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X Series ICP-MS Training Course Introduction to ICP-MS theory and X Series ICP-MS PlasmaLab Analytical Method Development Dealing with interferences.

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Presentation on theme: "X Series ICP-MS Training Course Introduction to ICP-MS theory and X Series ICP-MS PlasmaLab Analytical Method Development Dealing with interferences."— Presentation transcript:

1 X Series ICP-MS Training Course Introduction to ICP-MS theory and X Series ICP-MS PlasmaLab Analytical Method Development Dealing with interferences

2 Application areas

3 Metals / Industrial Analysis of major, minor and trace elements Purity of fine metals Solution Analysis via nebulisation Solids Analysis via Laser Ablation Reagents required: 40% v/v/ Primar Nitric acid and deionised water No sample preparation required. Bulk or feature analysis can be performed on metals.

4 Nuclear Fuel quality certification Environmental and bioassay monitoring of low level actinides Precise and accurate isotope ratio measurement Signal to noise ratio needs to be maximized for ppq & sub ppq LOD’s. Use of high efficiency nebulisers. For waste minimization use of low flow nebulisers, e.g. PFA-50

5 Semiconductor Determination of low levels of impurities in ultra-pure process reagents Impurity analysis of wafers Transition metals suffer from Argon oxide and Argon nitride interferences, which are greatly reduced with the PlasmaScreen Plus and CCT options. Use ultra-clean glassware, cones etc. Recommended Accessories: USN and PFA-50, if low sample volume

6 Biological & Clinical Speciation of metals Elemental uptake and excretion studies Stable isotope tracer studies Analysis of salvia, serum, blood and urine CCT technique recommended to overcome interferences on key elements such as Cr, Fe, As, Se in heavy biological matrices

7 Geological Rocks, sediments and soils Direct solid analysis using Laser Ablation on: Individual minerals, thin section, isotope ratios, zonation studies, depth profiling. Oxide interferences within REE e.g. BaO on 151 Eu and 153 Eu, NdO on 150 Tb, 160 Gd and 162 Dy. Residual HClO 4 or saline matrices will interfere with Cr,V and As(ClO & ArCl interferences).

8 Environmental Analysis of drinking and waste water Seawater and marine life (shellfish, corals etc.) Analysis of industrial effluents Soil/sediment studies Transition metals suffer from Argon oxide and Argon nitride interferences, which are greatly reduced with the CCT option. Reagents required 40% v/v Primar Nitric acid and deionised water Sample dried into a digest ‘bomb’, if required.

9 Minimising contamination Laboratory environment Water quality Ultrapure reagents Handling of ultrapure reagents Selection of material for containers & cleaning procedures Sample and standard preparation

10 Tracing sources of contamination The Step-by-Step Approach Instrument blank Water blank Dilute acid blank Analysis blank

11 Causes of interferences

12 Interferences – mass spectroscopic

13 Interferences – non mass spectroscopic

14 ELEMENTI ISOTOPI in ICP-MS Isotopi : Atomi dello stesso elemento con differenti masse (stesso numero di protoni & elettroni ma diverso numero di neutroni) Mass : 55,9116 Mass : 52,0554 Isobaric Interference Mass 54 Isotope for Fe Isotope for Cr Isotopes for Iron Isotopes for Chromium Cr Fe

15 INTERFERENZE Le interferenze Molecolari e Isobariche vengono classificate come interferenze spettroscopiche - Interferenze Molecolari (poliatomiche): sono Ossidi ed Idruri, Specie poliatomiche Gli ossidi possono essere minimizzati attraverso il tuning, gli idruri mediante sistemi per l’abbattimento delle interferenze (CCT) -Interferenze Isobariche: questo tipo di interferenze sono dovute alla sovrapposizione di diversi isotopi

16 Interferences SpectrometerLenses (CCT) Ar +, N +, O +, N 2 +, O 2 +, Ar 2 +, etc. ArO +,ClO +,ArNa + etc. Ar + (0.1%) Ar diss.“metal”, H 2 0, HNO 3, HCI, etc. dry “metal” or metal-oxide, decomposing anions Metal Atoms Metal Ions (M + ) Conventional “Front-End” approaches to reduce interferences “Analyzer approach” to reduce or resolve interferences M o > M + + e - “Ionization potential”

17 ESEMPI DI INTERFERENZE SPETTROSCOPICHE Interferenze poliatomiche Interferenze da Ossidi, Idrossidi, Idruri e doppie cariche

