Name : Shreya .V. Dhokai
M.Sc.
Biochemistry Sem: 1
ATOMIC ABSORPTION
SPECTROMETER
 Introduction
 Invention
 Working Principle of AAS
 Instrumentation
 Interferences
 Applications
INVENTION
 Introduced in 1955 by Alan Walsh in Australia
 Firstly used for mining, medical treatment&agriculture
 Alan Walsh(1916-1998)
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
LIGHT SOURCES
Hollow Cathode Lamps
 Anode-Tungsten wire
 Cathode made from the element of interest (Na,K,Ca..)
 Argon or neon gas
LIGHT SOURCES
Electrodeless Discharge Lamp
 Typically argon gas at low pressure
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
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
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
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 advantages
 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-aMultivitamin
 http://www.hemlin.pp.se/USstarten.html
 http://www.learn-english-today.com/businessenglish/presentations-phrases.htm
THANK YOU