(5.8)-4.8标准加入法测定水中铜

4.8StandardadditionmethodforthedeterminationoftracecopperinwaterAtomicabsorptionspectrometrymoduleofTheabsorbanceofeachtestsolutionismeasuredunderthesamemeasurementconditions,andtheworkingcurveisplottedandextrapolatedtotheconcentrationaxis,andtheinterceptontheconcentrationaxisistheunknownconcentrationcX.StandardadditionofquorumStandardadditionmethodworkingcurveIncrementC

InstrumentAtomicabsorptionspectrophotometer.Aircompressors.Acetylenecylinders.Copperhollowcathodelamps.Glassmeasuringinstrumentsandcontainers:four50mLvolumetricflasks;one5and10mLpipetteeach;one100mLbeaker.InstrumentReagentCopperstandardstocksolutionρ(cu)=1.000mg/mL:weigh1.0000gofcoppermetal,putitina100mLbeaker,addHNO3(1+1)20mL,heatanddissolve.Steamuntilnearlydry,coolandaddHNO3(1+1)5mL,adddistilledwaterandboiltodissolvethecoppersalt,coolandtransfertoa1000mLvolumetricflask,fixthevolumeandshakewell.Copperstandardworkingsolutionρ(cu)=0.1000mg/mL:aspirate25.00mLoftheabovecopperstandardstocksolution,with2+100nitricacidvolumeto250mL.Containcopperwatersamples.标准贮备液ρCu=1.000mgmL-1

StandardcopperstockReagentStartupoperation1.Turnonthepowersupply,startthecomputer2.Installthecopperhollowcathodelamp,andturnonthemainengine;3.Opentheoperationsoftwareforinitialization;4.Burnertolight;

SetthefollowingexperimentalconditionsAnalysisline:324.8nmspectral;bandwidth:0.4nm;hollowcathodelampcurrent:3mAAcetyleneflowrate:2000mL/min;burnerheight:6mmSettingexperimentalconditionsPreheatinginstrumentsAftertheinstrumentconditionsaresetup,enterthemeasuringinterfaceandpreheattheinstrument.StandardseriessolutionrequirementsInordertoensuretheaccuracyofthemeasurement,thestandardmethodrequiresthefollowingquantification：Thecorrespondingstandardcurveshouldbeastraightlinethroughtheorigin,andtheconcentrationofthecomponenttobemeasuredshouldbewithinthislinearrange.Theconcentrationofthestandardsolutionaddedinthesecondpartshouldbeclosetothatofthesample,sothattheslopeofthecurvewillbetoolargeortoosmall,whichwillmaketheerrorofdeterminationgreater.Inordertoobtainmoreaccurateextrapolationresults,atleastfourpointsshouldbeusedtomakeextrapolationcurves.Forthisexperiment,canyoudesignasolutionpreparationschemetocompletethedeterminationofcopperinthetestsolution?Itisknownthattheconcentrationofthesamplesis2-3µg/mL,andthelinearrangeofcopperis0-5µg/mLStudentscanaddaseriesofsolutionsaccordingtothepreparationcriteriashowninthetablebelow.Volumebottlenumber1234VolumeofsampleaddedV1/mL25.0025.0025.0025.00Volumeofρ=100µg/mLcopperstandardsolutionadded/mL0.000.501.001.50Constantvolume/mL50.0050.0050.0050.00Note:Use(2+100)dilutenitricacidforvolumefixing.Solutionformulation(referencescheme)SampleparametersettingCalibrationmethodinput:standardadditionConcentrationunit:µgmL-1Standardsamplename:copperstandardsampleNumberofinputstandardsamples:1,2,3,4Inputstandardadditionconcentration:0.00,1.00,2.00,3.00IgnitionOpenaircompressor,adjustoutletpressureis0.3MPaOpenacetylenecylindertoadjusttheoutletpressureof0.05MPaOpentheexhaustair;Checkdrainagesafetyinterlockdevices;LightaflameMeasurementoperationsAftertheconditionisset,click"measure";Inhalingablanksolutionto"zero"it;Theabsorbancewasdeterminedbyinhalationofstandardseriessolution.Themeasurementiscompletedandthestandardcurveisdisplayed.Displaysampleconcentration;Savethemeasureddata.RecordexperimentaldataVolumetricbottlenumber1234AddsamplevolumeV1/mL25.0025.0025.0025.00ρ＝100

µg/mLcopperstandardsolution/mL0.000.501.001.50Constantvolume/mL50．0050．0050．0050．00IncreaseofcopperconcentrationC(Cu)/µgmL-10．001．002．003．00AbsorbanceAAxA1..

A2A3Convertthevolumeofcopperstandardsolutionintotheconcentrationincrementofthesolutionandfillinthefollowingtable.ShutdownAfterthedetermination,suckandspraythedistilledwaterfor5minutestocleantheburner.ClosingacetylenecylinderShutdownaircompressorafterflameisextinguishedCloseacetylenecylinderQuitworkingsoftwareTurnoffthemainframepowerTurnoffthecomputerFillintheusingrecordofinstrumentThestandardisdrawnandaddedtotheworkingcurve,whichisextendedandintersectedwiththeconcentrationaxis,andtheconcentrationoftheintersectionpointisrecorded.CoppercontentinwatersampleIntheformula:ρ(Cu):