w
30、ith gray or flecked with black, report the test asnegative and consider the sample as sweet. If a brownprecipitate slowly forms, peroxide is probably present. Proceedin accordance with 5.2.NOTE 3This examination must be made with extreme care. Some-times the sulfur layer will be only flecked with sp
31、ots of gray or black, andif there is any change in the color of either the sample or the Doctorsolution these spots will be difficult to detect.NOTE 4Strictly speaking, the test will not reject the sample on thebasis of mercaptans only. The primary criterion for rejection is theappearance of the sul
32、fur layer after shaking, and small amounts ofmercaptans will only discolor the sulfur. However, samples which containmercaptans will also normally contain small amounts of sulfur in otherforms which will discolor the layers at the interface. The addition of pure,sublimed flowers of sulfur is require
33、d to indicate that a reaction ofmercaptan and sodium plumbite has occurred.NOTE 5When the sample contains appreciable amounts of hydrogensulfide, a heavy black precipitate may be formed during the initial shakingand before the addition of the sulfur. If such a precipitate is noted, the testmay be st
34、opped at that point and the sample reported as “Does not pass.”However, if this observation is at all doubtful, the test should becontinued. If the sample darkens before the addition of sulfur is made, thisindicates that the sample contains mercaptans and an excess of elementalsulfur that is needed
35、to drive the sample reaction with sodium plumbite.9.1.1 The relationship between the appearance of thesample and the type of sulfur is shown in Table 1.9.2 If the doctor test is positive, mercaptan content may bedetermined using Test Method D3227.10. Precision and Bias10.1 No justifiable values of r
36、epeatability, reproducibility,or bias for this test method can be stated here because the testdetects only the presence or absence of active sulfur species,such as hydrogen sulfide or mercaptan.5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. Fo
37、r suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.6Supporting data (Jenni
38、ngs, R., and Kohler, D., “Sunlight and Air ExposureEffects on Octane Number or Cetane Number of Petroleum Product Samples,”April2001) have been filed at ASTM International Headquarters and may be obtained byrequesting Research Report RR:D02-1502. Contact ASTM Customer Service atserviceastm.org.D4952
39、 12 (2017)211. Keywords11.1 doctor test; hydrogen sulfide; kerosine; mercaptans;motor fuel; sulfurASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determ
40、ination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or w
41、ithdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that
42、your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (s
43、ingle or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright
44、 Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 1 Relationship Between Sample and SulfurAppearance Type of SulfurFormation of a brown precipitate before addition of sulfur Peroxide is probably present; proceed in accordance with 5.2Darkening of the sample before
45、addition of sulfur Mercaptans and elemental sulfur present in sampleBlack precipitate before addition of sulfur Appreciable amounts of hydrogen sulfideBlack color of sulfur after shaking Traces of hydrogen sulfideSpots of discoloration in the sulfur layer, plus darkening of the sample Hydrogen sulfide absent; mercaptans or elemental sulfur, or both, presentClear yellow Doctor solution; no discoloration of sulfur Hydrogen sulfide and elemental sulfur absent; traces of mercaptans presentD4952 12 (2017)3
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1