18 Polyatomic peak overlaps  Causes/sources : solvent – Anions in sample – Cations in sample – Ar gas – Entrained air Signal suppression Ionisation suppression or enhancement  Causes/sources : Overloading plasma – Overloading nebuliser – Cone orifice issues – Unintended plasma cooling effects Elemental peak (isobaric) overlaps  Generally precludes the use of some isotopes if overlap exists Interferences Analyte portion of total measured signal Illustration of overlapping peaks Total measured signal = analyte + polyatomic

19 Correction equations Monoisotopic As in a Cl matrix Se (82) ArAr 40,40 ArAr 38,40 ArAr 36,40 ArCl 40,37 Se 77 ArCl 40,35 As 75 Therefore we can calculate the contribution of ArCl at 77

20 Correction equations Se (82) ArAr 40,40 ArAr 38,40 ArAr 36,40 ArCl 40,37 Se 77 ArCl 40,35 As 75 Se (77) = Se (82) x AbSe (77) AbSe (82) ArCl (77) = Int (77) - Se (77) ArCl (75) = ArCl (77) x Ab(ArCl (77) ) Ab(ArCl (75) ) As (75) = Int (75) - ArCl (75) Monoisotopic As in a Cl matrix Calculate 77 Se contribution at mass 77 from 82 Se Calculate 77 ArCl contribution at mass 77 from 77 Se Calculate ArCl contribution at mass 75 from 77 ArCl Calculate 75 As contribution from 75 ArCl

21 Instrument performance options But the X Series ICP-MS, does supply a few ‘hardware’ remedies for these problems….. PlasmaScreenPlus - a)‘cool’ screen operation - analysis of Li, Na, K, Ca, Fe b) ‘hot’ screen operation – enhances sensitivity while maintaining low background CCT - removal of polyatomics Xi – improves matrix tolerance and reduces polyatomics

22 Instrument performance options

23 PlasmaScreen Plus PlasmaScreen TM Torch - Grounded metal screen inserted between torch and load coil - Reliable automatic switching between ‘hot’ and ‘cool’ plasma conditions Cool screen conditions (~600 Watts) - Minimizes argon-based interferences i.e. 38 Ar 1 H +, 40 Ar 16 O +, 40 Ar Minimizes high backgrounds associated with easily ionizable elements i.e. Li, Na - ng/L LODs for Li, Na, Ca, K, Fe, Cr Hot screen operation - Enhanced sensitivity - Low background maintained - Improved detection limits

24 COOL PLASMA Caratteristiche RF a bassa potenza: w con nebulizzatore a flusso alto Temperatura del Plasma prossima a K Vantaggi Permette di determinare in ICP-MS elementi come Ca, Mg, Fe, Na, K, Cr, V Limitazioni Plasma non robusto: è necessario analizzare campioni nella medesima matrice Impossilità di analizzare elementi con alto potenziale di eccitazione/ionizazione ( As, Hg, Se)

25 CCT HEXAPOLE RODS SKIMMER CONE EXTRACTION LENS SAMPLE CONE Operating the ion guide with a suitable collision/reaction gas (in CCT mode)  Selective attenuation of polyatomic interference ions – 40 Ar 35 Cl, 40 Ar 12 C, 40 Ar 2 2+, 40 Ar 2 H, 38 Ar 1 H+, 40 Ar 16 O +, 40 Ar 2+ Innovative, user selectable CCT Plasma operated at normal power - Transmission of the analyte ions remains largely unaffected Ability to switch to CCT mode within sample

26 CCT - ArAr 59 Co + ArAr + H2H2 He 59 Co + ArAr (neutral) + H 2 +

27 CCT – analysis of iron 10ppb Fe - CCT Blank - CCT

28 Based on a multipole ion guide contained in a cell into which the collision cell gases flow; cell is located between the interface and the quadrupole analyser Hexapole or octopole ion guides are used Collision cell Split-flow high-compression turbo pump Cell Gas 1 Cell Gas 2 MFC 1MFC 2 DetectorCOLLISION CELL Rotary Pump Plasma Slide Valve Quadrupole

29 Based on a multipole ion guide contained in a cell into which the collision cell gases flow; cell is located between the interface and the quadrupole analyser Hexapole or octopole ion guides are used Collision cell Split-flow high-compression turbo pump Cell Gas 1 Cell Gas 2 MFC 1MFC 2 DetectorCOLLISION CELL Rotary Pump Plasma Slide Valve Quadrupole

