usp921水分測(cè)定法中文翻譯下

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

2、anol.Theresidualtitrationprocedureisapplicablegenerallyandavoidsthedifficultiesthatmaybeencounteredinthedirecttitrationofsubstancesfromwhichtheboundwaterisreleasedslowly.原理：見(jiàn)方式la項(xiàng)下原理部份給出的信息。在殘留滴定中，額外的試劑被加入到供試樣品中，為反映的完成留下了充分的時(shí)刻，而且將未消耗掉的試劑與水和某種溶劑（例如，甲醇）的標(biāo)準(zhǔn)溶液一路滴定。殘留滴定程序一般是可行的，并幸免了可能在直接滴定該物質(zhì)進(jìn)程中碰到的困難，這些物

3、質(zhì)中被束縛水分釋放得很緩慢。Apparatus,Reagent,andTestPreparationUseMethodIa.儀器、試劑、供試配制液：同方式la。StandardizationofWaterSolutionforResidualTitrationPrepareaWaterSolutionbydiluting2mLofwaterwithmethanolorothersuitablesolventto1000mL.Standardizethissolutionbytitrating25.0mLwiththeReagent,previouslystandardizedasdirecte

4、dunderStandardizationoftheReagent.Calculatethewatercontent,inmgpermL,oftheWaterSolutiontakenbytheformula:用于殘留滴定的水溶液的標(biāo)準(zhǔn)化：以甲醇或其他適當(dāng)溶劑將2mL水稀釋至lOOOmL，以配制水溶液。利用此前已經(jīng)按照試劑的標(biāo)準(zhǔn)化項(xiàng)下規(guī)定進(jìn)行過(guò)標(biāo)準(zhǔn)化的試劑，對(duì)25mL此溶液進(jìn)行滴定，從而對(duì)其進(jìn)行標(biāo)準(zhǔn)化。依照下面的公式，計(jì)算此水溶液中的水分含量（單位mg/mL）：VF/25,inwhichVisthevolumeoftheReagentconsumed,andFisthewaterequival

5、encefactoroftheReagent.DeterminethewatercontentoftheWaterSolutionweekly,andstandardizetheReagentagainstitperiodicallyasneeded.其中，V是消耗掉的試劑，F(xiàn)是試劑的水平穩(wěn)因子。每周測(cè)定水溶液的水分含量，并據(jù)此依照需要按期對(duì)試劑進(jìn)行標(biāo)準(zhǔn)化。Procedure一WheretheindividualmonographspecifiesthatthewatercontentistobedeterminedbyMethodIb,transfer35to40mLofmethanolor

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

7、metrieorvisualendpoint.Calculatethewatercontentofthespecimen,inmg,takenbytheformula:步驟：當(dāng)具體各論中規(guī)定用方式lb測(cè)定水分含量時(shí)，將35至40mL甲醇或其他適當(dāng)溶劑轉(zhuǎn)移至該滴定容器，并用試劑滴定至測(cè)電法或視覺(jué)觀看的終點(diǎn)?？焖偌尤牍┰嚺渲破罚靹?，并加入精準(zhǔn)稱(chēng)量的額外試劑。留下充分的時(shí)刻以使該反映完成，利用標(biāo)準(zhǔn)化的水溶液對(duì)未消耗的試劑進(jìn)行滴定至測(cè)電法或視覺(jué)觀看的終點(diǎn)。依照下面的公式，計(jì)算樣品中的水分含量(單位mg)：F(X-XR),inwhichFisthewaterequivalencefactorofthe

8、Reagent;Xisthevolume,inmL,oftheReagentaddedafterintroductionofthespecimenXisthevolume,inmL,ofstandardizedWaterSolutionrequiredtoneutralizetheunconsumedReagent;andRistheratio,V/25(mLReagent/mLWaterSolutior),determinedfromtheStandardizationofWaterSolutionforResidualTitration.其中，F(xiàn)是試劑的水平穩(wěn)因子；X是在放入樣品后加入的試

9、劑體積（單位mL）；X是用于中和未消耗試劑所必需的已標(biāo)準(zhǔn)化水溶液的體積（單位mL）；R是通過(guò)用于殘留滴定的水溶液的標(biāo)準(zhǔn)化來(lái)則定的,V/25的比值（mL試劑/mL水溶液）。MethodIc(CoulometrieTitration)方式Ic(庫(kù)侖滴定)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：庫(kù)侖滴定法水分測(cè)定應(yīng)用了卡爾費(fèi)休反映的原理?？墒?，碘不是加入到滴定液中，而是通過(guò)陽(yáng)極氧化在含碘溶液中產(chǎn)生。該反映單元通常由一大、

