1、Designation: D 4952 09An American National StandardStandard Test Method forQualitative Analysis for Active Sulfur Species in Fuels andSolvents (Doctor Test)1This standard is issued under the fixed designation D 4952; 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.This standard has been approved for use by agencies of the Department of Defense.1.
3、Scope*1.1 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 uni
4、ts are to 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 prac
5、tices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 3227 Test Method for (Thiol Mercaptan) Sulfur in Gaso-line, Kerosine, Aviation Turbine, and Distillate Fuels(Potentiometric Method)3. Summa
6、ry 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 mercaptans or hydrogen sulfideor both is indicated by discoloration of the sulfur floating at theoil-water interface or by discoloration of
7、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 andnon-metallic materials in fuel and other distribution systems.Anegative result in the doctor test ensures that the concentrationof these com
8、pounds is insufficient to cause such problems innormal use.5. Reagents and Materials5.1 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 America
9、n Chemical Society wheresuch specifications are available.3Other 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.5.2 Purity of WaterUnless otherwise indicated, referencesto water s
10、hall be understood to mean reagent water as definedby Types II or III of Specification D 1193.5.3 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 vigor
11、ously for 15min, or let stand with occasional shakings for at least one day.Allow to settle and decant or siphon off the clear liquid. If thesolution does not settle clear, filter it through filter paper. Keepthe solution in a tightly sealed bottle and refilter before use ifnot perfectly clear. As a
12、n alternative, the lab may use acommercially prepared solution that meets the requirements ofthe laboratory preparation.NOTE 1Alternate volumes of the solution may be prepared orpurchased, provided the final solution concentration is equivalent.5.4 SulfurPure, sublimed, stored in a closed container.
13、6. Procedure6.1 Shake vigorously together 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 of1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the
14、 direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved April 15, 2009. Published May 2009. Originallyapproved in 1989. Last previous edition approved in 2007 as D 495202(2007).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Cu
15、stomer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents n
16、otlisted 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.1*A Summary of Changes section appears at the end of this standar
17、d.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.sulfur so that practically all of it floats on the interface betweenthe sample and the sodium plumbite solution after shaking.Shake again for 15 s. Allow to settle and observe within 2
18、 min.NOTE 2It is important to avoid adding more sulfur than will just coverthe interface. About 20 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 of sulfur.7. Interpretation of Results
19、7.1 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 with gray or flecked with black, report
20、 the test asnegative and consider the sample as sweet.NOTE 3This examination must be made with extreme care. Some-times the sulfur layer will be only flecked with spots of gray or black, andif there is any change in the color of either the sample or the Doctorsolution these spots will be difficult t
21、o 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 sulfur layer after shaking, and small amounts ofmercaptans will only discolor the sulfur. However, samples which containmercaptans will al
22、so 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 required to indicate that a reaction ofmercaptan and sodium plumbite has occurred.NOTE 5When the sample contains appreciable amounts of hydrog
23、ensulfide, 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 stopped at that point and the sample reported as “Does not pass.”However, if this observation is at all doubtful, the test should beconti
24、nued. 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 to drive the sample reaction with sodium plumbite.7.1.1 The relationship between the appearance of thesample and the type of sulfur is
25、shown in Table 1.7.2 If the doctor test is positive, mercaptan content may bedetermined using Test Method D 3227.8. Precision and Bias8.1 No justifiable values of repeatability, reproducibility, orbias for this test method can be stated here because the testdetects only the presence or absence of ac
26、tive sulfur species,such as hydrogen sulfide or mercaptan.9. Keywords9.1 doctor test; hydrogen sulfide; kerosine; mercaptans;motor fuel; sulfurSUMMARY OF CHANGESSubcommittee D02.03 has identified the location of selected changes to this standard since the last issue(D 495202(2007) that may impact th
27、e use of this standard.(1) Updated 6.1, Note 4, Note 5, and Table 1.ASTM 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 determination of the validity of any
28、 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 withdrawn. Your comments are in
29、vited 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 your comments have not receive
30、d 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 (single or multiple copies) of t
31、his 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).TABLE 1 Relationship Between Sample and SulfurAppearance Type of SulfurDarkening of the sample before addition of
32、 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 thesampleHydrogen sulfide absent; mercaptans or elemental sulfur, or both,presentClear yellow Doctor solution; no discoloration of sulfur Hydrogen sulfide and elemental sulfur absent; traces of mercaptanspresentD4952092
