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ATOMIC ABSORPTION SPECTROMETER PowerPoint Presentation
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ATOMIC ABSORPTION SPECTROMETER

ATOMIC ABSORPTION SPECTROMETER

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ATOMIC ABSORPTION SPECTROMETER

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  1. ATOMIC ABSORPTION SPECTROMETER SELİN CANSU ÖZTÜRK ŞEYMA ATAKUL SEZİN GÜNER

  2. ATOMIC ABSORPTION SPECTROMETER • Introduction • Invention • WorkingPrincipleof AAS • Instrumentation • Interferences & CorrelationMethods • Applications

  3. INVENTION • Introduced in 1955 by Alan Walsh in Australia • Firstlyusedformining, medicaltreatment&agriculture • Alan Walsh(1916-1998) http://www.science.org.au/academy/memoirs/walsh2.html

  4. PROPERTIES OF AAS • Themostwidelyusedmethod in analysis of elements • Based on theabsorption of radiation • Sosensitive (ppb) • Quantitativeanalysis

  5. WORKING PRINCIPLE OF AAS • Electronspromotetohigherorbitalsfor a shortamount of time byabsorbing a energy • M + hv →M* • Relises on Beer-Lambert Law A= a.b.c

  6. INSTRUMENTATION www.scientificlib.com

  7. LIGHT SOURCES HollowCathodeLamps • Anot-Tungsten wire • Cathodemadefromthe element of interest (Na,K,Ca..) • Argon or neon gas http://www.safir.be/AAS.ht

  8. LIGHT SOURCES ElectrodelessDischargeLamp • Typically argon gas at lowpressure • Narrowerlinewidth • Not prefered www.freepatentsonline.com

  9. ATOMIZATION • Compoundsmakingupthesamplearebrokenintofreeatoms. • High temperature is necessary • Basic twotypes -Flameatomizer -Electrothermalatomizer

  10. TYPES OF ATOMIZERS FLAME ATOMIZER • Simplestatomization • Convertsanalyteintofreeatoms of vaporphase • Flammable &causticgases • Not has an inertmedium(−) • Shortanalysis time (−)

  11. TYPES OF ATOMIZERS ELECTROTHERMAL ATOMIZER • A cylindiricalgraphitetube • Inertgasmedium (Argon gas) • Longeranlaysis time thanflame • Superiorsensitivity, highaccuracy

  12. MONOCHROMATOR • Alsoit is calledwavelenghselector • Select thespecificwavelenght • Polychromaticlight →monochromaticlight • Simple one is enoughfor AAS

  13. DETECTOR • Electromagneticwaves→ electriccurrent • ThemostusedonePhotomultipliertube • Havefastresponsetimes www.answers.com

  14. CALIBRATION TECHNIQUES • Two main techniques • Calibrationcurvemethod • Standart additionmethod

  15. CALIBRATION TECHNIQUES CALIBRATION CURVE METHOD • Draw a graph • Havetwoormorevariables -One is set at knownvalues -One is measuredresponse • Most convenient fora large number of similar samplesanalysis.

  16. CALIBRATION TECHNIQUES An example of calibrationcurvemethod

  17. CALIBRATIONTECHNIQUES STANDART ADDITION METHOD • To measure the analyte concentration in a complexmatrix. • Most convenient for small number of samplesanalysis • Preventeffect of chemical & spectralinterferences

  18. INTERFERENCES • Causes higherorlowerabsorbancevalue • Twomajorgroups • ChemicalInterferences • SpectralInterferences

  19. CHEMICAL INTERFERENCES • Themostcommonone in flameatomizer. • Consequence of chemicalreactions. • Reduceamount of oxygen in flametoovercome

  20. SPECTRAL INTERFERENCES • Absorptionoremission of theradiation at thesamewavelength • Radiationwhich is absorbed→pozitiveerrors • Radiationwhich is emmitted→negativeerrors

  21. SPECTRAL CORRELATION METHODS TWO-LINE CORRELATION METHOD • Select twoline • characteristicwavelength of analyte • veryclosetoanalyteline but not absorbedbyanalyte • Measurethedifferencebetweentwolines

  22. SPECTRAL CORRELATION METHODS CONTINUUM SOURCE CORRELATION METHOD • Select twolamps • Deuteriumlamp & hollowcathodelamp • Whenhollowcathodelamp is used total absorbace is measured • Whendeuteriumlamp is usedonly background absorption is measured • Measurethedifferencebetweentwolines.

  23. SPECTRAL CORRELATION METHODS ZEEMAN EFFECT CORRELATION METHOD • Presence of magneticfield. • Splitting of spectrallines.

  24. CONCLUSION • One of themostimportanttechnique in quantitativeanalysis • It is based on theabsorption of radiation • Measurementscould be done at ppblevels • It’swidelyusedmethod • Thepreparation of thesample is usuallysimpleandrapid

  25. CONCLUSION • Therearemanyadventages • High sensitivity [10-10 g (flame), 10-14 g (non-flame)] • Goodaccuracy (Relativeerror 0.1 ~ 0.5 % ) • Highselectivity

  26. APPLICATIONS OF AAS • Water analysis (e.g. Ca, Mg, Fe, Si, Al, Ba content) • Foodanalysis • Analysis of animal feedstuffs (e.g. Mn, Fe, Cu, Cr, Se,Zn) • Analysis of soils • Clinicalanalysis (bloodsamples: wholeblood, plasma,serum; Ca, Mg, Li, Na, K, Fe)

  27. REFERENCES • http://www.scribd.com/doc/10513921/Atomic-Absorption-Determination-of-Zinc-and-Copper-in-a-Multivitamin • http://www.hemlin.pp.se/USstarten.html • http://www.learn-english-today.com/business-english/presentations-phrases.htm

  28. THANKS FOR YOUR ATTENTION..