ASTM_D_7184_-_15.pdf

Designation:D718415Standard Test Method forUltra Low Nitrogen in Aromatic Hydrocarbons by OxidativeCombustion and Reduced Pressure ChemiluminescenceDetection1This standard is issued under the fixed designation D7184;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.Scope*1.1 This test method covers the determination of totalnitrogen in aromatic hydrocarbons,such as benzene,toluene,and xylene.1.2 This test method is applicable for samples containingnitrogen from 0.1 to 1.2 mg N/kg.For higher nitrogenconcentrations refer to Test Method D4629.With carefulanalytical technique,this method can be used to successfullyanalyze concentrations below the current scope(see AppendixX1).1.3 In determining the conformance of the test results usingthis method to applicable specifications;results shall berounded off in accordance with the rounding-off method ofPractice E29.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 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.For specific hazardstatements,see Section 9.2.Referenced Documents2.1 ASTM Standards:2D3437 Practice for Sampling and Handling Liquid CyclicProductsD4629 Test Method for Trace Nitrogen in Liquid PetroleumHydrocarbons by Syringe/Inlet Oxidative Combustion andChemiluminescence DetectionD6809 Guide for Quality Control and Quality AssuranceProcedures for Aromatic Hydrocarbons and Related Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 Other Documents:OSHA Regulations,29 CFR paragraphs 1910.1000 and1910.120033.Terminology3.1 Definitions:3.1.1 oxidative pyrolysis,na process in which a sampleundergoes combustion in an oxygen rich environment attemperatures greater than 900C.3.1.2 pyrolytic decomposition,ncombusting a compoundto decompose it to carbon dioxide,water and elemental oxides.3.1.3 reduced pressure chemiluminescence,na chemicalreaction at pressure less than 760 mm mercury(Hg)in whichlight is emitted.4.Summary of Test Method4.1 A specimen is introduced into a carrier gas stream,at acontrolled rate,and incorporated into a high temperaturefurnace(900 to 1150C)where an excess of oxygen is added.Pyrolysis converts hydrocarbons in the specimen to carbondioxide and water.Organic nitrogen and inorganic nitrogencompounds,present in the specimen,are converted to nitricoxide(NO).Nitric oxide reacts with ozone in the detectorproducing nitrogen dioxide molecules in an excited state.Asthe excited nitrogen dioxide molecules relax to ground state,light is emitted.This light is detected by a photomultiplier tubeor by a photodiode with the resulting signal proportional to theconcentration of nitrogen in the sample.Operating the detectorat a reduced pressure lowers the probability of the excited1This test method is under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and is the direct responsibility ofSubcommittee D16.04 on Instrumental Analysis.Current edition approved June 1,2015.Published June 2015.Originallyapproved in 2007.Last previous edition approved in 2013 as D7184 13.DOI:10.1520/D7184-15.2For 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 U.S.Government Printing Office Superintendent of Documents,732 N.Capitol St.,NW,Mail Stop:SDE,Washington,DC 20401,http:/www.access.gpo.gov.*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 nitrogen dioxide molecule colliding with other moleculesbefore it undergoes chemiluminescence.Thus,reduced pres-sure provides improved sensitivity and lower noise.5.Significance and Use5.1 This test method is useful to detect and quantifynitrogen-containing compounds at a concentration of 0.1 to 1.2mg N/kg in light aromatic hydrocarbons used or produced inmanufacturing process.These nitrogen-containing compoundsare undesirable in finished aromatic products and may be usedin setting specification for determining the total nitrogencontent in aromatic hydrocarbons.5.2 This test method requires the use of reduced pressure atthe detector.Loss of vacuum or pressure fluctuations impactthe sensitivity