Atomic Absorption Spectroscopy (AAS) is a technique for detecting metals and metalloids by measuring the absorption of light at specific frequencies by free atoms in a gaseous state. The process involves the use of a hollow cathode lamp, nebulizer, atomizer, monochromator, and detector to analyze concentrations of over 62 elements in various samples. AAS is applied in fields such as clinical analysis, environmental monitoring, pharmaceuticals, industry, and mining.

1. ATOMIC
ABSORPTION
SPECTOGRAPHY

2. Hello!
I am
Keerthanaram
Faculty of Applied Science,
Vavuniya Campus, University of Jaffna
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3. “The technique uses basically
the principle that free atoms
(gas) generated in an atomizer
can absorb radiation
at specific frequency.
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Basic
Principle

4. Introduction
 Atomic Absorption Spectroscopy (AAS)
is a very common technique for
detecting metals and metalloids in
samples.
 It is very reliable and simple to use.
 It can analyze over 62 elements.
 It also measures the concentration of
metals in the sample
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5. Elements detected by AAS
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Element
s can’t
detected
by the
AAS is
shaded

6. Basic concept of AAS
Detector Nebulizer
Hollow
Cathode
Lamp
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Mono-
chromator
Atomizer
ATOMIC
ABSORPTION
SPECTROMETER

7. 01. Hollow Cathode Lamp (HCL) :
A hollow-cathode lamp
(HCL) is type of cold cathode
lamp used in physics and
chemistry as a spectral line
source
An HCL takes advantage of
the hollow cathode effect,
which causes conduction at
a lower voltage and with
more current than a cold
cathode lamp that does not
have a hollow cathode.
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Figure : Basic Diagram of a HCL
Figure : Actual photograph of a HCL

8. 02. Nebulizer
 Suck up liquid samples at
controlled rate
 Create a fine aersol spray for
introduction into flame
 Mix the aerosol and fuel and
oxidant thorughly for introduction
into flame
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9.  Elements to be analyzed needs to be
in atomic state.
 Atomization is separation of
particles into individual molecules
and breaking molecules into atoms.
 It is done by exposing the analyte to
high temperatures in a flame or
graphite furnace.
03. Atomizer
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10. 3.1 Types of Atomizer
Flame Atomizer
 To create flame, we need to mix an
oxidant gas and a fuel gas
 in most of the cases air-acetylene
flame or nitrous acetylene flame is
used
 liquid or dissolved samples are
typically used with flame atomizer
Graphite Tube Atomizer
 uses a graphite coated furnace to
vaporize the sample
 Samples are deposited in a small
graphite coated tube which can then
be heated to vaporize and atomize
the analyte
 The graphite tubes are heated using
a high current power supply
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11. 4.0 Monochromator
 This is used to separate out all of the thousands of lines.
 It will select a specific wavelength of light which is
absorbed by the sample, and to exclude other
wavelengths.
 The selection of the specific light allows the determination
of the selected element in the presence of others.
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12.  It is a detector that is typically a photomultiplier,
tube, whose function is to convert the light signal
into an electrical signal proportional to the light
intensity.
 The processing of electrical signal is fulfilled by a
signal amplifier. The signal could be displayed for
readout, or further fed onto a data station for
printout by the requested format.
05. Detector
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13. HOW IT WORKS ?
 It use the absorption of light to measure the
concentration of gas phase atoms.
 The light that is focused into the flame is produced
by a hollow cathode lamp, inside which is the
sample and an anode.
 A high voltage is passed between the cathode and
anode and the metal atoms are excited into
producing light with a certain emission spectrum.
 The photon forms an atomic spectral line when an
electron got transits from one energy level to
another.
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14.  E = hv, where
h - Planck’s constant
v- velocity of electron
E – Energy released
 The atomic radiation
produced can be
characterized by both
emission and an absorption
coefficients.
 As the quantity of energy
put into the flame is
known and the quantity
emitted can be detected, it
is possible to calculate the
concentration of the
element present.
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15. Process of formation of atomic gas
Evaporation of the liquid
to leave a dry sample
Vaporizing the
solid sample to
a gas
Atomization to
break down the
compounds
present into free
atoms.
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16. Calibration of AAS
 A calibration curve is used to
determine the unknown
concentration of an element
in a solution.
 The absorbance of each
known solution is measured
and then a calibration curve
of is of concentration vs
absorbance is plotted.
 The sample solution is fed
into the instrument, and the
absorbance of the element in
this solution is measured.
 The unknown concentration
of the element is then
calculated from the
calibration curve16

17. Applications
 Clinical analysis : Analyzing metals in biological fluids such as blood and
urine.
 Environmental analysis : Monitoring our environment – eg finding out
the levels of various elements in rivers, seawater, drinking water, air, petrol
and drinks such as wine, beer and fruit drinks.
 Pharmaceuticals : In some pharmaceutical manufacturing processes,
minute quantities of a catalyst used in the process (usually a metal) are
sometimes present in the final product. By using AAS the amount of
catalyst present can be determined.
 Industry : Many raw materials are examined and AAS is widely used to
check that the major elements are present and that toxic impurities are
lower than specified – eg in concrete, where calcium is a major constituent,
the lead level should be low because it is toxic.
 Mining : By using AAS the amount of metals such as gold in rocks can be
determined to see whether it is worth mining the rocks to extract the gold.
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18. Let’s review some concepts of AAS
Hollow Cathode Lamp
conduction at a lower voltage and with
more current
Nebulizer
Mix the aerosol and fuel and
oxidant thorughly for
introduction into flame.
Atomizer
Atomization is separation of
particles into individual
molecules and breaking
molecules into atoms.
Monochromator
It will select a specific
wavelength of light which is
absorbed by the sample, and to
exclude other wavelengths.
Detector
to convert the light signal into
an electrical signal proportional
to the light intensity.
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19. Thanks!
Any questions
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?