EPA 9076 TEST METHOD FOR TOTAL CHLORINE IN NEW AND USED PETROLEUM

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1、METHOD9076TESTMETHODFORTOTALCHLORINEINNEWANDUSEDPETROLEUMPRODUCTSBYOXIDATIVECOMBUSTIONANDMICROCOULOMETRY1.0SCOPEANDAPPLICATION1.1Thistestmethodcoversthedeterminationoftotalchlorineinnewandusedoils,fuelsandrelatedmaterials,includingcrankcase,hydraulic,diesel,lubricatingandfueloils,andker

2、osenebyoxidativecombustionandmicrocoulometry.Thechlorinecontentofpetroleumproductsisoftenrequiredpriortotheiruseasafuel.1.2Theapplicablerangeofthismethodisfrom10to10,000µg/gchlorine.2.0SUMMARYOFMETHOD2.1Thesampleisplacedinaquartzboatattheinletofahigh-temperaturequartzcombustiontube.Anin

3、ertcarriergassuchasargon,carbondioxide,ornitrogensweepsacrosstheinletwhileoxygenflowsintothecenterofthecombustiontube.Theboatandsampleareadvancedintoavaporizationzoneofapproximately300ECtovolatilizethelightends.Thentheboatisadvancedtothecenterofthecombustiontube,whichisat1,000EC.Theoxyg

4、enisdivertedtopassdirectlyoverthesampletooxidizeanyremainingrefractorymaterial.Allduringthiscompletecombustioncycle,thechlorineisconvertedtochlorideandoxychlorides,whichthenflowintoanattachedtitrationcellwheretheyquantitativelyreactwithsilverions.Thesilverionsthusconsumedarecoulometrica

5、llyreplaced.Thetotalcurrentrequiredtoreplacethesilverionsisameasureofthechlorinepresentintheinjectedsamples.2.2Thereactionoccurringinthetitrationcellaschlorideentersis:-+Cl+Ag------->AgCl(1)Thesilverionconsumedintheabovereactionisgeneratedcoulometricallythus:o+-Ag------->Ag+e(2)2.3These

6、microequivalentsofsilverareequaltothenumberofmicro-equivalentsoftitratablesampleionenteringthetitrationcell.3.0INTERFERENCES3.1Othertitratablehalideswillalsogiveapositiveresponse.ThesetitratablehalidesincludeHBrandHI(HOBr+HOIdonotprecipitatesilver).Becausetheseoxyhalidesdonotreactinthet

7、itrationcell,approximately50%microequivalentresponseisdetectedfrombromineandiodine.3.2Fluorineasfluoridedoesnotprecipitatesilver,soitisnotaninterferantnorisitdetected.CD-ROM9076-1Revision0September19943.3Thistestmethodisapplicableinthepresenceoftotalsulfurconcentrationsofupto10