Colorimetry uses the light absorbing properties of solutions to measure concentration. It follows Beer's and Lambert's laws - the amount of light absorbed is directly proportional to the concentration and path length of the solution. The photoelectric colorimeter is commonly used to measure substances in blood and body fluids. It has advantages like being inexpensive and portable but cannot analyze colorless compounds or work in some light regions.

1. VISHALRAJ K
HCA20M10

2. *CONTENT*
Introduction
Principle
Beer’s law
Lambert’s law
Photoelectric colorimeter
Uses
Advantages & Disadvantages

3. *INTRODUCTION*
Colorimetry is the technology used in science
labs to measure the concentration of a
solution from its light absorbing properties.
It is similar to spectrophotometry.
Colorimetry was invited in the
year of 1870 by Louis J Doboscq.

4. *PRINCIPLE*
When a monochromatic light passes through
a coloured solution, some specific wavelength
of light are absorbed which is related to
colour intensity.

5. Log IO/IE = KCT
K > Constant
C > Concentration
T > Thickness
IO > Intensity
IE > Emitted
The amount of light absorbed or transmitted
by a colour solution is in accordance with two
law i.e. Beer’s & Lambert’s law.

6. *BEER’S LAW*
According to this law the amount of light
absorbed is proportional to the concentration
of the solute.
Intensity of the emitted light (IO) decreased
with increase in concentration.

7. *LAMBERT’S LAW*
The lambert’s law states that the amount of
light absorbed is directly proportional to the
length and thickness of the solution under
analysis.
Intensity of emitted light (IO) decreased with
increase in thickness and length.

8. *PHOTOELECTRIC COLORIMETER*
The Photoelectric colorimeter is commonly
employed for measurement of different
substance in the blood like glucose, blood
urea, blood enzymes, and others.
It is used for measuring the transmittance
and absorbance of light passing through a
liquid sample.

9. The different types of colorimeter are single
beam filter photometer, double beam
photometer, probe - type photometer, multi –
channel photometer, and portable photometer.
The colorimeter is widely used
in biochemical laboratories for
quantitative analysis of
specific substances in human
body fluids (blood and urine).

10. It measures absorbance and wavelength
between 400 to700 nm i.e. from the visible
spectrum of light of the electromagnetic
spectrum.
The light (tungsten lamp) passes through a
condensing lens .
And the filter helps to split a beam of light into
different wave lengths allowing only the
required wavelength to pass through it reach
the solution.

11. When the beam of light reaches solution, it is
transmitted, reflected, and absorbed by the
solution.
The transmitted rays falls on the photocell
system where it measures the intensity of
transmitted light.
Photocell converts it into the electrical signals
and send it to the galvanometer.
The electric signals measured by the
galvanometer are displayed in the digital
form.

12. *USES*
It is used in laboratories and hospitals to
estimate biochemical sample such as urine,
cerebrospinal fluid, plasma, serum, etc…
Used in quantitative analysis of proteins,
glucose, and other biochemical compounds.
Such as used to test water quality.
And to determine the concentration of
haemoglobin in the blood.

13. *ADVANTAGES & DISADVANTAGES*
Some benefits are as follows:
It is an expensive method, widely used in the
quantitative analysis of coloured samples,
easy to carry, and transport.
Some disadvantages are as follow:
Analysis of colourless compound is not
possible, does not working in IR and UV
regions.