AAS – Atomic Absorption Spektrometry

Klímová Eva Maarová Darja Brno University of Technology 2005

Fundamentals   Analytic method that measures the concentrations of elements Most of the free atoms of most of elements are in the basic energy condition at temperatures 2000-3150 K and because of absorption of the photons they are getting to some of the higher energy levels.

 In ASS they have the most probability to get to the junctions between basic and nearest energy excited state. These junctions match to basic resonance curve, which are the most sensitive for atoms.

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

A

 log   0

Data evaluation  Calibration curve method

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

Device Different types of Atomic absorption spectrometers

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

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

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

Types of atomisation   Electrothermal atomisation (grafit cuvettes) Higher temperature is reached here (3150K)

Monochromator   Optical grid Is used to select the specific wavelenght of light – spectral line

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

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

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

Thank you for your attention!

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