30 Principi della tecnologia a cella di collisione Il fascio ionico viene iniettato in una cella pressurizzata - Tradizionalmente vengono impiegate miscele He, H 2 or a He/H 2 Gli ioni poliatomici collidono con il gas della celle e vengono dissociati nei loro componenti atomici, ioni etc Ar 1 H + / 39 K, 40 Ar + / 40 Ca, 40 Ar 12 C + / 52 Cr, 40 Ar 23 Na + / 63 Cu, 40 Ar 16 O + / 56 Fe, 40 Ar 35 Cl + / 75 As, 40 Ar 2+ / 80 Se La trasmissione degli ioni analiti attraverso la cella non viene praticamante influenzata Le condizioni di plasma ad alta temperartura vengono mantenute Ferro Argon Ossigeno Idrogeno ArO + Ar H2H2 H2O+H2O+ H2H2 H2H2 Fe +

31 CCT ED – Meccanismi possibili Meccanismi possibili  Dissociazione collisionale? – e.g. ArAr + + He = Ar + Ar + + He  Reazione chimica? – e.g. ArAr + + H 2 = ArH + ArH +  Trasferimento di carica? – e.g. ArAr + + H = ArAr + H +  Ritardo collisioneale e successiva flitrazione in termini di energia delle specie? – e.g. ArAr +* + He = ArAr + + He *

32 Solving the problem of cell generated interferences Subsequent collisions of cell-generated ions cause them to lose kinetic energy These ions (and also plasma derived polyatomic ions), with their larger collision cross section, lose more energy than the smaller analyte ions Can prevent these lower energy interfering ions from being detected by using an energy barrier between the cell and the quadrupole analyser – this is called (kinetic) energy discrimination (ED or KED)

33 How is energy discrimination set up? Changing collision cell and quadrupole bias voltages provides a simple way to set up the required energy barrier Polyatomic ions from plasma or cell reaction products have insufficient energy to pass through the energy discrimination barrier Potential Position Without ED With ED Potential Barrier Collision CellLensesQuadrupole -2V -9V -18V -14V Analyte Ion Isobaric Polyatomic ion Key

34 The power of energy discrimination (1) In environmental and clinical samples, containing Cl and Ca, 75 As is interfered by 40 Ar 35 Cl + and to a lesser extent, 40 Ca 35 Cl + Collision cells are effective for removing these interferences, however, if ED is not used, a large signal is still observed on 75 As This signal does not match the 3:1 m/z 75 to m/z 77 ratio expected if the interference is Cl - related, so it must be another species If Ca is not present, the interference is not observed, so it must be related to Ca Mass 75 = 17,000 cps (Mass 77 = 2,000cps) Scan of 100ppm Ca, collision cell without ED

35 The power of energy discrimination (2) The interference is believed to be CaOH(H 2 O) + or CaO(H 3 O) +, formed from collision, then reaction, between CaOH + and H 2 O in the cell As the Ca-species forms in the cell it’s energy is immediately reduced relative to the As+ analyte ion; further collisions as it passes through the cell reduce the energy further Applying a few volts of ED results in elimination of the species As+ is still transmitted to the quadrupole and can be determined to low ppt levels Mass 75 = 6 cps Scan of 100ppm Ca, collision cell with 2V ED

36 The power of energy discrimination (2) 1ppb 75 As = 300 cps Scan of 100ppm Ca + 1ppb As, collision cell with 2V ED The interference is believed to be CaOH(H 2 O) + or CaO(H 3 O) +, formed from collision, then reaction, between CaOH + and H 2 O in the cell As the Ca-species forms in the cell it’s energy is immediately reduced relative to the As+ analyte ion; further collisions as it passes through the cell reduce the energy further Applying a few volts of ED results in elimination of the species As+ is still transmitted to the quadrupole and can be determined to low ppt levels

37 1% HNO 3 Blank 1ppb Fe 1% HNO 3 Blank Quadrupole – Standard Mode Quadrupole – CCT Mode (H 2 /He) Reduction of 40 Ar 16 O + and Ar 2 + using the collision cell Quadrupole – Standard Mode Quadrupole – CCT Mode (H 2 /He) 10ppb Se 1% HNO 3 Blank 10ppb Se

38 Collision cell ICP-MS Fe / Se calibration performance 80 Se ( 40 Ar 2 + attenuated) Fe 1.0Detection limit (3σ, n = 5) (ppt) 4.3BEC (ppt) Correlation coefficient 1648Sensitivity (cps/ppb) 80 SeParameter 56 Fe ( 40 Ar 16 O + attenuated) Sample matrix = 2% HNO 3, 8% H 2 in He collision gas used

39 Why use oxygen as a collision / reaction gas? Some interferences cannot be efficiently removed using 'standard' cell gases (e.g. He, H 2, NH 3 ) Some interfered analytes react (along with their interferences), with certain cell gases (e.g. NH 3 ) –Lose analyte sensitivity; degrade detection limit Kinetic energy discrimination (KED) or bandpass application sometimes not sufficiently effective –Interference suppression results in too much sensitivity loss –BEC's and detection limits not low enough for the analytical requirement

