2024年7月

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4226DeterminationofExtractableTungstenforPrefilledSyringes

Glassprefilledsyringesaretypicallyproducedfromglasstubingviaahot-forming

process.Oneimportantstepofthisprocessistheconeformationandmoreimportantly

itsopeningwithapinthathastheformofafilamentandthatismadeofmaterial

resistanttohightemperaturessuchasatungstenpin.Inthecaseoftungstenpins,

tungstenresidualsmayformontheinnersurfaceoftheglassbarrel.Thismethod

appliestothedeterminationofextractabletungstenofglassprefilledsyringes.

Carryoutthemethodforinductivelycoupledplasmaopticalemission

spectrometry(GeneralChapter0411)orthemethodforinductivelycoupledplasma

massspectrometry(GeneralChapter0412).

Instruments

Inductivelycoupledplasmaopticalemissionspectrometer(ICP-OES),in

accordancewiththerequirementsofinductivelycoupledplasmaopticalemission

spectrometry(GeneralChapter0411).

Inductivelycoupledplasmamassspectrometer(ICP-MS),inaccordancewiththe

requirementsofinductivelycoupledplasmamassspectrometry(GeneralChapter0412).

Ultrasonicbath.

Preparationoftestsolution

Method1

Itisusedtodeterminethewater-solubleamountoftungstenfromglassprefilled

syringes.

Filling:Take1prefilledsyringeandassemblethematchingplungerstopperand

plungerrodasareference.Measureaccuratelytheexactvolume(labelledquantity)of

waterintoasuitablecontainerandaspiratethecompletevolumethroughtheneedleor

theLuerchannelintothesyringewithoutcapturinganyair.Removeaccidentally

capturedairbubblesbyturningthesyringetipupwardsandpushingtheplungerrod

carefully.Closethesyringewithatipcaporaneedleshield,whichisfilledwithwater.

Marktheresultingfillinglevel(positionofthestopper)withapermanentmarker.Then

transferthisfillinglevelfromthereferencesyringetothesyringestobetestedby

suitablemeans,e.g.byaruler,seeFigure1.

Inaddition,take60prefilledsyringes,andassemblethematchingplungerstoppers

andplungerrods.Aspiratethewatertotightlybeneaththemarkwithoutcapturingany

airbubbles.Fillthetipcap/needleshieldwithwaterandclosethesyringewithit.The

excessiveliquidshallberemovedwithapapertowel.

Extraction:Putthesyringesvertically(tipdown)inarackandthenputitintothe

ultrasonicbathpreheatedto75°C±5°C,startthesonicationprocessfor60minutesat

45kHzspecificpowerofatleast16W/l.Whentheextractionisfinished,takeoutthe

rackfromtheultrasonicbath,gentlydryeverysyringeoutsidewithpapertowel.Take

thesyringe,turnittipcapfacingup.Tapthetipcaptomovethebubbletowardsthe

flowchannel,screwtheplungerrodonthestopper,pulltheplungerstoppertoremove

thewaterfromthetipchannelandthentakeoffthetipcap.Flushtheextractionsolution

intothesampletubes.Rinsethesyringestwicebyaspiratingwaterintoeachsyringeto

themarkedpositionandflushitintothesamesampletubewhichcontainstheextraction

solution.Asecondextractionshallbedonewiththesametestsyringesbyreproducing

thesameprocessfrom“aspiratingthepurifiedwatertotightlybeneaththemark”.The

secondextractionsolutionisflushedintothesametubethatcontainsthefirstextraction,

whichwillbethetestsolution.

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Fig.1Transferofthefillinglevelmarkstothesyringestobetested

Method2

Itisusedforthedeterminationoftheextractableamountoftungstenindifferent

formsfromglassprefilledsyringes.

“0.01mol/Lsodiumhydroxidesolution”isusedastheextractionmediumand

rinsingsolution,andtwoextractionsarecarriedoutaccordingtothefirstmethodto

preparethetestsolution.

Preparationofstandardsolutions:Prepareaseriesofcalibrationsolutionsby

dilutionofstandardsolutionwithsuitablemedium,whichincludesaminimumof5

concentrations.

Determination:Theinstrumentshallmeettheusagerequirements,andthe

workingparameterscanbeoptimizedaccordingtothespecificsituation.Determinethe

seriesofcalibrationsolutionsandtestsolution,drawcalibrationcurve,andcalculate

theregressionequationbyusingtheconcentrationofcalibrationsolutionsasthe

abscissaandtherespondcorrespondinglyastheordinate(iftheinternalstandard

methodisusedfordetermination,usingtheratioofthepeakresponsevalueofthe

elementtobemeasuredinthecalibrationsolutiontothatoftheinternalstandard

elementastheordinate).Thelinearcoefficientrisnotlessthan0.99.Calculatethe

concentrationoftungsteninthetestsolutionaccordingtotheregressionequation.

Performablankdeterminationunderthesameanalysisconditionsandmakeany

necessarycorrectionaccordingtotheinstrumentmanual.Ifnecessary,dilutethetest

solutionforanalysis.

Resultrepresentation:Theabsoluteamountofextractabletungstenperprefilled

syringeiscalculatedbasedonthemeasuredconcentrationofextractabletungsten

(ng/ml),andtheresultisexpressedastheabsoluteamountofextractabletungsteninng

perprefilledsyringe.

Note:Itisrecommendedtouserigidplasticcontainers,suchasPTFEcontainers,

duringthe