Principle of ICP Optical Emission Spectrometry (ICP-OES)

ICP, abbreviation for Inductively Coupled Plasma, is one method of optical emission spectrometry. When plasma energy is given to an analysis sample from outside ... Skiptomaincontent Search Global HitachiGroupProducts&Services HitachiGroupCorporateInformation GlobalNetwork Sitemap ContactUs Products&Services AboutUs Support TOP TechnicalSupport:ICPAnalysis PrincipleofICPAnalysis PrincipleofICPOpticalEmissionSpectrometry(ICP-OES) PrincipleofICPOpticalEmissionSpectrometry(ICP-OES) 1.Introduction Ithasbeen25yearssinceICPopticalemissionspectrophotometers(ICP-OES)begantobewidelyused,andisnowoneofthemostversatilemethodsofinorganicanalysis.Itsfeaturesareoftencomparedtoatomicabsorptionspectrophotometers.Comparedtoatomicabsorptionspectrophotometers,inwhichtheexcitationtemperatureofair-acetyleneflamemeasures2000to3000K,theexcitationtemperatureofargonICPis5000to7000K,whichefficientlyexcitesmanyelements.Also,usinginertgas(argon)makesoxidesandnitrideshardertobegenerated. 2.ICPOpticalEmissionSpectrometryPrinciple ICP,abbreviationforInductivelyCoupledPlasma,isonemethodofopticalemissionspectrometry.Whenplasmaenergyisgiventoananalysissamplefromoutside,thecomponentelements(atoms)areexcited.Whentheexcitedatomsreturntolowenergyposition,emissionrays(spectrumrays)arereleasedandtheemissionraysthatcorrespondtothephotonwavelengtharemeasured.Theelementtypeisdeterminedbasedonthepositionofthephotonrays,andthecontentofeachelementisdeterminedbasedontherays'intensity. Togenerateplasma,first,argongasissuppliedtotorchcoil,andhighfrequencyelectriccurrentisappliedtotheworkcoilatthetipofthetorchtube.Usingtheelectromagneticfieldcreatedinthetorchtubebythehighfrequencycurrent,argongasisionizedandplasmaisgenerated.Thisplasmahashighelectrondensityandtemperature(10000K)andthisenergyisusedintheexcitation-emissionofthesample.Solutionsamplesareintroducedintotheplasmainanatomizedstatethroughthenarrowtubeinthecenterofthetorchtube. 3.AnalyticalChemicalFeaturesofICP-OES ThefollowingfeaturesofICP-OESdistinguishitfromatomicabsorptionspectrophotometersusedforsimilarpurposes. Simultaneous,sequentialanalysisofmultipleelementspossible Widelinearregionofanalyticalcurve Fewchemicalinterferenceorionizationinterference,makinganalysisofhigh-matrixsamplespossible Highsensitivity(lowlimitofdetectionformajorityofelementsis10ppborlower) Highnumberofmeasurableelements-elementsthataredifficulttoanalyzeinatomicabsorptionspectrometrysuchasZr,Ta,rareearth,PandBcanbeeasilyanalyzed Stable Themajorityoftheabovefeaturesarederivedfromthestructureandcharacteristicsofthelightsourceplasma. 4.Equipment EquipmentforICPopticalemissionspectrometryconsistsofalightsourceunit,aspectrophotometer,adetectorandadataprocessingunit.ThereareseveraltypesofequipmentbasedondifferencesintheSpectrophotometerandthedetector.ThemostcommontypeisshowninFigure1. 1)Sequentialtype AspectrophotometerwithaCzerny-Turnermonochrometor,andadetectorwithaphotomultiplierismostcommonforthistype.Withthisequipment,programmedwavelengthofthespectrophotometerisconsecutivelyvariedtomeasuremultipleelements.Thiscausesratherlongmeasuringtime,however,withitshighresolutionspectrophotometers,itisfavorableformeasurementofhigh-matrixsamples. Figure1:SequentialTypeICP-OES 2)SimultaneousType Thistypetypicallyusesanechellecrossdisperserinspectrophotometersandsemi-conductordetectorsuchasCCDforthedetector.Echellecrossdisperserdisperseslightofmeasurablewavelengthrangetwo-dimensionallybycombiningprismandechellediffractiongrating.CombinationofechellecrossdisperserandaCCDdetectorenablesmulti-elementmeasurementatanywavelength.Themostnotablefeatureofthisequipmentisthehigh-speedmeasurement,providinginformationonall72measurableelementsinmeasurementsof1to2minutesnormally. Figure2:SimultaneousICP-OES 