Flame photometry and Colorimetry.pdf

Instrumental analysis of AAS, Flame photometry and colorimetry is explained

1. ATOMIC ABSORPTION
SPECTROSCOPY
DR. SWASTIKA N DAS
BLDEACET,
VIJAYAPUR
KARNATAKA

2. LEARNING OUTCOME
PRINCIPLE OF AAS
INSTRUMENTATION
APPLICATIONS

3. INTRODUCTION

4. ELEMENTS WHICH CAN BE DETECTED

5. PRINCIPLE :

6. PRINCIPLE (contd….)
Nebuliser converts liquid solution to fine particles of aerosol/mist
Solvent gets vaporized leaving behind the solid residue
The solid residue gets vaporised due to high temperature of the flame and the molecule dissociate to atoms
The metal atoms absorb light of its own characteristic wavelength when irradiated with electromagnetic radiation
( Ni-393nm, Cu-325 nm, Na-589 nm, Li-670 nm, Ca-622 nm, Ba-554nm)
LIQUID SAMPLE
FORMATION OF
DROPLETS
FINE RESIDUE
FORMATION OF
NEUTRAL ATOMS
ABSORPTION OF
SPECIFIC
WAVELENGTH BY
NEUTRAL ATOMS
MEASUREMENT OF
INTENSITY OF RADIATION
ABSORBED BY THE
NEUTRAL ATOMS USING
DETECTOR

7. INSTRUMENTATION

9. AAS -INSTRUMENTATION

10. Schematic Diagram of AAS :

11. Radiation source
Hollow cathode lamp or a electrodeless lamp is used as a source of
light with varying wavelength range. Each element has its own unique
lamp which must be used for that analysis.

12. Burner
Air and fuel combines in the burner to produce the flame. To create
flame we need to mix fuel and oxidant. Usually air-acetylene flame
or nitrous oxide-acetylene flame is used

13. Other Components of AAS
Nebuliser and mixing chamber : Converts the liquid sample into a fine aerosol
spray to introduce into the flame. Then this aerosol is thoroughly mixed with air-
fuel mixture and spraying of the fine particles into the flame occurs .
Atomiser :Elements to be analysed are need to be in the atomic state.
Atomisation is to separate the particles into molecules and breaking down the
molecules into atoms. This is done by applying high temperature using a Flame
atomiser/electro thermal atomiser/ glow discharge atomiser / cold vapour
atomiser.
Monochromator or filter :It is used to select a specific wavelength of light which is
absorbed by the sample. And to exclude other wavelengths of light. Allows only
the chosen wavelength and absorbs all the other wavelength e.g, prism,
diffraction grating

14. Other Components of AAS
Detector:light from the monochromator falls on the
detector where the light signal is converted into current
proportional to intensity of light E.g. photocell or
photodiode.
Amplifier:the current signal is amplified and sent to the
data processor
Data processor or display: It displays the absorbance
values and process to provide relevant data.

15. APPLICATIONS :
Presence of metals in water and waste water like As,
Cd,Hg, Pb, Ca, Mg etccan be determined
Contamination of metals in food cereals, milk etc
Presence of certain metals in shampoos, wash liquids
etc.
Presence of metals in biological fluids in blood, urine,
saliva, brain tissue, muscle tissue, bones, plasma, liver
etc
Presence of metals in metallurgical products , alloys,
industrial plating baths etc
Analysis of metals present in soil, sediments and
rocks.

16. Colorimetry :

17. LEARNING OUTCOMES :
Principle of colorimetry
Instrumentation-components of a colorimeter
Absorbance, transmittance
Beer-Lambert Law
Experiment
Applications
Advantages and Disadvantages of Colorimetry

18. COLORIMETRY :

19. Principle of Colorimetry :
Substance to be measured by colorimetry must be coloured or can be made
to produce coloured derivatives by using suitable reagents and reactions.
Intensity of the colour depends on the concentration of the colour producing
substance in the solution
Coloured substance absorb light of a particular wavelength and the extent of
light absorption depends on the concentration of the solution.

20. Principle cont.……
Coloured solutions absorb a
certain amount of light when a
monochromatic light is passed
through them. The amount of light
absorbed or transmitted is in
accordance with two laws:
(i) Beer’s Law
(ii) Lambert’s Law
Beer’s Law : This law states that the intensity of the
transmitted light decreases exponentially with the
increase in concentration of the solution
OR
The amount of light absorbed (A) is directly
proportional to the concentration of the analytic
species (C) in the solution.
A αC
Lambert’s Law:This law states that
the amount of light absorbed by a
coloured solution is directly
proportional the path length of the
light (l)
Aαl

21. Absorbance or Optical Density
A= log I
0/I
t= log 1/T
Where,
T is Transmittance of light
I
t= intensity of transmitted light
I
0 = intensity of incident light

22. Components of colorimetry :

23. Instrumentation :

24. Parts of the colorimeter :

28. Experiment-Colorimetry

29. Experiment-Colorimetry

30. Experiment-Estimation of Cu.

32. Applications :

33. Advantages and Disadvantages :

34. FLAME PHOTOMETER

35. FLAME PHOTOMETRY : Introduction

36. Principle :

37. Principle :

38. Principle-Schematic representation:

39. Basic Concept

40. Basic Concept

41. Flame test colours :

42. Flame Test Colours

43. Flame photometer : Instrumentation

46. Instrumentation contd…
Burner:Air and fuel combines in the burner to produce the flame.
Nebuliser and mixing chamber : Converts the liquid sample to mist and sprays the fine
particles into the flame using the compressed jet of gases ( fuel and air)
Monochromatic Filter : Allows only the chosen wavelength and absorbs all the other
wavelengths. A prism or diffraction grating can be used as monochromators.
Detector: It detects the intensity of the emitted light coming out of the cell and
generates current proportional to it. E.g. photocell or photodiode.
Meter :It displays the intensity of the light. Intensity of emitted light is directly
proportional to concentration of the solution.

47. Applications :

48. Advantages :

49. Disadvantages :

50. Experiment : Determination of Na
•A series of standard solution of NaFis to
be prepared.
•Each solution is sprayed over the flame
and the intensity of emitted light is noted
•The calibration graph s plotted with the
concentration against the intensity of
emitted light.
•Then the unknown solution containing Na
is sprayed over the flame and intensity is
noted.
•From the calibration curve the unknown
concentration can be found.