By Sunil Bhardwaj

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The main components are :

(1) BURNER: The temp. of the burner must be more then 2000 K. Burners used are of the two types: (i) Total Consumption Burner, and (ii) Premix Burner.

Total Consumption Burner: As the Sample Solution is completely burnt so it is known as total consumption burners. The fuel which are used in this case are C2H2, C3H8 or H2. The fuel is oxidized by oxidizer which are either air or nitrous oxide or oxygen diluted with N2. When the fuel and oxidizer are burnt at the tip of the burner. The large amount of heat is produced, so the air present In the capillary expand creating a partial vacuum in the capillary, because of vacuum the sample solution is rushed to the tip of the burner.

Now, the principle start, the sample is broken into the fine spray at the upper tip of the capillary and then mixed with the gases and are burnt. This process is known as Nebulization. In the principle, some of the gaseous metallic atoms absorb the heat energy so transition take place return to original state with emission of radiations which are obtained in the form of the flame.

Merits and demerits of the burners:a) The flame obtained is turbulent.
b) It is noisy.
c) It has small area of cross-section
d) Used for most types of the flame.

Premix Burner: In this case sample solution fuel and oxidizer are well mixed with the help of axle having the baffles. In this case only a small droplet of sample can reach to the flame and large droplets of the sample is collected at the bottom in drain. Only 5% of the sample is burnt where as 95% is Condensed and drained.

Merits and Demerits:a) Flame produced is non-turbulent.
b) The flame is noiseless and stable,
c) It has large area of cross-section.
d) 5% of the sample is burnt while 95% is drained.

(2) CONCAVE MIRROR: All the radiations which are emitted by the exited atoms are collected by the Concave-mirror and are passed to monochromator.

(3) MONOCHROMATOR: The radiations are dispersed into the different wavelengths by rotating the Prism (monochromator). The radiations of one value of wavelength are incident at a time on photo-cell.

(4) PHOTOCELL: A beam from monochromator falls on photocathode of photo cell. The current is recorded. The magnitude of electric current is directly proportional to the concentration of the solution. The photo cell used Is P.M.T. (Photo-multiplier tube)

(5) READ-OUT METER: This meter gives us directly the Intensity of radiation which is emitted by the excited atoms when they return to the ground state.

Working:

When the fuel is burnt at the tip of burner the sample sol n. rushes upward then tile solvent is vaporized. Solid molecules and then gaseous atoms are formed. Some of the gaseous metallic atoms absorb heat energy and jump to the excited state and instantaneously returned to the ground state with emission of radiations which are collected by concave mirror and are incident after passing through monochromator (prism). The current is produced in the photocell and it is connected with read-out meter which give us directly the intensity of radiations emitted by the excited atoms. From this Intensity, we can have the quantitative analysis.

Application:

1. Flame photometry is specially used in accurate analysis of alkali and alkaline earth metals.
2. The process of analysis is very simple, fast and reliable.
3. The flame photometry is used in the quantitative analysis by using standard Curve method.
4. The amount of metals present in the waste water (especially alkali and alkaline earth metals) can be detected.
5. With the help of flame photometry we can determine the hardness of water.
6. It is used to determine Na, K, Ca, Zn present in the cement.
7. It is used in the determination of lead present in the petrol.
8. The phenomenon is used in the determination of tetra ethyl lead (TEL) and Manganese present In the gasoline stock.
9. We can determine the amount of baron present in an organic compound.
10. Detection of Na+, K+, Ca+2, Al+3, Fe+2 and Co+3 present in biological fluids and tissues can be done with the help of flame photometry.

Limitations:

1. It gives the total metal content present in the soln It does no give any idea about the molecular conditions of metals.
2. It is used for analysis of alkali and alkaline earth metal, specially.
3. Non-radiating elements like carbon, hydrogen and halogens cannot be detected by this method.
4. Only solutions can be analyzed.
5. For alkali and alkaline earth metals low temp. of the flame is required, because their I.P. is low so at higher temp. those metals are ionized. This ionization decrease the intensity of light emitted, so low temp. is required.

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