atomic absorption spectroscopy according to pci syllabus

1. ATOMIC ABSORPTION
SPECTROSCOPY
By
Mohammad Aashik
Bachelor of pharmacy 7th sem.

2. CONTENT
 Introduction
 Atomic absorption spectroscopy
 Principle
 Interferences
 Instrumentation
 Applications

3. INTRODUCTION
 Atomic absorption spectroscopy (AAS) is a spectro-
analytical procedure for the quantitative
determination of chemical elements using the
absorption of optical radiation by free atoms in the
gaseous state.
 It is technique for measuring quantities of chemical
elements present samples by measuring the
absorbed radiation by the chemical element of
interest.
 It can analyze over 62 elements.

4. WHAT IS AAS?
 It is a quantitative method of analysis that is
applicable to many metals and a few metals.
 The technique was introduced in 1995 by walsh in
Australia .

5.  Elements that are highlighted in pink are detectable by
AAS

6. PRINCIPLE:
 In gaseous state atoms absorb ultraviolet or visible
light and make transition to higher electronic energy
levels.
 The wavelength of each transition is specific to
each element- qualitative analysis.
 Beer-lamberts law can be applied to find
concentration using a calibration graph prepared
from standards.

7. INTERFERENCES IN ATOMIC ABSORPTION
SPECTROSCOPY:
 Analytic interference change the magnitude of the
analytic signal itself. Such interferences are usually
not spectral in nature but rather physical or
chemical effects.
 PHYSICAL INTERFERENCES:
 Physical interferences can alter the aspiration,
nebulisation, desolation and volatilization processes
.
 Substances in the sample that change the solution
viscosity.
for example:- can alter the flow rate and efficiency
of the nebulisation process.

8. CHEMICAL INTERFERENCES:
 They occur in the conversion of solid or molten
particle after desolation into free atoms or
elementary ions. Constituents that influences the
volatilization of analyte particle causes this type of
interferences and are often called solute
volatilisation interferences.
for example:- can alter in some flames the presence
of phosphate in the sample can alter the atomic
concentration of calcium in the flame owing to the
formation of relatively non volatile complexes.

9. SPECTRAL INTERFERENCES:
 Spectral interferences by elements that absorb at
analyte wavelength are rare in the atomic
absorption.
 In some case, if the source of interference is kwon,
an excess of the interfere can be added to both the
sample and the standards. The substance is
sometimes called as radiation buffer.

12. INSTRUMENT OF AAS:
 LIGHT SOURCE:-
 Hollow cathode lamp are the most common
radiation source of AAS.
 It contains a tungsten anode and a hollow
cylindrical cathode made of the ellement to be
determined.
 These are sealed in glass tube filled with inert gas
(neon & argon)

13. MONOCHROMATOR:
 This is a very important in an AAS. It is used to
separate out all of the thousands of line.
 A monochromator is used to select the specific
wavelength of light which is absorbed by the
sample, and to exclude other wavelength.
 The selection of the specific light allows the
determination of the selected element in the
presence of others

14. NEBULIZER:
 Suck up liquid samples at controlled rate.
 Create a fine aerosol sprat for introduction into
flame.
 Mix the aerosol and oxidant for introduction into
flame.

15. ATOMIZER:
 Elements to be analyzed needs to be in atomic
sate.
 Atomization is separation of particles into individual
molecules and breaking molecules into atoms. This
is done by exposing the analyte to high temperature
in a graphite furnace.

16. DETECTOR:
 The light selected by the monochromator directed
into 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 further fed into a Data station requested
format.

17. AAS ADVANTAGES AND DISADVANTAGES
 ADVANTAGES:
1) High selectivity and sensitivity
2) Fast and simple working
3) Does not need metals separation
DISADVANTAGES:
1) Analysis does not simultaneous
2) Fragment have to form ready measure solution
3) Limit types of cathode lamp (expensives)

18. APPLICATION:
 Clinical analysis:- Analysing metals in biological
fluids such as blood and urine.
 Environmental analysis:- Monitoring our
environment -e.g. Finding out the levels of various
elements in rivers, seawater, drinking water, air,
petrol and drinks such wine, beer and fruit drinks.
 PHARMACEUTICALS:- in some pharmaceutical
manufacturing process, minute quantities of a
catalyst used in the process are sometimes present
in the final products. By using the AAS the amount
of catalyst present can be determinded

19.  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 – e.g. 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.