Cost-effective Trace Element Analysis with TXRF

Transcription

1 1 Cost-effective Trace Element Analysis with TXRF

2 Welcome Today s Topics Introduction to XRF and TXRF The S2 PICOFOX benchtop TXRF system Why wait for sample prep? Application studies Environment Medical/Pharma Mining Summary Interactive Q & A Speakers Your Host Alexander Seyfarth Product Manager XRF Elemental & Process Analysis Bruker AXS Dr. Michael Rider, Applications Scientist XRF, Madison, WI, USA Dr. Armin Gross, Global Product Manager TXRF, Berlin, Germany 2

3 3 Introduction to XRF and TXRF Michael Rider

4 Principles of X-ray Fluorescence (XRF) Spectroscopy An X-ray quantum hits an inner shell electron in a (sample) atom. The electron is removed leaving the atom in an excited state. 2. The missing inner shell electron is replaced by an electron from an outer shell. 3. The energy difference between the inner and outer shell is balanced by the emission of a photon quantum (fluorescence radiation). 3 4

5 Principles of X-ray Fluorescence Spectroscopy The energy, and therefore the wavelength, of the X-ray fluorescence radiation is characteristic for the different chemical elements. QUALITATIVE ANALYSIS The intensity of the X-ray fluorescence radiation is, in first approximation, proportional to the element concentration. QUANTITATIVE ANALYSIS Low z High z 5

6 Principles of X-ray Fluorescence Spectroscopy Common XRF optics Detector X-ray tube Sample Beam angle: 45 o / 45 o 6

7 Principles of X-ray Fluorescence Spectroscopy Samples for common XRF spectrometry (EDXRF and WDXRF): Solids (cut, polished and put into suitable shape) Powders (as pressed pellets, fused beads or loose powders in liquid cups) Liquids (in liquid cups) Necessary sample amount: 1-10 g 7

8 Principles of Total Reflection X-ray Fluorescence (TXRF) Spectroscopy Total reflection X-ray fluorescence spectroscopy Detector X-ray tube Sample carrier Beam angle: 0 o / 90 o 8

9 Principles of Total Reflection X-ray Fluorescence Spectroscopy Samples: Powders: direct preparation or as a suspension Liquids: direct preparation Always as a thin film, micro fragment or suspension of a powder Necessary sample amount: Low µg / µl range 9

10 Principles of X-ray Fluorescence Spectroscopy Quantification in common X-ray fluorescence spectroscopy absorption of primary beam and fluorescence radiation secondary fluorescence enhancement Ii = f ( ci, cj) and ci = f ( Ii, cj) 10

11 Principles of Total Reflection X-ray Fluorescence Spectroscopy Quantification in total reflection X-ray fluorescence spectroscopy In TXRF the samples are prepared as thin films or layers. Therefore matrix effects are negligible QUANTIFICATION IS POSSIBLE BY : Known concentration and net intensity of an internal standard element Net intensity of element lines Sensitivity of the instrument for element lines (energy-dependent) 11

12 Principles of X-ray Fluorescence Spectroscopy Negligible absorption of primary beam and fluorescence radiation Ii = f ( ci ) ci = f ( Ii ) Negligible secondary fluorescence enhancement 12

13 Setup and Working Principle of the S2 PICOFOX Monochromator Detector X-ray source Sample Sample carrier Sample changer 13

14 The S2 PICOFOX 14

15 15 Why Wait for Sample Prep! Michael Rider

16 Audience Poll Please use your mouse to answer the question on your screen: How do you currently treat your samples before analysis? (Check all that apply.) No treatment Grinding Dissolving Dilution Extraction Digestion 16

17 TXRF Sample Preparation Liquid Sample Pipette µl of sample. Dilute if needed. Add single-element standard solution Homogenize Transfer to sample carrier Dry 17

18 TXRF Sample Preparation Solid Sample Micro-particle Grind if needed Use Q-tip to deposit on substrate Add singleelement internal standard solution (or skip if one element is known) Dry 18

19 TXRF Sample Preparation Solid Sample Suspension Grind Weigh out mg Suspend in about 2.5 ml of suspension solution Add single-element internal standard solution Pipette 10 µl of the suspension and dry 19

20 TXRF Sample Preparation Digested Sample Grind if needed Weigh out mg Digest sample Transfer aliquot of sample Dilute if very high in mineral content 20

21 TXRF Sample Preparation Digested Sample Pipette µl of sample Add single-element standard solution Homogenize Transfer to sample carrier Dry 21

22 Environmental, Medical and Pharmaceutical Applications Dr. Armin Gross 22

23 S2 PICOFOX Application Overview Environmental research and monitoring Description of the application Sewage & fresh water analysis Aerosol analysis Filter analysis Contaminated soils Benefit by TXRF on-site analysis ppb detection limits fast and simple sample preparation direct sampling on sample carrier detection limits < 1 ng/m³ direct measurements (qualitatively) simple extraction for quantification on-site analysis screening for contaminated hot spots 23

