usp921水分测定法中文翻译下

1、Methodlb（ResidualTitration）方式lb（残留滴定）PrincipleSeetheinformationgiveninthesectionPrincipleunderMethodIa.Intheresidualtitration,excessReagentisaddedtothetestspecimen,sufficienttimeisallowedforthereactiontoreachcompletion,andtheunconsumedReagentistitratedwithastandardsolutionofwaterinasolventsuchasmeth

2、anol.Theresidualtitrationprocedureisapplicablegenerallyandavoidsthedifficultiesthatmaybeencounteredinthedirecttitrationofsubstancesfromwhichtheboundwaterisreleasedslowly.原理：见方式la项下原理部份给出的信息。在残留滴定中，额外的试剂被加入到供试样品中，为反映的完成留下了充分的时刻，而且将未消耗掉的试剂与水和某种溶剂（例如，甲醇）的标准溶液一路滴定。残留滴定程序一般是可行的，并幸免了可能在直接滴定该物质进程中碰到的困难，这些物

3、质中被束缚水分释放得很缓慢。Apparatus,Reagent,andTestPreparationUseMethodIa.仪器、试剂、供试配制液：同方式la。StandardizationofWaterSolutionforResidualTitrationPrepareaWaterSolutionbydiluting2mLofwaterwithmethanolorothersuitablesolventto1000mL.Standardizethissolutionbytitrating25.0mLwiththeReagent,previouslystandardizedasdirecte

4、dunderStandardizationoftheReagent.Calculatethewatercontent,inmgpermL,oftheWaterSolutiontakenbytheformula:用于残留滴定的水溶液的标准化：以甲醇或其他适当溶剂将2mL水稀释至lOOOmL，以配制水溶液。利用此前已经按照试剂的标准化项下规定进行过标准化的试剂，对25mL此溶液进行滴定，从而对其进行标准化。依照下面的公式，计算此水溶液中的水分含量（单位mg/mL）：VF/25,inwhichVisthevolumeoftheReagentconsumed,andFisthewaterequival

5、encefactoroftheReagent.DeterminethewatercontentoftheWaterSolutionweekly,andstandardizetheReagentagainstitperiodicallyasneeded.其中，V是消耗掉的试剂，F是试剂的水平稳因子。每周测定水溶液的水分含量，并据此依照需要按期对试剂进行标准化。Procedure一WheretheindividualmonographspecifiesthatthewatercontentistobedeterminedbyMethodIb,transfer35to40mLofmethanolor

6、othersuitablesolventtothetitrationvessel,andtitratewiththeReagenttotheelectrometrieorvisualendpoint.QuicklyaddtheTestPreparation,mix,andaddanaccuratelymeasuredexcessofthcReagent.Allowsufficienttimeforthereactiontoreachcompletion,andtitratetheunconsumedReagentwithstandardizedWaterSolutiontotheelectro

7、metrieorvisualendpoint.Calculatethewatercontentofthespecimen,inmg,takenbytheformula:步骤：当具体各论中规定用方式lb测定水分含量时，将35至40mL甲醇或其他适当溶剂转移至该滴定容器，并用试剂滴定至测电法或视觉观看的终点。快速加入供试配制品，混匀，并加入精准称量的额外试剂。留下充分的时刻以使该反映完成，利用标准化的水溶液对未消耗的试剂进行滴定至测电法或视觉观看的终点。依照下面的公式，计算样品中的水分含量(单位mg)：F(X-XR),inwhichFisthewaterequivalencefactorofthe

8、Reagent;Xisthevolume,inmL,oftheReagentaddedafterintroductionofthespecimenXisthevolume,inmL,ofstandardizedWaterSolutionrequiredtoneutralizetheunconsumedReagent;andRistheratio,V/25(mLReagent/mLWaterSolutior),determinedfromtheStandardizationofWaterSolutionforResidualTitration.其中，F是试剂的水平稳因子；X是在放入样品后加入的试

9、剂体积（单位mL）；X是用于中和未消耗试剂所必需的已标准化水溶液的体积（单位mL）；R是通过用于残留滴定的水溶液的标准化来则定的,V/25的比值（mL试剂/mL水溶液）。MethodIc(CoulometrieTitration)方式Ic(库仑滴定)Principle一TheKarlFischerreaetionisusedinthecoulometriedeterminationofwater.Iodine,however,isnotaddedintheformofavolumetriesolutionbutisproducedinaniodide-containingsolutionbya

