TIA - Turbidimetry

This technique is used to measure and calculate the amount of transmitted and absorbed light, to determine the concentration of substances through suspended particles.

There are two techniques used to measure the scattering, which depends on the fraction of light scattered.

Material Required:

• Nephelometry: Measurement of the scattered light by the suspended particles at right angles to the incident beam. This method is mainly used for the determination of low concentration suspensions.

• Turbidimetry: measurement of the transmitted light by the suspended particles to the incident beam. This is used for the determination of the high concentration suspensions.

Principle:

Turbidity

The turbidity is the cloudiness or haziness of a sample, which can be caused by a chemical substance.

Measured in (NTU) Nephelometric Turbidity Units.

The instrument used to measure the relative clarity is a turbidimeter and the light scatterings are dependent on the physical characteristics of the sample:

• Size of particles

• Wavelength

• Distance of observation

• Concentration of particles

• Molecular weight of particles

When the light passes through the sample/ suspension, part of the incident radiant energy is dissolute by absorption, reflection, and reaction, while the remainder of light is transmitted and read, and the concentration is determined.

• Elastic way of scattering

• Inelastic way of scattering

TYNDALL’S EFFECT is the effect of light scattering in multiple directions in colloidal dispersion while showing no light in a true solution.

Turbidity

• Light Source

• Monochromator: Used to isolate a single wavelength of radiation

• Sample holder: Cuvette

• Detectors: Converts light energy into electrical signals, phototubes are commonly used