Analisi di Fluorescenza X a dispersione di energia Tradizionale ed in Riflessione Totale

1. Analisi di Fluorescenza X a dispersione di energia Tradizionale ed in Riflessione Totale (EDXRF e TXRF)

2. The EM spectrum – X-Rays 400 keV 40 keV 1 keV 40 eV

3. Elastic (Rayleigh) Scattering Interactions of X-Rays with matter Sample X-ray Source Inelastic (Compton) Scattering Photoelectric absorption

4. Photoelectron Incident photon Fluorescence photon X-ray fluorescence

5. Photoelectron Incident photon Auger electron Competition: Auger effect

6. Fluorescence yield

7. Transition probabilities Germanium

8. Ag K Fe K X-Ray line families - K

9. X-Ray line families - L Pb L

10. Typical energy dispersive set-up Pulse height discriminator ADC

11. TXRF Conventional EDXRF Energy-dispersive detector Energy-dispersive detector X-ray tube X-ray tube Primary beam Fluorescence radiation Fluorescence radiation Totally reflected beam Sample on Optical flat Sample TXRF and EDXRF geometries Comparison shows a difference in the geometric grouping of excitation and detection units

12. The XRF quantification problem enhancement absorption

13. The XRF quantification problem Monochromatic

14. Thin layer approximation No dependence on other elements (matrix)

15. EDX detector Incident X-ray beam Reflected X-ray beam n (x-ray range ) = 1-  - i Reflector  ~ 10-6  ~ 10-8 • Thin sample layer deposited on a reflector • The total reflection effect makes the sample support “almost invisible”  critical   2   critical (Si, 17.5 keV) = 0.1° = 1.75 mrad TXRF

16. Incident beam Reflected beam Refracted beam TXRF basics Quartz reflector Mo K radiation reflectivity transmittivity

17. TXRF basics Quartz reflector Mo K radiation Line intensity IL ( 1 + R ) Background IB ( 1 - R ) sin

18. Detection limits

19. Easy quantification - Taking ratios

20. Internal standard – relative sensitivities Compare with theory CALIBRATE QUANTIFY UNKNOWNS

21. Mo Ka - calibration curve

22. EDX detector Incident X-ray beam Reflected X-ray beam Reflector Principle of TXRF ADVANTAGES • Background reduction • Double excitation of sample by both the primary and reflected beam • Small distance sample-detector • (~1mm) large solid angle • Small sample volumes required • Detection limits in the pg range with X-ray tube excitation DISAVANTAGES • Collimated beam required • Sample preparation necessary for non liquid samples

23. Comparison between TXRF and EDXRF spectrum

24. Main Advantages of TXRF • Unique micro analytical applications for liquid and solid samples • No matrix effects • A single internal standard greatly simplifies quantitative analyses • Excellent detection limits (ppt or pg) for all elements from sodium to plutonium • Calibration and quantification independent from any sample matrix • Excellent dynamic range from ppt to percent • Simultaneous multi-element ultra-trace analysis • Possibility to analyse the sample directly without chemical pre-treatment • Several different sample types and applications • No memory effects • Minimal quantity of sample required for the measurement (5 µl) • Non destructive analysis • Low running cost

25. The TXRF equipment TX 2000 • Main components: • Double anode Mo/W X-ray tube • Multilayer monochromator • MoKa, WLa/b, Bremsstr. • TXRF and EDXRF chambers • High resolution Si(Li) detector