5.Applications 3)SteelAnalysis OnemajorapplicationfieldofICPopticalemissionspectrometryismaterialanalysis.Thebelowexampleisananalysisofasteelsample. * Equipment:SequentialTypeICP-OES,SPS3000 * Sample:JSSStandardSteelSample150,0.5gdissolvedin100mlmixedacidofchloricacidandnitricacid. * Standardsolution:0.5gpureiron(99.99%),dissolvedinto100mlsolutionisusedasblank,andthestandardcurveiscreatedbystandardsolutionsof8measuredelements(matrixmatching). * Analysisconditions:Withahigh-matrixsamplesuchasthis,spectraloverlapwiththematrixelement(ironinthiscase)occurs,sothespectralprofileisinspectedandthemostsuitableanalysiswavelengthischosenformeasurement. * Analysisresult:Theresultsfromthe3measuredsamplesandthecertifiedvalueofthestandardsampleisshownonthechart,showingextremelygoodmatches. Chart1:Analysisresultofhightensilestructuralsteelseries Viewtable Sample 500-2 501-2 502-2 Element Certifiedvalue Measuredvalue Certifiedvalue Measuredvalue Certifiedvalue Measuredvalue Si 0.29 0.29 0.27 0.22 0.26 0.22 Mn 0.49 0.50 0.74 0.74 0.70 0.70 P 0.025 0.025 0.024 0.024 0.019 0.019 Ni 0.10 0.10 0.062 0.059 0.050 0.046 Cr 1.10 1.11 1.03 1.04 1.00 1.00 Mo 0.19 0.19 0.17 0.17 0.18 0.17 Cu 0.12 0.12 0.10 0.11 0.068 0.068 V 0.006 0.007 0.007 0.007 0.004 0.004 unit:% 2)BastnasiteAnalysis Bastnasiteisamineraloflanthaniderareearthtype.Therearemanyissueswithanalyzingrareearthwithatomicabsorptionspectrophotometers,suchasdifficultytoobtainalightsourcelampanddifficultywithatomizationduetooxideseasilygeneratedfromrareearths,buttheseproblemsareeliminatedforthemostpartwithICP-OES,whichiswidelyusedinthisfield.Onemajordifficultywithanalyzingrareearthsisthattheytendtohaveahighnumberofemissionraysandhasahighpossibilityofinterferencebynearbyraysontheanalysiswavelength. * Analysisconditions:0.5gBastnasiteisdissolvedinto100mlwithhydrofluoricacid,nitricacidandhydrogenperoxidesolution. * Analysisresult:Analysisofnon-rareearthandrareearthelementsisshownonthechartbelow.Quantitativedeterminationisconductedfrom30%concentrationceriumoxideto0.11%europiumoxide. Chart2:AnalysisresultofBastnasite unit:% 3)Hairanalysis Humanhairhasattractedattentionbecauseitisthoughttocontainaperson'shealthhistoryonsomelevelandisthoughttoactasanexcretoryorganforheavymetalinthebody.However,thereareproblemsbecausetherearefewusablesamplesandknowledgeaboutmultipleelementsisrequired.Withsimultaneousanalysisequipment,wecancollectusefulinformationwithasmallamountofsample. * Equipment:SimultaneousICP-OES,Vista-PRO * Sample:Afterwashing,0.5gofhairismeasured,andthenresolvedinadecompositionvesselwithnitricacidinto10mlsolution. Partialspectralprofileandanalysisresultsshownbelow. AnalysisiResult unit:µg/g 6.Conclusion ICPopticalemissionspectrometryisnowhighlyratedasamultipurposeanalysistechniqueandthereareover2,000unitsofICP-OESinuseinJapan.Itiswellregardedasanenvironmentalmeasurementtechnique,alongwithatomicabsorptionspectrometryandICPmassspectrometry,anditsuseisexpectedtoexpandevenfurtherinthefuture. pagetop TechnicalSupport:AnalyticalSystemsTechnicalSupport:ThermalAnalysisTechnicalSupport:HighPerformanceLiquidChromatograph（HPLC）TechnicalSupport:Spectrophotometers(UV-Vis/NIR,FL)TechnicalSupport:AtomicAbsorptionSpectrophotometer(AAS)TechnicalSupport:ICPAnalysisPrincipleofICPAnalysisTechnicalSupport:XRFAnalysis TermsofUse PrivacyPolicy ©HitachiHigh-TechCorporation.2001,2021.Allrightsreserved.