ASTM_D_4768_-_11.pdf

Designation:D476811Standard Test Method forAnalysis of 2,6-Ditertiary-Butyl Para-Cresol and 2,6-Ditertiary-Butyl Phenol in Insulating Liquids by GasChromatography1This standard is issued under the fixed designation D4768;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.1.Scope1.1 This test method covers the determination by gaschromatography of 2,6-ditertiary-butyl para-cresol and 2,6-ditertiary-butyl phenol in new and used insulating liquids atconcentrations up to 0.5%.It includes the determination inType I and II insulating mineral oils as specified in Specifica-tion D3487,but has also been used to measure these inhibitorsin other insulating liquids,such as esters and high fire-pointhydrocarbons.1.2 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:2D923 Practices for Sampling Electrical Insulating LiquidsD3487 Specification for Mineral Insulating Oil Used inElectrical ApparatusD5222 Specification for High Fire-Point Mineral ElectricalInsulating OilsE260 Practice for Packed Column Gas Chromatography3.Summary of Test Method3.1 The test specimen is placed onto a column containingactivated alumina and extracted to remove interfering sub-stances.The inhibitors are then eluted from the column withsuitable solvent and analyzed by gas chromatography.Theinhibitor type and quantity are determined by comparison ofeach component with a working standard tested under similarconditions.4.Significance and Use4.1 In new electrical insulating oil,this test method providesa quantitative measure of the amounts of 2,6-ditertiary-butylpara-cresol and 2,6-ditertiary-butyl phenol that have beenadded to the oil.In a used oil,the test measures the amount ofthese inhibitors remaining in the oil.This test method issuitable for manufacturing control,specification acceptance,and service evaluation.4.2 This test method is used to separate,identify,andquantify the inhibitors with minimal interference and matrixeffects.4.3 This test method has also been used successfully todetermine the inhibitor concentrations in other insulatingliquids such as esters and high-temperature hydrocarbons.5.Apparatus5.1 Gas Chromatograph,equipped with oven temperaturecontrol constant to 1C and with heated injector port.5.1.1 Means to Record the Chromatogram,such as a penrecorder or a digital integrator to determine peak areas,isrecommended.An automated sample injector may be used.5.2 Flame Ionization Detector,with appropriate hydrogen/air gas flows,is preferred over a thermal conductivity detectorto provide maximum sensitivity.5.3 Column,a suitable stainless steel or glass columnpacked with a nonpolar silicone on an appropriate support orequivalent capillary column.NOTE1A 3%OV-13on 100/120 Mesh Supelcoport,41.83 m(6 ft)long,3.2 mm(0.125 in.)in outside diameter has been used successfully.A SPB-1430 m by 0.53 mm 1m film column has also been usedsuccessfully.5.3.1 Condition columns in accordance with manufacturersrecommendations.Disconnect columns from detector prior toconditioning and reconnect after conditioning.5.4 Precision Syringe,glass,10.0 L.1This test method is 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 Aug.1,2011.Published September 2011.Originallyapproved in 1988 as D4768 88.Last previous edition approved in 2003 asD4768 03.DOI:10.1520/D4768-11.2For 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.3Registered trademark of Ohio Valley Specialty Co.4Registered trademark of Supelco,Inc.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.5 Volumetric Glassware,appropriate for making dilutions.5.6 Pipets,Pasteur,disposable,146 by 7.5 mm.5.7 Analytical Balance.5.8 Automatic Pipetter,1 mL calibrated,adjustable.5.9 Oven,capable of maintaining a temperature of 325 65C for conditioning extraction columns.5.10 Desiccator.6.Reagents and Materials6.1 Purity of ReagentsUse reagent grade chemicals in alltests.Unless otherwise indicated,it is intended that all reagentsshall 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 reag