2. INTRODUCTION
• when electromagnetic radiaton strikes on a particle in
a solution ,some of the light will be absorbed by the
particle ,some will be transmitted through the solution
and some of the light will be scattered.
• The amount of light scattered is prorportional to the
concentration of insoluble particle.
• scattered light is measured by
Turbidimetry
Nephelometer
3. Turbidimetry
Turbidimerty deals with measurement of intensity of
transmitted light. The intensity of transmitted light is inversely
proportional to concentration of suspended particles.
4. Nephelometry
Nephelometry deals with measurement of intensity of scattered
light. The intensity of scattered light is proportional to
concentration of suspended particles.
6. 2.Filter or Monochromator- converts polychromatic
light into monochromatic light.
3.Sample Cell- also known as cuvette.It is made of
glass and are rectangular in shape of width 1cm.
4.Detectors-
1.photovoltaic cell
2.phototubes
3.photomultiplier tube.
7. ▪ Factors affecting scattering of light-
1.Concentration of particles
2.Particle size
3.Molecular weight of particles
4.wavelength of radiation
1.Concentration of particles-
Intensity of light is directly proportional to concentration of
particles in sample solution.
2.Particle size- scattering of light depends upon size and
shape of particles. The amount of scattering is directly
proportional to square of effective radius of the particle.
Smaller particles will cause symmetrical scattering of light.
Larger particles will cause asymmetrical scattering of light.
8. 3.Molecular weight of particles- Small molecular
weight particles will cause less scattering of light while
larger molecular weight particles will cause more light
scattering.
4.Wavelenght of radiation- shorter wavelength
radiations are scatter to greater extent while lomger
wavelength scatter to lesser extent.
Blue light scatter more than Red light.
9. Applications
1.Determination of particle size present in suspensions.
2.Measurement of atmospheric pollutants.
3.Determinig concentration of solute in soution.
4.Determination of carbon dioxide, sugar products,and clarity
of citric acid juices.
5.Biochemical analysis- measure the growth of bacterial cell in
nutrient medium.
6. Coal, oil, rubber, plastic samples are analyzed by
nepheloturbidimetry for estimation of sulphur content.
