PPT on Atomic absorption spectroscopy

1. SOS IN ENVIRONMENTAL CHEMISTRY
JIWAJI UNIVERSITY
GWALIOR
PRESENTATION ON – ATOMIC ABSORPTION
SPECTROSCOPY
Presented to Presented by
Dr . NIMISHA JADON AKASH SAXENA
(Assistant Professor) M.Sc. ICA (2nd
SEM)

2. CONTENTS
Introduction
History
Principle
Instrumentation
Interferences
Advantages
Disadvantages
Applications
References

3. HISTORY
Atomic absorption spectroscopy is deals with the
absorption of specific wave length of radiation by
neutral atoms in the ground state.
 The first atomic absorption spectroscopy was
built by CSIRO scientist Alan Walsh & Co-
Workers in Melbourne in 1954
 The first commercial AAS was introduced in
1959. Alan Walsh
(1916-
1998)
INTRODUCTION

4. PRINCIPLE
When solution of metallic salt is sprayed on to a
flame, fine droplets are formed due to the thermal
energy of flame. The solvent in the flame is
evaporated, leaving fine residue, which are
converted to neutral atoms. These neutral atoms
absorb radiation of specific wavelength emitted by
Hollow Cathode Lamp.
For the determination of every element, specific
Hollow Cathode Lamp is used.

5. LIQUID
SAMPLE
FORMATION
OF
DROPLETS
FINE
RESIDU
E
FORMATION
OF
NEUTRAL
ATOMS
NEUTRAL ATOMS
ABSORB SPECIFIC
WAVELENGTH OF
RADIATION
MEASUREMENT OF
INTENSITY OF RADIATION
BY USING PHOTOMETRIC
DETECTOR

6. FIG: Instrumental setup for atomic absorption
spectroscopy
INSTRUMENTATION

7. 1. LIGHT SOURCE
 The light source is usually a Hollow
Cathode Lamp of the element that is
being measured.
 It consist 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.
Fig: HOLLOW CATHODE
LAMP

8. FLAME

9. Temperature profile when fuel is Natural Gas and oxidant is Air

10. 2. ATOMIZER
Atomization is done by exposing the analyte to high temperature in a
flame or electro thermal atomizer.
(i). Flame Atomizer
The most common way is to use a flame which is used for converting
the liquid sample into the gaseous state.
There are two types of flame atomizer;
(a).Total Consumption Burner
(b).Premixed Burner
Types of atomizer
There are two types of atomizer

11. (a). Total Consumption burner (b). Premixed burner

12. (ii). Electro thermal atomizer
In electro thermal atomizer firstly
sample is evaporated at a low
temperature and then it is
converted into ash by increasing
the temperature after ashing, the
temperature is increased from
2000-3000C. Atomization of
sample occur in few seconds
Commonly used electro thermal
atomizer is Graphite tube.
Graphite tube
HCL

13. 3. SAMPEL INTRODUCTION SYSTEM
In atomizer, sample is constantly introduced in form of droplets.
NEBULIZER:
A device for converting sample into fine spray or droplets.
Capillary
Nebuliser
Sample Solution

14. 4. MONOCHROMATER
Monochromater is used to separate out all of the thousand of
lines.
In AAS Prism OR Grating system is used as a monochromater.
5. DETECTORS
For AAS Photomultiplier tube is used.
6. READOUT DEVICE
In AAS, measurement chart recorder is used as readout device.

15. INTERFERENCES
Different types of interferences which affect AAS are as
follows-
1. Spectral Interference
2. Chemical Interference
3. Ionization Interference
4. Solvent Interference

16. ADVANTAGES
Equipment relatively cheap
Easy to use (training easy compared to
furnace)
Good precision
High sample throughput
Relatively easy method development
Cheap to run

17. DISADVANTAGES
Lack of sensitivity (compared to furnace)
Problems with refractory elements
Require large sample size
Sample must be in solution

18. APPLICATIONS
1. Qualitative Analysis
2. Quantitative Analysis
3. Estimation of trace elements in biological fluid
like blood, urine, etc.
4. Estimation of trace elements like Copper , Nickel
and Zinc in food products.
5. Estimation of Lead in petrol.
6. Estimation of elements in soil samples , water
supply , effluents , ceramics , etc.

19. REFERENCES
Principles of Instrumental Analysis, 6th Edition
(Douglas A. skoog)
Instrumental Methods of Chemical analysis 5th Edition
(Gurdeep R. Chatwal)
The application of Atomic Absorption Spectra to Chemical
analysis (A. Walsh (1995))
Wikipedia