ATOMIC
ABSORPTION
SPECTROSCOPY
Benny Alexander 1606831585
Jordan Andrean M 1606871032
Riski Winner L 1606836755
ATOMIC ABSORPTION
SPECTROSCOPY
• Working Principle of AAS
• Instrumentation
• Interferences & Correlation Methods
• Applications
PROPERTIES OF AAS
• The most widely used method in analysis of elements
• Based on the absorption of radiation
• So sensitive (ppb)
• Quantitative analysis
WORKING PRINCIPLE
OF AAS
• Electrons promote to higher orbitals for a short amount
of time by absorbing a energy
• M + hv → M*
• Relises on Beer-Lambert Law
A= a.b.c
INSTRUMENTATION
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LIGHT SOURCES
Hollow Cathode Lamps
• Anot-Tungsten wire
• Cathode made from the element of interest (Na,K,Ca..)
• Argon or neon gas
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LIGHT SOURCES
Electrodeless Discharge Lamp
• Typically argon gas at low pressure
• Narrower line width
• Not prefered
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ATOMIZATION
• Compounds making up the sample are broken into
free atoms.
• High temperature is necessary
• Basic two types :
Flame atomizer
Electrothermal atomizer
TYPES OF ATOMIZERS
FLAME ATOMIZER
• Simplest atomization
• Converts analyte into free atoms of vapor phase
• Flammable &caustic gases
• Not has an inert medium (−)
• Short analysis time (−)
TYPES OF ATOMIZERS
ELECTROTHERMAL ATOMIZER
• A cylindirical graphite tube
• Inert gas medium (Argon gas)
• Longer anlaysis time than flame
• Superior sensitivity, high accuracy
MONOCHROMATOR
• Also it is called wavelengh selector
• Select the specific wavelenght
• Polychromatic light →monochromatic light
• Simple one is enough for AAS
DETECTOR
• Electromagnetic waves → electric current
• The most used one Photomultiplier tube
• Have fast response times
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CALIBRATION
TECHNIQUES
• Two main techniques :
Calibration curve method
Standart addition method
CALIBRATION
TECHNIQUES
CALIBRATION CURVE METHOD
• Draw a graph
• Have two or more variables
-One is set at known values
-One is measured response
• Most convenient for a large number of similar samples
analysis.
CALIBRATION
TECHNIQUES
An example of calibration curve method
CALIBRATION
TECHNIQUES
STANDART ADDITION METHOD
• To measure the analyte concentration in a complex
matrix.
• Most convenient for small number of samples analysis
• Prevent effect of chemical & spectral interferences
INTERFERENCES
• Causes higher or lower absorbance value
• Two major groups :
Chemical Interferences
Spectral Interferences
CHEMICAL
INTERFERENCES
• The most common one in flame atomizer.
• Consequence of chemical reactions.
• Reduce amount of oxygen in flame to overcome
SPECTRAL
INTERFERENCES
• Absorption or emission of the radiation at the same
wavelength
• Radiation which is absorbed→positive errors
• Radiation which is emmitted→negative errors
SPECTRAL
CORRELATION
METHODS
TWO-LINE CORRELATION METHOD
• Select two line
characteristic wavelength of analyte
very close to analyte line but not absorbed by analyte
• Measure the difference between two lines
SPECTRAL
CORRELATION
METHODS
CONTINUUM SOURCE CORRELATION METHOD
• Select two lamps
Deuterium lamp & hollow cathode lamp
• When hollow cathode lamp is used total
absorbace is measured
• When deuterium lamp is used only background
absorption is measured
• Measure the difference between two lines.
SPECTRAL
CORRELATION
METHODS
ZEEMAN EFFECT CORRELATION METHOD
• Presence of magnetic field.
• Splitting of spectral lines.
CONCLUSION
• One of the most important technique in quantitative
analysis
• It is based on the absorption of radiation
• Measurements could be done at ppb levels
• It’s widely used method
• The preparation of the sample is usually simple and
rapid
CONCLUSION
• There are many adventages
High sensitivity
[10-10 g (flame), 10-14 g (non-flame)]
Good accuracy
(Relative error 0.1 ~ 0.5 % )
High selectivity
APPLICATIONS OF AAS
• Water analysis (e.g. Ca, Mg, Fe, Si, Al, Ba content)
• Food analysis
• Analysis of animal feedstuffs (e.g. Mn, Fe, Cu, Cr, Se,Zn)
• Analysis of soils
• Clinical analysis (blood samples: whole blood,
plasma,serum; Ca, Mg, Li, Na, K, Fe)
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
THANK YOU
