Power point of Atomic Absorption Spectroscopy

2. Study of interaction of electromagnetic radiation
with matter.
These are the waves which is a form of
alternating current of high frequency having the same speed
as that of light.
This deals with the interaction of electromagnetic
radiation with atoms which are most commonly in their
lowest energy state called ground state

4.  Defn of spectroscopy.
 After interaction there is variation in intensity of
electromagnetic radiation.
Instrument which records this variation in intensity.
Sample itself emits radiation- Emmision spectroscopy
Sample itself absorbs radiation- Absorption spectroscopy

5. AAS is the most powerful instrumental method
for quantitative determination of trace metals in
liquids.
Gives total metal content of the sample & it is
independent on molecular form of the metal.
Determine concentration of-
- 60-70 metals
- metals
- non-metals indirect method

7. • AAS based on the absorption of energy by
ground state atoms in the gaseous state.

8. Total amount of light absorbed shown by
equation-
v light absorbed = πe2 Nf
mc
Where,
e charge on electron of mass m
c the speed of light
N total number of atoms that may absorb

9.  AAS is independent on flame temperature.
i.e. variation in flame temperatures represents
relatively less effects in AAS than in FES (flame
emission spectroscopy) in which the smaller
number of atoms are giving an emission signal.
 In terms of detection limits AAS & FES are quite
similar
 It is specific since atoms of a particular elements
can only absorbed radiation of their own
characteristic wavelength.

10. In FES the emission intensity is dependant upon the
number of exciting atoms & greatly influenced by
temperature variation whereas in AAS depends upon
number of unexcited atoms and absorption intensity
independent on temperature.
Analytical signal results from sum of all energies
emitted as excited atoms and in AAS signal is achieved
by difference in intensities in presence and absence of
liquid sample containing metals.
In AAS Beer’s law is obeyed i.e. absorption is directly
proportional to concentration. This is not true in case
of FES

11. Light source
(hollow cathode Lamp )
atomizer
monochromator
Detector and
readout device

12. The instrument consists of:
1. Light source
2. atomizer
3. Monochromator
4. Detector

13. 13
Light Source
Detector
Sample
Compartment

15. The light source is usually a hollow cathode lamp
of the element that is being measured.
 It contains a tungsten anode and a hollow
cylindrical cathode made of the element to be
determined.
These are sealed in a glass tube filled with an
inert gas (neon or argon ) . Each element has its
own unique lamp which must be used for that
analysis .

16. cathode
Anode
Quartz window
Pyrex body
Anode
Cathode

17. From bottom to
top, the lamps are for
-Mg
-Ca
-K
-combination of Fe,
Co, Ni, Mn, Cu, and Cr.
Each element uses a
specific wavelength of
light.

18. Elements to be analyzed needs to be in
atomic state
Atomization is separation of particles into
individual molecules and breaking molecules
into atoms .This is done by exposing the
analyte to high temperatures in a flame.

19. The role of the atom cell is to primarily dissolvate a liquid sample
and then the solid particles are vaporized into their free gaseous
ground state form . In this form atoms will be available to absorb
radiation emitted from the light source and thus generate a
measurable signal proportional to concentration.

20. Flame AA can only analyze solutions , where
it uses a slot type burner to increase the path
length, and therefore to increase the total
absorbance .
Sample solutions are usually introduced into a
nebuliser by being sucked up a capillary tube
.In the nebuliser the sample is dispersed into
tiny droplets , which can be readily broken
down in the flame.

24. This is a very important part in an AA
spectrometer. It is used to separate out all of
the thousands of lines. Without a good
monochromator, detection limits are severely
compromised.
A monochromator is used to select the 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.

25. The light selected by the monochromator is
directed onto 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 into a data station for
printout by the requested format.

28. 1) Quantitative & Qualitative analysis
2) Determination of metallic elements in biological
materials
3) Simultaneous multicomponent analysis
4) Determination of lead in petrol
5) Determination of metallic elements in food
industry
6) Determination of calcium, magnesium,sodium
and potassium in blood serum