10、nodicoxidation.Thereactioncellusuallyconsistsofalargeanodecompartmentandasmallcathodecompartmentthatareseparatedbyadiaphragm.Othersuitabletypesofreactioncells(e.g.,withoutdiaphragms)mayalsobeused.Eachcompartmenthasaplatinumelectrodethatconductscurrentthroughthecell.Iodine,whichisproducedattheanodeel

11、ectrode,immediatelyreactswithwaterpresentinthecompartment.Whenallthewaterhasbeenconsumed,anexcessofiodineoccurs,whichusuallyisdetectedelectrometrically,thusindicatingtheendpoint.Moistureiseliminatedfromthesystembypre-electrolysis.ChangingtheKarlFischersolutionaftereachdeterminationisnotnecessarysinc

12、eindividualdeterminationscanbecarriedoutinsuccessioninthesamereagentsolution.Arequirementforthismethodisthateachcomponentofthetestspecimeniscompatiblewiththeothercomponents,andnosidereactionstakeplace.Samplesareusuallytransferredintothevesselassolutionsbymeansofinjectionthroughaseptum.Gasescanbeintr

13、oducedintothecellbymeansofasuitablegasinlettube.Precisioninthemethodispredominantlygovernedbytheextenttowhichatmosphericmoistureisexcludedfromthesystem;thus,theintroductionofsolidsintothecellisnotrecommended,unlesselaborateprecautionsaretaken,suchasworkinginaglove-boxinanatmosphereofdryinertgas.Cont

14、rolofthesystemmaybemonitoredbymeasuringtheamountofbaselinedrift.Thismethodisparticularlysuitedtochemicallyinertsubstanceslikehydrocarbons,alcohols,andethers.IncomparisonwiththevolumetricKarlFischertitration,coulometryisamicro-method.原理：库仑滴定法水分测定应用了卡尔费休反映的原理。可是，碘不是加入到滴定液中，而是通过阳极氧化在含碘溶液中产生。该反映单元通常由一大、

15、一小两个阳极室组成，二者中间以隔膜分开。也能够利用其他适合的反映单元（例如，没有隔膜）类型。每一个阳极室有一个白金电极，会穿过该单元导电。在阳极生成的碘立刻与该阳极室内存在的水发生反映。当所有的水都被消耗以后，多余的碘显现了，这一样通过电势滴定来检测，从而显示终点水分被预电解从该系统中排除。没有必要在每次检测后改换卡尔费休溶液，因为能够在同一个试剂溶液中持续进行假设干单个测定。此方式的一项要求是该供试品的每一个阳极室均与其他阳极室兼容，而且不发生副反映。样品通常以溶液形态，穿过隔膜注射至该容器中。其他能够利用适当的气体注入管来引入到该单元。该方式的周密程度要紧取决于将大气中水分阻碍从该系统中排

16、除的程度；因此，除非采取了精心设计的预防方法，例如利用手套箱在有干燥入口气体的环境中工作，不然不建议向该单元中加入固体。能够通过测量基线漂移数量，来监测该系统的操纵。此方式专门适合于化学性质迟缓的的物质，例如碳氢化合物、醇类、醚类。与定量测定的卡尔费休滴定法相较，库仑法是一个小方式。ApparatusAnycommerciallyavailableapparatusconsistingofanabsolutelytightsystemfittedwiththenecessaryelectrodesandamagneticstirrerisappropriate.Theinstrumentsmi

17、croprocessorcontrolstheanalyticalprocedureanddisplaystheresults.Calibrationoftheinstrumentisnotnecessary,asthecurrentconsumedcanbemeasuredabsolutely.仪器：任何市场上销售的仪器，其中包括一个绝对密闭的系统，并装备了必需的电极和磁性搅拌器。该仪器的微处置器操纵着分析程序并显示结果。该仪器没必要校准，因为消耗的电流绝对能够被测量到。ReagentSeeReagentunderMethodIa.试剂：见方式la项下试剂。TestPreparationWh

18、erethespecimenisasolublesolid,dissolveanappropriatequantity,accuratelyweighed,inanhydrousmethanolorothersuitablesolvents.Liquidsmaybeusedassuchorasaccuratelypreparedsolutionsinappropriateanhydroussolvents.供试配制品：若是样品为可溶性固体，周密称定假设干该样品，溶于无水甲醇或其他适合的溶剂中。这些液体能够如此利用，或利用在适当的无水溶剂中周密配制溶液。Wherethespecimenisani