24 Application Sewage & Fresh Water Analysis Analytical task: Control of threshold values for heavy metals in: raw and digested sewage samples fresh water Sample preparation dilution (raw sewage) remark: filtration and separate analysis of filtrate is possible internal standardization preparation (homogenization, vacuum drying) of 10 µl sample solution Measurement measurement time: 1000 s 24

25 Application Sewage & Fresh Water Analysis digested Results 1000 raw (undiluted) raw (diluted) Ca TXRF values (mg/l) Pb Ni Cr,Mn,Fe Cu S,P,K 0 Hg ICP-OES values (mg/l) 25

26 Application Sewage & Fresh Water Analysis Detection limits 1000 s measurement time standard configuration Detection limit (µg/l) 1000 ppb digested raw PITTCON 2008! high efficiency module for higher sensitivity 30 mm 2 XFlash Atomic number 26

27 S2 PICOFOX Application Overview Medical and pharmaceutical Description of the application Blood, serum and urine Impurities in nutrients/pharma Authenticity Heavy Metals Analysis Benefit by TXRF ppb detection limits fast and simple sample preparation comparable results than AAS simultaneous analysis element fingerprint ease of sample prep USP requirements (10 ppm) readily achievable mobile use USP = US Pharmacopia 27

28 S2 PICOFOX Blood, Serum, Urine and Peptides Life science: Blood, serum and urine analysis analysis of nutrition-relevant elements (Cu, Fe, Zn, Se) analysis of other e.g. toxic elements and Pt (chemotherapy) easy sample preparation better stability compared to AAS and ICP-OES 28

29 S2 PICOFOX Blood Analysis Sample preparation: Serum 1:10 dilution with water (p.a. grade) Addition of Ga for internal standardization Full blood 1:1 dilution with water (p.a. grade) Addition of Ga for internal standardization 29

30 ens2 PICOFOX Blood Analysis Serum reference standards, diluted, measurement time: 600 s Reference values (µg/l)fczs good correlation for Cu, Zn and Se overestimation of Fe improved calibration curve required* Remark: Confidence level of reference values is up to 35 % (!) eu TXRF values (µg/l) 30

31 S2 PICOFOX Blood Analysis Full blood reference standards, diluted, measurement time: 600 s S10000 KCaRb1000 SrPbSeCu100 ZnFe Reference values (µg/l)p application of optimized blood calibration Very good correlation for Fe, Cu, Zn, Se and others TXRF values (µg/l) 31

32 S2 PICOFOX Blood Analysis Reproducibility Serum (ClinCheck L2) Whole blood (Seronorm L2) Element Unit TXRF s (n=5) Reference 1) s TXRF s (n=5) Reference 2) s Fe mg/l 440 7, ,9 0,09 1,964 0,20 Cu µg/l 66 2,2 62 2, Zn µg/l 501 4, , Se µg/l 12 0, , ) : Sector-Field Inductively-Coupled Plasma Mass Spectroscopy 2) : Atomic Adsorption Spectroscopy 32

33 Application Pharmaceutical Samples Purity Control Example: Raw material NaCl Analytical task: analysis of impurities, especially with regard to the limit value of 1 mg/kg for As, in pure NaCl Samples NaCl (p.a. grade), Carl Roth GmbH As: < 0.4 mg/kg same sample, spiked with As 33

34 Application Pharmaceuticals - Purity Control Recovery results: Measured values As (mg/kg) 5,0 4,0 3,0 2,0 1,0 y = 1,1157x + 0,0986 R 2 = 0,9972 Trace element concentrations of Ca, Ti, Cr, Fe, Ni, Cu, Zn and Br were determined simultaneously 0,0 0,0 1,0 2,0 3,0 4,0 5,0 Spiked As (mg/kg) 34

35 Application Pharmaceuticals Purity Control Detection limits 600 sec Conc. LLD (mg/l) Ca 2,4 0,57 Ti 1,8 0,25 Cr 0,85 0,17 Fe 11 0,13 Ni 0,29 0,09 Cu 0,34 0,08 Zn 0,33 0,07 As 1,2 0,07 Se (i.s.) 20 0,07 Br 19 0,08 35

36 36 More Applications Alexander Seyfarth

37 Application Reading Tea Leaves Elemental content such as Pb, Tl, As and Cd is regulated to be less than 10 ppm organic labeling might also imply that no preservation (fumigation) was performed Inspection of the leaves by a) Screening of pulverized material b) Precision analysis on digested material 37

38 Application Food/Nutrients Tea Leaves Precision analysis on hot samples: Microwave digestion, digested solution measured both on TXRF and Graphite Furnace AAS identical results for Pb with both techniques TXRF found Br as well, indication of fumigated by methyl bromide Screening for more than one element More determinations per sample for a service lab No calibration needed! 38

39 S2 PICOFOX Digging for Gold Fortunes are made using exploration techniques: Description of the application PGE and indicator elements Benefit by TXRF simple qualitative analysis direct or digested sample quantification ppb levels mobile use in trailer simultaneous determination faster than AAS/ICP 39