40 XSeries II – New Proof Data - 1 Fast Cd and Pb in whole blood analysis Blood reference materials measured; diluted 1:50 for analysis Standard addition calibration on one sample used to quantify other samples  Unique ability for Thermo! Ideal approach for biomedical samples! Autosampler probe-to-wash-early function used to maximise throughput  Unique for Thermo! Sample throughput = 51 per hour, or more than 400 per 8 hour day! ± ± 0.5Bio Rad Reference 208 Pb (ppb) Reference 111 Cd (ppb) 254 ± ± 0.4Bio Rad ± ± 0.5Seronorm blood 2 Measured 208 Pb (ppb) Measured 111 Cd (ppb) Sample identity 111 Cd 208 Pb

41 XSeries II – New Proof Data - 2 Urine reference material diluted 1:20 with 1% (v/v) HNO 3 for analysis; spike recovery (0.50 ppb Cd) performed on sample doped with Mo (5 ppm) Standard addition calibration on the sample used to quantify other samples Samples run in standard and collision cell mode with O 2 in the cell  O 2 promotes MoO + to higher Mo oxides; Cd does not react Cd in urine in the presence of Mo (removing the MoO interference) 96 Mo 16 O + 95 Mo 16 O + Mo interference Detection limit 3σ (ppb) Conc. (ppb) Standard modeCollision cell mode (O 2 ) Spiked Cd value (ppb)Isotope Detection limit 3σ (ppb) Cd Cd Conc. (ppb) O 2 in the cell completely removes the MoO interference! Without O2 the interference is large

42 Detection of Pt in 10 ppm Hf solutions The problems:  HfO + and HfOH + interferences on all Pt isotopes (m/z 190 to 198)  m/z 190 and 198 interferences low abundance but 190 Pt very low abundance (0.01%) and 198 Pt also low (7.2%)  Must suppress HfO + / HfOH + interferences on most abundant remaining Pt isotopes ( 194 Pt, 195 Pt and 196 Pt) The proposed solution:  Use O 2 as the collision gas, to promote formation of higher Hf oxides / hydroxides  Pt less reactive with O 2 HfO +, HfOH + interferences, 10ppm Hf 179 Hf 16 O + = 3 Mcps Pt isotopes, 12ppb Pt 195 Pt + = 250 Kcps

43 Pt in 10 ppm Hf, standard mode and O 2 data Detection limit 3σ (ppb) 467 * 154 * 281 * BEC (ppb) * Standard modeStandard BEC / collision cell BEC Collision cell mode (O 2 ) # Hf interference Isotop e Detection limit 3σ (ppb) Hf 16 O Pt Hf 16 O +195 Pt Hf 16 O +194 Pt BEC (ppb) * estimated using the 198 Pt (linear) calibration sensitivity # O 2 flow rate = 2.7 mL/min, non-KED 195 Pt standard mode 195 Pt collision cell mode (O 2 )

44 Detection of Hg in 10 ppm W solutions The problems:  WO + and WOH + interferences on all Hg isotopes (m/z 196 to 204)  m/z 196 and 204 interferences low abundance, but 196 Hg very low abundance (0.14%) and 204 Hg also low (6.8%)  Also have 204 Pb interference on 204 Hg  Must suppress WO + / WOH + interferences on most abundant remaining Hg isotopes ( 198 Hg, 199 Hg, 200 Hg, 201 Hg and 202 Hg) The proposed solution:  Use O 2 as the collision gas, to promote formation of higher W oxides / hydroxides  Hg less reactive with O 2 WO +, WOH + interferences, 10ppm W 184 W 16 O + = 2.4 Mcps Hg isotopes, 20ppb Hg 200 Hg + = 140 Kcps

45 Hg in 10 ppm W, standard mode and O 2 data * 184 W 16 O +200 Hg * 183 W 16 O +199 Hg Detection limit 3σ (ppb) 247 * * BEC (ppb) * Standard modeStandard BEC / collision cell BEC Collision cell mode (O 2 ) # W interference Isotop e Detection limit 3σ (ppb) W 16 O Hg W 16 O 1 H +201 Hg W 16 O +198 Hg BEC (ppb) * estimated using the 201 Hg (linear) calibration sensitivity # O 2 flow rate = 3.4 mL/min, non-KED 200 Hg standard mode 200 Hg collision cell mode (O 2 )

