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Atomic Absorption Spectroscopy

Atomic Absorption Spectroscopy

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Atomic Absorption Spectroscopy

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  1. Atomic Absorption Spectroscopy | | 1

  2. Content 3.1. Theoretical Concepts 3.2. Atomic Absorption Instrumentation 3.3. Graphite Furnace Atomic Absorption 3.4. Control of Analytical Interferences | | 2

  3. 3.1. Theoretical Concepts • The Atomic Absorption Process • Theoretical Concepts • Quantitative Analysis • Characteristic Concentration • Detection Limits | | 3

  4. The Atomic Absorption Process | | 4

  5. Fig3-2 Grotrian diagrams for K Fig 3-3Grotrian diagrams for Na | | 5

  6. | | 6

  7. 2. Theoretical Concepts⑴Integral Formula of AASFig 3-4 Typical Shape of A Atomic Absorption line | | 7

  8. Integral Absorption FormulaBy atomic theory (3.1) By Line Shape Function ( the Nature distribute ) (3.2) The Peak Absorption Coefficient k0 is: (3.3) | | 8

  9. ⑵ Peak Absorption Theoryby Lambert-Beer’s Law: (3.4) (3.5) (3.6) | | 9

  10. The Absorbance is: (3.7) | | 10

  11. When: va>> ve, and v0a= v0e, then kv≈k0, | | 11

  12. (3.8) | | 12

  13. (3.9) (3.10) | | 13

  14. 3. Quantitative Analysis (3.10) | | 14

  15. 4. Characteristic Concentration (3.11) | | 15

  16. 5. Detection Limit (3.12) | | 16

  17. | | 17

  18. 3.2. Atomic Absorption Instrumentation | | 18

  19. 1. Photometers for AAS | | 19

  20. 1. Photometers for AAS | | 20

  21. A New Type Photometer for AAS | | 21

  22. 2. line source (Hollow Cathode Lamp ) Fig 3-13 | | 22

  23. Hollow Cathode Lamp Emission Process Fig 3-14 | | 23

  24. 3. Atomizer for AAS (Pre-Mix Burner System) | | 24

  25. | | 25

  26. Fig 4-19 Tree Type Burner Head for different Type Flame | | 26

  27. | | 27

  28. 4. Control of Analytical Interferences Ionization interference Matrix interference Chemical interference Background interference | | 28

  29. Ionization Interference Ba → Ba+ + e- K → K+ + e- | | 29

  30. Matrix Interference | | 30

  31. Chemical Interference | | 31

  32. The Method Of Standard Additions | | 32

  33. | | 33

  34. Background Interference | | 34

  35. | | 35

  36. (4.13) AHCL= Aa+ Ab (4.14) AD2=Ab, (4.15) Aa = AHCL- AD2 | | 36

  37. 3.3. Graphite Furnace Atomic Absorption • Graphite furnace atomizer components • The Graphite Furnace Power Supply and Programmer • Quantitative analysis GFAAS • Effect of Matrix on Height and Area | | 37

  38. 1. Graphite furnace atomizer components The Graphite Furnace Atomizer A basic graphite furnace atomizer is comprised of the following components: · graphite tube · electrical contacts · enclosed water cooled housing · inert purge gas controls | | 38

  39. THGA graphite tube Fig 4-27 | | 39

  40. The Graphite Furnace Power Supply and Programmer • A Graphite Furnace Temperature Program • Drying • Pyrolysis • Cool Down(optional) • Atomization • Clean Out • Cool Down | | 40

  41. | | 41

  42. | | 42

  43. | | 43

  44. | | 44