26. Front view

27. Back view • Minimum angular step • monochromator 0.0074° • tube shield 0.0016°

28. Alignment window • Control • multilayer • tube shield • Visualise • X-ray line counts • Total counts

29. The main features of the TX 2000 Spectrometer • Minimal distance between the sample and the detector (mounted to the axis normal plane of the sample). In this position the detector is also completely out of the primary beam, as the angle between the incident and the reflected beams is so large • TXRF and EDXRF (traditional • 45° geometry) spectroscopy in • the same equipment • Automatic switching of primary beam (MoKa W/La and Brems-strahlung 33 keV) using double anode Mo/W X-ray tube, based on innovative software. We select the energy required using a high reflectivity 80% (WLa/Lb/MoKa) multilayer. We can choose also other X-ray tubes and monochromatise the energy that you need • Instrumental detection limits for more than 50 elements below 10 pg • Helium device to improve the detection limits for the light elements • The spectrometer is fully automated and you can control different total reflection conditions for different energies from the PC, using stepping-motors moving monochromator and tube shield and MS Windows software. • 3.8 liters UHV (Si(Li) 20 mm2 detector area) high resolution detector <137 eV (Ka Mn radiation at 5.89 keV), with an ultra-thin and highly corrosion resistant window (8 mm Dura-Beryllium)

30. Multielement standard - WL K Zn K L L M Cu Ni Co W L scatter Fe Mn Tl, Pb, Bi Cr K Ca Cu Sr Cd Ba Ni Ba Ag Si Al

31. Sr K K L L L Ga M Zn Cu Tl Mo scatter Ni Pb Bi Co Pb Bi Tl Fe Mn Tl, Pb, Bi Sr Cr Ca Zn Si Pb K Ba Bi Sr Al Ba Multielement standard - MoK

32. Multielement standard – 33keV

33. Detection Limits < 5 pg 5-10 pg 10-30 pg 30-100 pg >100 pg Elemental sensitivity periodic table Excitation radiation W-L Line W-white Line Mo-K Line

34. Sample holder A droplet of 10 µL is pipetted on a carrier with a diameter of 3 cm The droplet leaves a dry residue after evaporation. isinfo@italstructures.com www.italstructures.com

35. Sample preparation scheme

36. Preparation of a TXRF measuring sample Addition of some µL internal standard Homogenization by shaking Taking off some µL Aliquotation of some mL Si(Li)-Detector Drying by evaporation Pipetting on clean carrier Measurement

37. Applications • Oils and greases: crude oil, essential oil, fuel oil • Environmental Analysis: water, dust, sediment, aerosol • Pigments: ink, oil pants, powder • Medicine: toxic elements in biological fluids and tissue samples • Semiconductor Industry • (direct or after VPD-VPT) • Forensic Science: analysis of extremely small sample quantities • Nuclear Industry: measurements of radioactive elements • Pure chemicals: acids, bases, salts, solvents, water, ultra pure reagents

38. Spectrum of detection limits Chromium in distilled water

39. Example of detection limits Chromium in distilled water

40. Choice of the anode

41. Forensic: gunshot powder counts / channel

42. Forensic: fiber analysis

43. Food industry: wine K K Mo K 40kV 30mA 500s Ga int standard Ca L L Ca Mo scatter Cu Ga Rb S Fe Cl Zn Si P Sr Pb Mn Cr Pb Rb K Zn Al

44. Industrial application case study: Petrochemical transformation Process assistance and quality control Monitor corrosion phenomena and possibly give indications on the origin (Fe, Ni, Cr, Mn) Individuate transport processes of elements deriving for catalyst (Co, Ni, Pt, Rh, Cr, Cu, …) Logistics • Search the probable causes of deterioration (contamination) of the products during Transport and Stocking – Reflects on product price and on logistic costs (e.g. ship stop)

45. Applications • Raw materials for intermediate products • Intermediate compounds for the synthesis of final products destined to high consumption markets Cosmetics Detergents Lubrication Paper Industry Plastics Food industry Leather industry The limits for the metals content are regulated by different norms, mostly dictated by Acceptance Specifications of the client.

46. 17 ppb Olefin C10-13 70 ppb Ctz.: Pt, Ni

47. 50 ppb 8 ppb Linear paraffin C10-13

48. Detection limits: ICP-OES vs. TXRF ICP-OES (ASTM: D 5708-B) Campione : 10g @ 25 ml

49. Correlation ICP-OES vs. TXRF • ICP-OES vs. TXRF • Paired t-test : results do not differ significantly • Linearly correlated

50. Conclusions