atomic absorption spectroscopy (absorption)

2. ATOMIC ABSORPTION
SPETROSCOPY
ATOMIC ABSORPTION
BY
ABDUL QAYOOM MUGHERI
M,phil scholar
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Atomic Absorption Spectroscopy
Introduction
Atomic absorption spectroscopy is an analytical
technique for determining the concentration
of a particular metal element in a sample.
This technique can be used to analyze the
concentration of over 70 different metals in a
solution.

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Background
Atomic absorption spectrometry was first used
as an analytical technique.
It was established in the second half of the
19th century.
The modern form of AAS was largely
developed during the 1950s by Sir
Alan Walsh

5. Atomic Energy Level Diagrams
we should be aware that only valence
electrons are responsible for atomic
spectra observed in a process of
absorption or emission . Valence
electrons in their ground states are
assumed to have an energy equal to
zero . As an electron is excited to a
higher energy level, it will absorb energy
exactly equal to the energy difference
between the two states.
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Atomic Emission and Absorption
Spectra
At room temperature, essentially all atoms
are in the ground state. When they
absorb energy they excited. Excited
electrons will only spend a short time in
the excited state an excited electron will
emit a photon and return to the ground
state.

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The Effect of Temperature on Atomic
Spectra
Atomic spectroscopic methods require
the conversion of atoms to the
gaseous state. This requires the use
of high temperatures (in the range
from 2000-6000 oC). The high
temperature can be provided
through a flame, electrical heating.

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The original 1954 AAS instrument
11/21/14

9. Atomic absorption spectrophotometer
consists of a light source, a sample
compartment and a detector.
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10. - Atomic absorption is a very common
technique for detecting metals and
metalloids in environmental samples.
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11. Elements detectable by atomic absorption are highlighted in pink in this periodic table
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12. Atomic Absorption Spectrometer
• Atomic absorption spectrometers have 4
principal components
1 - A light source ( usually a hollow cathode lamp )
2 – An atom cell ( atomizer )
3 - A monochromator
4 - A detector , and read out device .
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13. Schematic diagram of AAS
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14. ATOMIZATION
Elements to be analyzed needs to be in
atomic state.
Atomization is the separation of
particles into individual molecules and
breaking molecules into atoms .This is
done by exposing the analyte to high
temperature in a flame or graphite
furnace .
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15. There are two types of atomization
A. Flame B. Graphite furnace
atomization .
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16. FLAME
Flame AA can only analyze solutions ,
where
path length, and therefore to increase the
total absorbance .
 Sample solutions are usually introduced
into a nebuliser , which can be readily
broken down in the flame.
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18. TYPES OF FLAME
The common fuels and oxidants employed in flame spectroscopy and the
approximate range of temperature realized with each of these mixtures.
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19. ABSORPTION SYSTEM
The process by which the energy of the
light (in the form of photons) is transferred
to the atoms or molecules raising them
from the ground state to an excited state
,that absorbed radiations are
characteristics for each element.
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20. The Atomic Absorption Spectrometer
Sample Introduction System
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Nebuliser
Capillary
Solution

21. A mechanical device that burns a gas or liquid fuel into
a flame in a controlled manner
TYPES OF BURNER
 Premix chamber burner
 Total consumption burner
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22. PREMIX BURNER
 Most commonly use premix burner
the oxidant-sample mixture flows
into a chamber located upstream
from the flame, where the larger
drops are separated from the mixture
and discarded.
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23. Importance of Flame in
Atomization
 A Flame burning in air forms an ideal means for converting a
Solution into the atomic vapor required for atomic absorption
 A flame is simple, inexpensive & easy to use
 A flame provides a remarkably stable environment for
atomic absorption
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24. GRAPHITE FURNACE
 The graphite furnace has several advantages
over a flame. First it accept solutions or solid
samples.
 Samples are placed directly in the graphite
furnace and the furnace is electrically heated
in several steps to dry the sample, ash organic
matter, and vaporize the analyte atoms.
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25. Advantages Over AAS
 Solutions and solid samples can be analyzed.
 Much more efficient atomization
 Greater sensitivity
 Smaller quantities of sample (typically 1-
100μL)
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26. Disadvantages
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 Expensive
 low precision
 low sample
throughput
 requires high level of
operator skill

27. ACKNOWLEDGEMENT
I am thankful to Almighty Allah,
prof. Dr. Tasneem Gul kazi
And also thankful to my classmates for wonderful
cooperation.
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