40 S2 PICOFOX Exploration Samples Analytical task: Check for trace elements in directly prepared sediment samples Sample preparation fine grinding to less than 10 μm internal standardization mixing slurry prep on substrate Measurement measurement time: 600 s 40

41 S2 PICOFOX Exploration Samples 41

42 S2 PICOFOX Au and Pt in Exploration Good correlation between digested diluted, digested and raw samples Fit for purpose choice Aqua regia or HNO 3 digestions can be directly applied on the substrate and measured after drying High loaded solutions can be diluted and measured Fit for purpose choice Preparation can yield clues about the dissemination of the elements 42

43 S2 PICOFOX CRM SARM7-B Spike: 0 mg/kg Spike: 10 mg/kg Spike: 20 mg/kg Spike: 30 mg/kg Spike: 40 mg/kg Ref. (mg/kg) Conc. (mg/kg) Conc. (mg/kg) Conc. (mg/kg) Conc. (mg/kg) Conc. (mg/kg) Pt 3.74 not det / / / /- 2.8 Au 0.27 not det / / / / Pt 3σ LLD 2.8 mg/kg Au 3σ LLD 1.5 mg/kg Higher LLD due to high Zn matrix interference 43

44 S2 PICOFOX CRM SARM7-B Pt Au TXRF value (mg/kg) Spiked reference value (mg/kg) 44

45 PGE Analysis After NiS Melt-Digestion Rh Ir Pt Au automotive catalysts TXRF [µg/kg] geological samples 0,1 0, ICP-MS [µg/kg] 45

46 S2 PICOFOX GEO applications Suspensions can be tested for clay fraction metal loading Fractions can be measured based on density difference Allows flotation recovery assessments Optimization of flotation Trace element determination complimentary to majors and minor elements by WDXRF Brine and hydrothermal solutions Fluid Inclusion Brine analysis For applications such as IODP IDDP System can be placed in mobile unit Operated in remote locations 46

47 Applications From Geo to Nano Task determination of the element ratios in ZnS-coated CdSe nanoparticles Analytical challenges R&D only smallest (µg-range) sample amounts available need to reused! demand for non-destructive analysis sample material is almost insoluble: NO DIGESTION was possible Application possible with TXRF! No reference material! 47

48 Application Characterization of Nanoparticles Results Element Ratios of Nano Particles Measured ratios of 3 samples versus target value ( ) S2 PICOFOX Ratio (wt.-%) Sample 1 Sample 2 Sample 3 Standardless analysis Zn/S Cd/Se Zn/Cd 48

49 Applications Summary - 3σ Detection Limits Low background low detection limits "ppt" "ppb" "ppm" fresh water sewage, mining sol. soil glass, wash coats wine food pharma blood, serum, urine Measurement time: 1000s peptides 49

50 50 Let s Compare... Armin Gross

51 Comparison TXRF versus AAS & ICP-OES Sample types TXRF ICP-OES AAS Direct analysis of solids Qualitative, quantitative * not possible GF-AAS only Sample amount ng to µg range mg range mg range GF-AAS µg range 51

52 Comparison TXRF versus AAS & ICP-OES During operation TXRF ICP-OES AAS Multielement analysis Yes Yes Sequential only Standardless Yes (with restrictions) Meas. time s <10 s per element <10 s per element Yes No Calibration Internal standardization External, elementspecific, to be updated External, elementspecific, to be updated 52

53 Comparison TXRF versus AAS & ICP-OES Cost of operation TXRF ICP-OES AAS Consumables (X-ray tube) (Nebulizer parts) Cathode lamps Power consumption Low (150 W) High (HF generator kw) Low Water consumption none > 0,5 l/min ~1.5 l/min (GF only) Gas consumption none Carrier/burning gas (Ar, N 2 ), l/min FAAS: burning gas (C 2 H 2 ), l/min GF: Carrier gas (Ar,N 2 ) 53

54 Comparison TXRF versus AAS & ICP-OES The S2 PICOFOX can be an alternative to AAS and/or a complement for existing ICP-OES systems Major benefits of the S2 PICOFOX flexibility with regard to sample types easy multi-element analysis without external calibration low maintenance and operating costs small size of the system (mobile and remote location use) 54

55 Any Questions? Please type any questions you may have for any of our speakers in the Q&A box and then click Send. 55

56 Thank you for attending! Please take a moment to complete the brief survey on your screen. Your feedback is very important to us. Copies of this presentation and related TXRF resource materials will be ed to you. 56

57 Meet us at: SME: Feb in Salt Lake City, UT PITTCON: Mar 1-7 in New Orleans LA TMS: Mar in New Orleans LA IFT: June 28th-Jul 1st in New Orleans, LA Denver X-ray Conference: Aug 4-8 in Denver, CO XRF for YOU Seminar Northwest Seattle, Washington, Apr 25 A free 1-day seminar on theory, instrumentation, preparation and application of EDXRF and WDXRF 57