AAS – Atomic AAS – Atomic Absorption Absorption

SpektrometrySpektrometry

Klímová EvaKlímová Eva

Maarová DarjaMaarová Darja

Brno University of TechnologyBrno University of Technology

20052005

FundamentalsFundamentals Analytic method that measures the Analytic method that measures the

concentrations of elements concentrations of elements Most of the free atoms of most of Most of the free atoms of most of

elements are in the basicelements are in the basicenergy condition at temperaturesenergy condition at temperatures2000-3150 K and because of absorption of the 2000-3150 K and because of absorption of the photons theyphotons theyare getting to some of the higher energy levels.are getting to some of the higher energy levels.

In ASS they have the most probability to get toIn ASS they have the most probability to get tothe junctions between basic and nearest energythe junctions between basic and nearest energyexcited state. These junctions match to basicexcited state. These junctions match to basicresonance curve, which are the most sensitive for resonance curve, which are the most sensitive for atoms.atoms.

Comparative methode, absorbance valueComparative methode, absorbance value is measuredis measured For AAS applies Bouger-Lambert-Beers For AAS applies Bouger-Lambert-Beers

Law:Law:

0logA

Data evaluationData evaluation

Calibration curve methodCalibration curve method

InstrumentationInstrumentation Atomic absorption spectrometer,that contains 4 Atomic absorption spectrometer,that contains 4

basic parts:basic parts: The light sourceThe light source Atomic cellAtomic cell MonochromatorMonochromator DetectorDetector

Device Device

Different types of Atomic absorption Different types of Atomic absorption spectrometersspectrometers

The light sourceThe light source

Provides radiationProvides radiation Hollow cathode lampHollow cathode lamp Is made of the element to be determinedIs made of the element to be determined Filled with an inert gas (Ar,He)Filled with an inert gas (Ar,He)

The atomic cellThe atomic cell

Is instrumental to the atomisationIs instrumental to the atomisation Sample is changed to form free Sample is changed to form free

atoms in gas state (generation of atoms in gas state (generation of free atoms of elements)free atoms of elements)

Types of atomisationTypes of atomisation

Flame atomisation (slotted burners)Flame atomisation (slotted burners) Temperature of flame is directed Temperature of flame is directed

according to Oxidant-fuel ratio (ethyne-according to Oxidant-fuel ratio (ethyne-air,ethyne-dinitrogenoxide are often used)air,ethyne-dinitrogenoxide are often used)

Types of atomisationTypes of atomisation

Electrothermal atomisation (grafit Electrothermal atomisation (grafit cuvettes)cuvettes)

Higher temperature is reached here Higher temperature is reached here (3150K)(3150K)

MonochromatorMonochromator

Optical gridOptical grid Is used to select the specific wavelenght of Is used to select the specific wavelenght of

light – spectral linelight – spectral line

DetectorDetector

Works on principle of the photoefectWorks on principle of the photoefect A photomultiplier tubeA photomultiplier tube Produces an elecrical signal proportional Produces an elecrical signal proportional

to the light intensityto the light intensity

ApplicationsApplications

Clinical analysis – analysing metals in Clinical analysis – analysing metals in biological fluids such as blood and biological fluids such as blood and urineurine

Environmental analysis – monitoring Environmental analysis – monitoring our environment (levels of various our environment (levels of various elements in water,air, petrol etc.)elements in water,air, petrol etc.)

PharmaceuticalsPharmaceuticals IndustryIndustry Mining – determining gold in rocksMining – determining gold in rocks

WordlistWordlist

Mining – důlní průmysl, těžbaMining – důlní průmysl, těžba Comparative method – srovnávací Comparative method – srovnávací

metodametoda Atomic cell – atomizátorAtomic cell – atomizátor Ratio – poměrRatio – poměr Optical grid – optická mřížkaOptical grid – optická mřížka Photomultiplier tube - fotonásobičPhotomultiplier tube - fotonásobič

Thank you for your Thank you for your attention!attention!

ReferencesReferences

Pěnčíková,H., 1998,Instrumentální Pěnčíková,H., 1998,Instrumentální analytické metodyanalytické metody

http://webak.upce.cz/spa/metody-aashttp://webak.upce.cz/spa/metody-aas.htm.htm

http://www.chemsoc.org/pdf/http://www.chemsoc.org/pdf/LearnNet/rsc/AA_txt.pdf LearnNet/rsc/AA_txt.pdf

http://ewr.cee.vt.edu/environmental/thttp://ewr.cee.vt.edu/environmental/teach/smprimer/aa/aa.htmleach/smprimer/aa/aa.html

http://www.google.comhttp://www.google.com