ASTM_D_4952_-_12.pdf

Designation:D495212Standard 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 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.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 units 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 practices and determine the applica-bility of regulatory limitations prior to use.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 Method)2.2 Energy Institute Standards:3IP30 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 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 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 problems innormal use.5.Interferences5.1 This test cannot be used if there are more than traceamounts of peroxides in the 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 6 0.5 mL of a freshportion of the sample with approximately 2 mL of thepotassium iodide solution,add two drops of the acetic acidsolution,and two drops of the starch solution.If the aqueouslayer turns a blue color,this confirms the presence of peroxidesin sufficient quantity to invalidate the test,and the test on thissample should be discontinued.Proceed in accordance with5.4.5.3 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,proceed tore-sample and retest.Ensure that sampling and handlingprocedures for the new sample prevent UV light exposures asprescribed in 7.1.None of the normal refinery units or blendingprocesses producing spark ignition motor fuels are known tocreate peroxides under normal operating conditions.1This 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 April 15,2012.Published June 2012.Originallyapproved in 1989.Last previous edition approved in 2009 as D495209.DOI:10.1520/D4952-12.2For 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.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 andEngineering Chemistry,Vol 16,No.6,June 1924,p.588.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 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 Chemical 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