Its all about absorption & emission of radiation by specific element present in the sample. We can calculate Absorption in terms of Transmittence by Beer's Lambert law. A= 2-log(%T) or A= log(transmittance)

1. ATOMIC ABSORPTION
SPECTROMETER
BCH-503

2. ATOMIC ABSORPTION
SPECTROMETER
• Introduction
• Invention
• Working Principle of AAS
• Instrumentation
• Interferences & Correlation Methods
• Applications

3. INTRODUCTION
• Atomic absorption spectroscopy (AAS) is a
spectroanalytical procedure for the quantitative
determination of chemical elements using the
absorption of optical radiation (light) by free
atoms in the gaseous state.
• In analytical chemistry the technique is used
for determining the concentration of a
particular element (the analyte) in a sample to
be analyze

4. INVENTION
• Introduced in 1955 by Alan Walsh in Australia
• Firstly used for mining, medical
treatment&agriculture
• Alan Walsh(1916-1998)
• At the Commonwealth Scientific
and Industrial Research
Organisation (CSIRO)
• Solid & Solutions

5. Atomic absorption spectroscopy is based on the same
principle as the flame test used in qualitative analysis.

6.  The high temperature of the flame excites a
valence electron to a higher-energy orbital.
 The atom then emits energy in the form of light as
the electron falls back into the lower energy orbital
(ground state).
The intensity of the absorbed light is
proportional to the concentration of the element
in the flame.

7.  quantitative analysis
Atomic Spectra

9. PROPERTIES OF AAS
• The most widely used method in analysis of
elements
• Based on the absorption of radiation
• So sensitive (ppb)
• Quantitative analysis

10. 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

11. Each element has a characteristic spectrum.
Example: Na gives a characteristic line at 589 nm.
Atomic spectra feature sharp bands.
There is little overlap between the spectral lines of different
elements.

12. Atomic absorption spectroscopy and atomic emission
spectroscopy are used to determine the concentration of an
element in solution.

13. INSTRUMENTATION

14. LIGHT SOURCES
Hollow Cathode Lamps
• Anot-Tungsten wire
• Cathode made from the element of interest
(Na,K,Ca..)
• Argon or neon gas

15. LIGHT SOURCES
Electrodeless Discharge Lamp
• Typically argon gas at low pressure
• Narrower line width
• Not prefered
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16. ATOMIZATION
• Compounds making up the sample are broken
into free atoms.
• High temperature is necessary
• Basic two types
-Flame atomizer (air-acetylene flame)
-Electrothermal atomizer

17. Process in a Flame AA
M* M+ + e_
Mo M*
MA Mo + Ao
Solid Solution
Ionization
Excitation
Atomization
Vaporization

18. TYPES OF ATOMIZERS
FLAME ATOMIZER
• Simplest atomization
• Converts analyte into free atoms of vapor
phase (Pnumatic Nabulizer+Aerosol)
• Flammable & caustic gases
• Not has an inert medium (−)
• Short analysis time (−)

20. TYPES OF ATOMIZERS
ELECTROTHERMAL ATOMIZER
• A cylindirical graphite tube atomizer
• 20–25 mm in length and 5–6 mm inner diameter
• Developed at St.Petersburg Russia
• Liquid(typically 10–50 μL) or a solid (1 mg)
– Drying – solvent is evaporated;
– Pyrolysis – matrix constituents are removed
– Atomization – analyte element is released to the gaseous phase
– Cleaning –high temperature.
• Tubes may be heated transversely or longitudinally
• Resistivity is noted

22. MONOCHROMATOR
– Also it is called wavelengh selector
– Select the specific wavelenght
– Polychromatic light →monochromatic light
– Simple one is enough for AAS

23. DETECTOR
• Electromagnetic waves → electric current
• The most used one Photomultiplier tube
• Have fast response times

24. CALIBRATION TECHNIQUES
• Two main techniques
1. Calibration curve method
2. Standart addition method

25. 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.

26. CALIBRATION TECHNIQUES
An example of calibration curve method
Y=bx+a

27. 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

28. INTERFERENCES
• Causes higher or lower absorbance value
• Two major groups
Chemical Interferences
Spectral Interferences

29. CHEMICAL INTERFERENCES
• The most common one in flame atomizer.
• Consequence of chemical reactions.
• Reduce amount of oxygen in flame to
overcome

30. SPECTRAL INTERFERENCES
• Absorption or emission of the radiation at the
same wavelength
• Radiation which is absorbed→pozitive errors
• Radiation which is emmitted→negative errors

31. Atomic Absorption Overview

32. 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

33. 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

34. 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)