15、一小兩個(gè)陽(yáng)極室組成，二者中間以隔膜分開(kāi)。也能夠利用其他適合的反映單元（例如，沒(méi)有隔膜）類(lèi)型。每一個(gè)陽(yáng)極室有一個(gè)白金電極，會(huì)穿過(guò)該單元導(dǎo)電。在陽(yáng)極生成的碘立刻與該陽(yáng)極室內(nèi)存在的水發(fā)生反映。當(dāng)所有的水都被消耗以后，多余的碘顯現(xiàn)了，這一樣通過(guò)電勢(shì)滴定來(lái)檢測(cè)，從而顯示終點(diǎn)水分被預(yù)電解從該系統(tǒng)中排除。沒(méi)有必要在每次檢測(cè)后改換卡爾費(fèi)休溶液，因?yàn)槟軌蛟谕粋€(gè)試劑溶液中持續(xù)進(jìn)行假設(shè)干單個(gè)測(cè)定。此方式的一項(xiàng)要求是該供試品的每一個(gè)陽(yáng)極室均與其他陽(yáng)極室兼容，而且不發(fā)生副反映。樣品通常以溶液形態(tài)，穿過(guò)隔膜注射至該容器中。其他能夠利用適當(dāng)?shù)臍怏w注入管來(lái)引入到該單元。該方式的周密程度要緊取決于將大氣中水分阻礙從該系統(tǒng)中排

16、除的程度；因此，除非采取了精心設(shè)計(jì)的預(yù)防方法，例如利用手套箱在有干燥入口氣體的環(huán)境中工作，不然不建議向該單元中加入固體。能夠通過(guò)測(cè)量基線漂移數(shù)量，來(lái)監(jiān)測(cè)該系統(tǒng)的操縱。此方式專(zhuān)門(mén)適合于化學(xué)性質(zhì)遲緩的的物質(zhì)，例如碳?xì)浠衔?、醇?lèi)、醚類(lèi)。與定量測(cè)定的卡爾費(fèi)休滴定法相較，庫(kù)侖法是一個(gè)小方式。ApparatusAnycommerciallyavailableapparatusconsistingofanabsolutelytightsystemfittedwiththenecessaryelectrodesandamagneticstirrerisappropriate.Theinstrumentsmi

17、croprocessorcontrolstheanalyticalprocedureanddisplaystheresults.Calibrationoftheinstrumentisnotnecessary,asthecurrentconsumedcanbemeasuredabsolutely.儀器：任何市場(chǎng)上銷(xiāo)售的儀器，其中包括一個(gè)絕對(duì)密閉的系統(tǒng)，并裝備了必需的電極和磁性攪拌器。該儀器的微處置器操縱著分析程序并顯示結(jié)果。該儀器沒(méi)必要校準(zhǔn)，因?yàn)橄牡碾娏鹘^對(duì)能夠被測(cè)量到。ReagentSeeReagentunderMethodIa.試劑：見(jiàn)方式la項(xiàng)下試劑。TestPreparationWh

18、erethespecimenisasolublesolid,dissolveanappropriatequantity,accuratelyweighed,inanhydrousmethanolorothersuitablesolvents.Liquidsmaybeusedassuchorasaccuratelypreparedsolutionsinappropriateanhydroussolvents.供試配制品：若是樣品為可溶性固體，周密稱(chēng)定假設(shè)干該樣品，溶于無(wú)水甲醇或其他適合的溶劑中。這些液體能夠如此利用，或利用在適當(dāng)?shù)臒o(wú)水溶劑中周密配制溶液。Wherethespecimenisani

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

20、edintothecell.若是該樣品為不溶性樣品，其中的水分能夠利用適當(dāng)?shù)臒o(wú)水溶劑提掏出來(lái)，將一部份周密稱(chēng)定的溶劑注入陽(yáng)極電解溶液?；颍軌蚶谜舭l(fā)的方式，通過(guò)加熱該樣品將其中的水分釋放和蒸發(fā)處處于干燥入口氣流里的管子中，然后這些氣體被傳送到該單元中。ProcedureUsingadrysyringe,quicklyinjecttheTestPreparation,accuratelymeasuredandestimatedtocontain0.5to5mgofwater,orasrecommendedbytheinstrumentmanufacturerintotheanolyte,mix

21、,andperformthecoulometrictitrationtotheelectrometricendpoint.ReadthewatercontentoftheTestPreparationdirectlyfromtheinstrumentsdisplay,andcalculatethepercentagethatispresentinthesubstance.Performablankdetermination,andmakeanynecessarycorrections.步驟：利用干燥注射器，將供試配制液，其通過(guò)精準(zhǔn)稱(chēng)量并估量含有約一5mg水，或依照儀器生產(chǎn)商的建議，快速注射入陽(yáng)

22、極電解液，混勻，并對(duì)電勢(shì)終點(diǎn)作庫(kù)侖滴定法。直接從儀器顯示中讀取該供試配制液的水分含量，并計(jì)算該物質(zhì)中存在水分的百分比。進(jìn)行空白檢測(cè)，并作任何適當(dāng)?shù)男ＵETHODII(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