ICP-AES (ICP-OES)

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ICP-AES (ICP-OES)

• Inductively coupled plasmas are at least 2X as
  hot as flames or furnaces.
• The Ar plasma is the result of the flow of Ar
  ions in a very strong, localized radio field.
• 6000-10000 K are common.
• Hot enough to excite most elements so they emit
  light.
• Hot enough to prevent the formation of most
  interferences, break down oxides and eliminate
  most molecular spectral interferences.
• The way to do atomic emission spectroscopy today.

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• How does ICP work?
• Radio frequency electrical current and associated
  magnetic field
• Ionization of Ar gas (sparked by a Tesla coil)
• Acceleration of ions and electrons by magnetic
  field
• Energy in transferred from the electrons to the
  gas by collision so the gas is heats up.
• Production of high concentartion of both EXCITED
  ATOMS and ions

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Plasmas gas or
Three gases
Support gas or auxiliary gas
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How to measure temperature?

• The plasma is thermodynamic equilibrium
• Cannot characterize a single temperature
• Four temperatures can be used
• Excitation Temp (Texc) measure of population
  density of the energy levels (Boltzman
  equilibrium)
• Ionization Temp (Tion) measure of population
  density of different ionization states (Saha
  equilibrium)
• Electron Temp (Te) a measure of the kinetic
  energy of the electrons (related to the velocity
  of free electrons)
• Gas Temp (Tg or T kinetic) a measure of the
  kinetic energy of the atoms.
• Tg lt Texc lt Tion lt Te
• N1/N0 g1/go exp(?E/kT)

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Hydride generation
3BH4- 3H 4H3AsO3 ?3H3BO3 4AsH3 3H20
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Performance characteristics

• Elements determined
• 60 elements
• Line selection
• Most elements have several lines that can be
  selected
• Linear range
• Better than AAS
• Interferences
• Chemical interferences (lowered)
• Spectral interferences (still a problem)
• Detection limits
• Comparable or better than other atomic spectral
  techniques

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