3. SPECTROSCOPY
• Spectroscopy is the branch of science that
deals with the study of interaction of
electromagnetic radiations with matter i.e.
atoms or molecules of drugs.
• Spectroscopy is of two types, Emission
spectroscopy and absorption spectroscopy.
5. ATOMIC SPECTROSCOPY
• Atomic Spectroscopy is the result of
phenomenon of absorption, emission or
fluorescence by atoms or elementary ions
mostly in ultraviolet region.
• The spectra are obtained by converting the
component into gaseous atoms or elementary
ions by suitable heat treatments.
7. ATOMIC LINE WIDTH AND PRINCIPLE
OF ATOMIC ABSORPTION
SPECTROSCOPY
BY: MAZNA SALEEM
8. ATOMIC LINE WIDTH
• The width of atomic lines are of considerable
importance in atomic absorption or atomic
emission spectroscopy.
• Narrow lines are highly desirable for both
absorption and emission spectroscopy because
they reduce the possibility of interferences due to
overlapping spectra.
9. PRINCIPLE OF AAS:
The technique uses basically the principle that
free atoms (gas) generated in an atomizer can
absorb radiation at specific frequency.
Atomic-absorption spectroscopy quantifies the
absorption of ground state atoms in the gaseous
state .
The atoms absorb ultraviolet or visible light and
make transitions to higher electronic energy
levels.
The analyte concentration is determined from
the amount of absorption.
12. PROPERTIES
• It is a techniques are used to measure the
concentration of solutes in a solution.
• It is the quantitative measurement of the reflection
or transmission properties of a material.
• It is use in various fields such as chemistry, physics,
biochemistry, and chemical engineering and clinical
applications.
16. RADIATION SOURCES
• Absorption Lines are very much narrow (0.002
to 0.005)
• This limited lines creates problem in AAS.
• The problem's solution is nothing but the
Radiation Sources.
17. LAMP SOURCES
A separate lamp source is needed for each
element or sometimes group of element.
• Hollow Cathode lamp
• Electrodeless discharge lamp.
18. HOLLOW CATHODE TUBE
Apparatus:
• Tungston anode.
• Cylindrical cathode.
• Glass container.
Ionization of inert gas occurs when it is
supplied with:
• 300V potential
• 5 to 20mV current.
19. WORKING OF HCL
• HCL works by the process of sputtering.
‘Sputtering occurs when the energy to be
transformed into gaseous atom and bring out an
atomic cloud by shifting some amount of metal
from the cathode.’
• The excited metal atoms of the atomic cloud
emits the radiation.
• Metal atom diffuse back thus re-deposition
occurs.
20. ELECTRODE LESS DISCHARGE LAMP
• Small amount of both inert gas and the
element to be studied is placed inside the
tube constructed with quartz glass.
• Unlike HCL it is devoid of any electrodes but
alternatively microwave radiation is present to
provide power from outside the lamp.
21. WORKING OF EDL
• EDL is available foe wide variety of elements.
It is more efficacious practically but expensive.
38. PHOTO TUBE
• It consists of Semi-
cylindrical cathode
(containing loosely
bounded electrons) and
central metal wire
anode.
• The current produce
from the photo tube are
quite small so it require
amplification.
39. PHOTOMULTIPLIER TUBE
• The principle of
operation is the
emission of
electrons upon
exposure to
radiation.
• The detector
contains a photo
emissive cathode
and a series of
dynodes.
42. SPECTRAL INTERFERENCES
This type of interference normally takes place
when the absorption of an interfering species
either overlaps or lies very near to the analyte
absorption.
Examples of spectral interferences,
• Combustion products.
• Emission line of element, radical or molecule
and unresolved band spectra.
• Sample Matrix
43. CHEMICAL INTERFERENCES
• It results from various chemical processes
occurring during atomization that alter the
absorption characteristics of the analyte.
• More common.
• effects may often be minimized by
appropriate choice of experimental
parameters.
44. • Examples :
(i) Chemical Interferences due to Anion (PO43–)
(ii) Chemical Interference due to Cations.
45. PROTECTIVE AGENTS :
These agents are found to inhibit the
interferences by virtue of their ability to form
relatively stable but volatile species with the
respective analyte.
(a) EDTA.
(b) 8-Hydroxyquinoline, and
(c) Ammonium salt of APDC.
46. IONIZATION INTERFERENCES
The substitution of air with either oxygen or
nitrous oxide gives rise to temperatures which
are high enough to cause appreciable
ionization. Hence, as a consequence of the
attained equilibrium-a fairly significant
concentration of electron exists.
M M + e–
48. SINGLE BEAM
SPECTROPHOTOMETER
• It utilizes one beam of light that passes through the
sample and the intensity of the light reflected from
a reference is measured without sample.
49. ADVANTAGES
• Low cost
• High throughput
• High sensitivity
• Less complicated
• Economical
DISADVANTAGES
• Calibration should be done with blank and sample
continuously according to wavelength and
absorption power of sample so reference beam is
not obtain simultaneously.
• Time consuming
50. DOUBLE BEAM
SPECTROPHOTOMETER
It utilizes two beams of light: reference and sample
beam.
Double beam spectrophotometer use rotating mirror
to separate the reference beam from a sample beam.
51. ADVANTAGES
Double beam is more advantageous then single
beam.
• High speed
• High stability
• Flexibility
DISADVANTAGES
• expensive
• Lower sensitivity
• Lower reliability
53. APPLICATIONS
• One of the most widely used techniques.
• Its popular for quantitative analysis
a) molecular weight determination
b) detection of conjugation
c) detection of functional groups
• and qualitative analysis.
a) detection of impurities to analyze substance purity .
• Assay of trace metals and determination elements.
• Importance of AAS In its modern form.
