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AAS – Atomic Absorption Spektrometry

AAS – Atomic Absorption Spektrometry. Klímová Eva Maarová Darja Brno University of Technology 2005. Fundamentals. Analytic method that measures the concentrations of elements

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AAS – Atomic Absorption Spektrometry

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  1. AAS – Atomic Absorption Spektrometry Klímová Eva Maarová Darja Brno University of Technology 2005

  2. Fundamentals • Analytic method that measures the concentrations of elements • Most of the free atoms of most of elements are in the basicenergy condition at temperatures2000-3150 K and because of absorption of the photons theyare getting to some of the higher energy levels. • In ASS they have the most probability to get tothe junctions between basic and nearest energyexcited state. These junctions match to basicresonance curve, which are the most sensitive for atoms.

  3. Comparative methode, absorbance value • is measured • For AAS applies Bouger-Lambert-Beers Law:

  4. Data evaluation • Calibration curve method

  5. Instrumentation • Atomic absorption spectrometer,that contains 4 basic parts: • The light source • Atomic cell • Monochromator • Detector

  6. Device Different types of Atomic absorption spectrometers

  7. The light source • Provides radiation • Hollow cathode lamp • Is made of the element to be determined • Filled with an inert gas (Ar,He)

  8. The atomic cell • Is instrumental to the atomisation • Sample is changed to form free atoms in gas state (generation of free atoms of elements)

  9. Types of atomisation • Flame atomisation (slotted burners) • Temperature of flame is directed according to Oxidant-fuel ratio (ethyne-air,ethyne-dinitrogenoxide are often used)

  10. Types of atomisation • Electrothermal atomisation (grafit cuvettes) • Higher temperature is reached here (3150K)

  11. Monochromator • Optical grid • Is used to select the specific wavelenght of light – spectral line

  12. Detector • Works on principle of the photoefect • A photomultiplier tube • Produces an elecrical signal proportional to the light intensity

  13. Applications • Clinical analysis – analysing metals in biological fluids such as blood and urine • Environmental analysis – monitoring our environment (levels of various elements in water,air, petrol etc.) • Pharmaceuticals • Industry • Mining – determining gold in rocks

  14. Wordlist • Mining – důlní průmysl, těžba • Comparative method – srovnávací metoda • Atomic cell – atomizátor • Ratio – poměr • Optical grid – optická mřížka • Photomultiplier tube - fotonásobič

  15. Thank you for your attention!

  16. References • Pěnčíková,H., 1998,Instrumentální analytické metody • http://webak.upce.cz/spa/metody-aas.htm • http://www.chemsoc.org/pdf/LearnNet/rsc/AA_txt.pdf • http://ewr.cee.vt.edu/environmental/teach/smprimer/aa/aa.html • http://www.google.com

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