1、Designation: D 4952 02 (Reapproved 2007)An 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 ye
2、ar oforiginal adoption or, 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.This standard has been approved for use by agencies of the Depart
3、ment of Defense.1. Scope1.1 This test method is intended primarily for the detectionof mercaptans in motor fuel, kerosine, and similar petroleumproducts. This method may also provide information onhydrogen sulfide and elemental sulfur that may be present inthese sample types.1.2 The values stated in
4、 acceptable SI units are to beregarded as standard.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 determine the applica-bility of
5、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. Summary of Test Method3.1 The sample is shaken
6、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 either of the phases.4. Significance and U
7、se4.1 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 compounds is insufficient to cause such probl
8、ems 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 American Chemical Society wheresuch specification
9、s 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 shall be understood to mean reagent water a
10、s 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 vigorously for 15min, or let stand with occasio
11、nal 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 an alternative, the lab may use acommercial
12、ly 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.6. Procedure6.1 Shake vigorously together
13、in a test tube 10 mL of thesample being tested and 5 mL of sodium plumbite solution for1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved May 1, 20
14、07. Published June 2007. Originallyapproved in 1989. Last previous edition approved in 2002 as D 4952 02.2For 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 standar
15、ds Document Summary page onthe ASTM website.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Do
16、rset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.about 15 s. Add a small amount of pure, sublimed sulfur of
17、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 min.NOTE 2It is important to avoid adding more sulfur than will just coverthe interface. About 20 to 25 mg is the p
18、roper 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 Results7.1 If the solution is discolored or if the yellow color of thesulfur film is noticeably masked, report the test as
19、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 the test asnegative and consider the sample as sweet.NOTE 3This examination must be made with extreme care. Some-ti
20、mes 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 to detect.NOTE 4Strictly speaking, the test will not reject the sample on thebasis of mercaptans only. The primary cr
21、iterion for rejection is theappearance of the sulfur 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.NOTE 5When
22、 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 stopped at that point and the sample reported as “Does not pass.”However, if this obser
23、vation is at all doubtful, the test should becontinued.7.1.1 The relationship between the appearance of thesample and the type of sulfur is 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
24、of repeatability, reproducibility, orbias 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.9. Keywords9.1 doctor test; hydrogen sulfide; kerosine; mercaptans;motor fuel; sulfurASTM Internationa
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26、wn 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 invited either for revision of this standard or for additional standardsand should be a
27、ddressed 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 received a fair hearing you shouldmake your views known to the ASTM Committee on Standards,
28、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 this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-958
29、5 (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 SulfurBlack precipitate before addition of sulfur Appreciable amounts of hydrogen sulfideBlack color of sulfur after shaking Traces o
30、f 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 mercaptanspresentD 4952 02 (2007)2