46 Detection of Cu and Zn in 10 ppm Ti solutions The problems:  TiO + (and TiOH + ) interferences on all Cu and Zn isotopes (m/z 63 to 70)  m/z 68 and 70 interferences low abundance but 70 Zn also low (0.6%)  68 Zn most useful in absence of collision cell  Must suppress TiO + / TiOH + interferences on Cu and most abundant Zn isotopes The proposed solutions:  Use O 2 as the collision gas to try to promote formation of higher Ti oxides / hydroxides  Compare with kinetic energy discrimination (KED) approach, using H 2 /He collision gas TiO + interferences, 10ppm Ti Cu / Zn isotopes, 10ppb Cu / Zn 47 Ti 16 O + = 13 Kcps 48 Ti 16 O + = 130 Kcps 49 Ti 16 O + = 11 Kcps 63 Cu + = 85 Kcps 64 Zn + = 68 Kcps 65 Cu + = 42 Kcps

47 Cu, Zn in 10 ppm Ti, standard mode and O 2 data 64 Zn standard mode 64 Zn collision cell mode (O 2 ) Ti 18 O + 68 Zn Ti 16 O + 66 Zn Detection limit 3σ (ppb) BEC (ppb) Standard modeStandard BEC / collision cell BEC Collision cell mode (O 2 ) # Ti interference Isotop e Detection limit 3σ (ppb) Ti 16 O + 64 Zn Ti 16 O +65 Cu Ti 16 O +63 Cu BEC (ppb) # O 2 flow rate = 7.0 mL/min, non-KED

48 Cu, Zn in 10 ppm Ti, standard mode and H 2 /He KED data 64 Zn standard mode 64 Zn collision cell mode H 2 /He KED Ti 18 O + 68 Zn Ti 16 O + 66 Zn Detection limit 3σ (ppb) BEC (ppb) Standard modeStandard BEC / collision cell BEC Collision cell (KED) mode Ti interference Isotop e Detection limit 3σ (ppb) Ti 16 O + 64 Zn Ti 16 O +65 Cu Ti 16 O +63 Cu BEC (ppb) Data obtained using a 8% H 2 /He gas flow of 5.5 ml/min and a KED barrier of 3.5V

49 4 Standard Reference Waters were analyzed as ‘unknown’ samples over a 10- hour period Wide range of typical environmental analytes were measured - 30 analytes, 55 isotopes Several analytes had associated interference problems…. CCT ED – Evaluation of Performance

50 Uptake 25s Experimental - analytical profile Analytes Settle Delay 30s Settle Delay 30s Standard Mode 3x18s reps Wash 25s Total Time Per Sample = 3 minutes, 45 seconds Time Profile V Cr NH 3 /He 3x1.6s reps Li Be Na Rb Sr Rb Mo Ag Cd Sn Cs Ba Tl Pb U Mg Al K Ca Cr Fe Mn Ni Cu Zn Ga As Se H 2 /He 3x18s reps

51 Experimental - procedure Calibration:  Blank  1ppb multi-element solution  10ppb multi-element solution 4 reference water samples analysed as QC checks 12 times over a period of 10 hours against 12 different calibrations  NIST 1640 diluted 1+9 and spiked to 2% HCl  CNRC SLRS-2 spiked to 2% HCl  CNRC SLRS-3 spiked to 2% HCl  CNRC SLRS-4 diluted 1+1 and spiked to 2% HCl Detection limits calculated by running 10-replicate blank samples 12 times against 12 different calibrations

52 Results: stability in different measurement modes - 10ppb standard 10ppb Solution No internal standard correction Each isotope measured in a different mode, switching from NH 3 to H 2 to Std mode in- sample

53 Results: stability of real sample in different modes Sample diluted 1+9 and spiked to 2% HCl

54 Results – Method detection limits (  g/L) Based on 3s on 12x10replicates of blank, each from a new calibration

55 Results – accuracy of reference samples All concentrations in  g/L n=12

56 Results – accuracy of reference samples

57 Analysis of Seawater Reference Materials Direct analysis of seawater is challenging:  Extreme matrix  Severe interferences  Ultra trace analyte concentrations Analysed against a matched external calibration H 2 /He KED CCT mode used for ALL analytes Rapid method (~3 min/sample) No gas switching required No instrument settings switching required Easy set-up

58 XSeries II – New Proof Data (ppt)

59

60

61 CCT ED Evaluation of Performance - Summary Provides Ease of Set-up –Auto-tune, performance reports allow fully automated set-up and analysis Ultimate Flexibility –Single mode runs ( e.g.. Seawater example) Fast analysis –Mode Switching runs Ultimate Detection Limits Handles the most extreme matrices (seawater) to give interference free measurements on difficult analytes Retains excellent stability and accuracy


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