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IN THE NAME OF GOD

IN THE NAME OF GOD. INSTRUMENTAL ANALYSIS. Classification of Analytical Methods:. 1- Classical or Chemical Methods 2- Instrumental Methods. Classical Methods:. Separating the Components of sample by precipitation, Extraction or Distillation

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IN THE NAME OF GOD

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  1. IN THE NAME OF GOD

  2. INSTRUMENTAL ANALYSIS

  3. Classification of Analytical Methods: 1- Classical or Chemical Methods 2- Instrumental Methods

  4. Classical Methods: • Separating the Components of sample by precipitation, Extraction or Distillation • Qualitative Analysis by treating the separated components with reagents that yield products that can be recognized by their colors, their solubilities in a series of solvents, their melting or boiling points, their oders, their optical activities or their refractive indexes. • Quantitative Analysis by Gravimetric or Titrimetric measurements.

  5. Instrumental Methods: Early in the 20th century, measurements of Physical properties of analyts such as conductivity, electrode potential, light absorption or emission, mass to charge ratio, fluorescence,… began to be used for quantitative and qualitative analysis of a variety of inorganic, organic and biochemical analytes.

  6. Emission of radiation Absorption of radiation Scattering of radiation Refraction of radiation Diffraction of the radiation Rotation of the radiation Electrical potential Electrical current Electrical resistance Mass Mass to charge ratio Rate of reaction Thermal charact. radioactivity Types of Instrumental Methods:

  7. Atomic Spectrometric Methods for Qualitative and Quantitative determinations: 1- optical Spectrometry 2- Mass Spectrometry 3- X – Ray Spectrometry

  8. Atomic Spectroscopy Based on Ultraviolet and Visible Radiation: • Qualitative and Quantitative determination of more than 70 elements. • Sensitivities of Atomic methods lie in the ppm, ppb and ppt range. • Fast, High selective and moderate instrument costs.

  9. Atomic Spectrum of Hg

  10. Molecular Spectrum:

  11. Energy Level Diagram:

  12. ATOMIC LINE WIDTHS • Atomic line widths are caused by: • Doppler broadening • Pressure effects due to collisions

  13. Doppler broadening : No shift is seen for atoms perpendicular to the path of the photon detector. Atoms moving toward the photon detector are detected at a higher frequencies and those moving away from the detector at a lower frequencies.

  14. Pressure broadening: Pressure or collisional broadening results from the collisions of the emitting or absorbing species with other atoms or ions in the heated medium. These collisions cause small changes in the ground and Excited state energy levels and lead to a range of absorbed And emitted wavelengths.

  15. Optical ATOMIC SPECTROSCOPY: 1- Atomic Absorption Spectroscopy (AAS) 2- Atomic Emission Spectroscopy (AES) 3- Atomic Fluorescence Spectroscopy (AFS)

  16. Atomic Absorption Spectroscopy: A= ε b C Bear-Lambert Law

  17. Types of Atomic Absorption Spectroscopy: 1- Flame Atomic Absorption Spectreoscopy (FAAS) 2- Electrothermal ( Flame-less ) Atomic Absorption Spectroscopy (EAAS)

  18. Flame Atomic absorption spectrometer

  19. In this method, light from a source is directed through the sample to a detector. Light Path

  20. Sources for AAS: 1- Hollow Cathode Lamps (HCL) Multielement lamps are available. 2- Electrodeless Discharge Lamps (EDL)

  21. Hollow cathode lamp: The source of light is a lamp whose cathode is composed of the element being measured. Each element requires a different lamp.

  22. The lamp is housed inside the lamp compartment of the instrument.

  23. atomic line source (HCL)

  24. Sample Introduction Methods: 1- Introduction of solution samples: • Pneumatic Nebulizers • Electrothermal (furnace) evaporator • Hydride generation (As, Sb, Sn, Se, Bi, Pb ) • Cold vapor atomization ( Hg )

  25. a )Pneumatic Nebulizers 1- Concentric tube 2- Cross flow 3- Fritted disk 4- Babington

  26. Pneumatic Nebulizers :

  27. Concentric Nebulizer

  28. Flame pneumatic nebulizer Adjustment of position of inner capillary Typical uptake rate: ~5 mL/min Typical delivery efficiency: ~5% http://www.chemistry.nmsu.edu/Instrumentation

  29. Electrothermal evaporator : There is no nebulziation, etc. The sample is introduced as a drop (usually 10-50 uL) The furnace goes through several steps: a- Drying (usually just above 110 deg. C.) b- Ashing (up to 1000 deg. C) c- Atomization (Up to 2000-3000 C) d- Cleanout (quick ramp up to 3500 C or so). Waste is blown out with a blast of Ar.

  30. Electrothermal atomic absorption (Graphite furnace) Temp Absorbance signal time Introduced sample (solid, liquid, gas, slurry) Pulse heat the ETV

  31. A hydride generation and atomization system

  32. 2- Introduction of solid samples: • Electrothermal evaporators • Arc or spark ablation • Laser ablation • Glow discharge technique

  33. Glow discharge atomization:

  34. Free atom formation(Atomization) We need to be able to convert our sample to the atoms. Desolvation Volatilization Dissociation and ionization

  35. SAMPLE INTRODUCTION AND ATOMIZATION

  36. Sample atomization techniques: 1-Flame atomization 2-Electrothermal atomization 3- Glow discharge atomization 4- Hydride atomization 5- Cold – vapor atomization

  37. Nebulizer / Burner system

  38. Advantages of flame: Convenient Reproducible Easy to use inexpensive

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