colorimetry

#COLORIMETRY #biophysics #science

1. VISHALRAJ K HCA20M10 COLORIMETRY

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.

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