19、nsolublesolid,thewatermaybeextractedusingasuitableanhydroussolventfromwhichanappropriatequantity,accuratelyweighed,maybeinjectedintotheanolytesolution.Alternativelyanevaporationtechniquemaybeusedinwhichwaterisreleasedandevaporatedbyheatingthespecimeninatubeinastreamofdryinertgas,thisgasbeingthenpass

20、edintothecell.若是该样品为不溶性样品，其中的水分能够利用适当的无水溶剂提掏出来，将一部份周密称定的溶剂注入阳极电解溶液。或，能够利用蒸发的方式，通过加热该样品将其中的水分释放和蒸发处处于干燥入口气流里的管子中，然后这些气体被传送到该单元中。ProcedureUsingadrysyringe,quicklyinjecttheTestPreparation,accuratelymeasuredandestimatedtocontain0.5to5mgofwater,orasrecommendedbytheinstrumentmanufacturerintotheanolyte,mix

21、,andperformthecoulometrictitrationtotheelectrometricendpoint.ReadthewatercontentoftheTestPreparationdirectlyfromtheinstrumentsdisplay,andcalculatethepercentagethatispresentinthesubstance.Performablankdetermination,andmakeanynecessarycorrections.步骤：利用干燥注射器，将供试配制液，其通过精准称量并估量含有约一5mg水，或依照仪器生产商的建议，快速注射入阳

22、极电解液，混匀，并对电势终点作库仑滴定法。直接从仪器显示中读取该供试配制液的水分含量，并计算该物质中存在水分的百分比。进行空白检测，并作任何适当的校正。METHODII(AZEOTROPICTOLUENEDISTILLATION)ApparatusUsea500-mLglassflaskAconnectedbymeansofatrapBtoarefluxcondenserCbygroundglassjoints(seeFigure).TolueneMoistureApparatusThecriticaldimensionsofthepartsoftheapparatusareasfollows

23、.TheconnectingtubeDis9to11mmininternaldiameter.Thetrapis235to240mminlength.Thecondenser,ifofthestraight-tubetype,isapproximately400mminlengthandnotlessthan8mminborediameter.ThereceivingtubeEhasa5-mLcapacity,anditscylindricalportion,146to156mminlength,isgraduatedin0.1-mLsubdivisions,sothattheerrorofr

24、eadingisnotgreaterthan0.05mLforanyindicatedvolume.Thesourceofheatispreferablyanelectricheaterwithrheostatcontroloranoilbath.Theupperportionoftheflaskandtheconnectingtubemaybeinsulated.Cleanthereceivingtubeandthecondenserwithchromicacidcleansingmixture,thoroughlyrinsewithwater,anddryinanoven.Preparet

25、hetoluenetobeusedbyfirstshakingwithasmallquantityofwater,separatingtheexcesswater,anddistillingthetoluene.ProcedurePlaceinthedryflaskaquantityofthesubstance,weighedaccuratelytothenearestcentigram,whichisexpectedtoyield2to4mLofwater.Ifthesubstanceisofapastycharacter,weighitinaboatofmetalfoilofasizeth

26、atwilljustpassthroughtheneckoftheflask.Ifthesubstanceislikelytocausebumping,addenoughdry,washedsandtocoverthebottomoftheflask,oranumberofcapillarymelting-pointtubes,about100mminlength,sealedattheupperend.Placeabout200mLoftolueneintheflask,connecttheapparatus,andfillthereceivingtubeEwithtoluenepoured

27、throughthetopofthecondenser.Heattheflaskgentlyfor15minutesand,whenthetoluenebeginstoboil,distillattherateofabout2dropsperseconduntilmostofthewaterhaspassedover,thenincreasetherateofdistillationtoabout4dropspersecond.Whenthewaterhasapparentlyalldistilledover,rinsetheinsideofthecondensertubewithtoluenewhilebrushingdownthetubewithatubebrushattachedtoacopperwireandsaturatedwithtoluene.Continuethedistillationfor5minutes,thenremovetheheat,andallowthereceivingtubetocooltoroomtemperature.Ifanydropletsofwateradheretothewallsofthereceivingtube,scrubthe