Flame photomerty

A brief introduction to flame photometry [Pharmaceutical Analysis]

1. FLAME PHOTOMERTY BASIC CONCEPTS , INSTRUMENTATION, APPLICATIONS AND LIMITATIONS . BY, Chaluvadi Pujitha ( B – Phamacy ) Bapatla College of Pharmacy,Bapatla . December,2020.

2. CONTENTS :- Introduction General principles Instrumentation Instruments Applications Limitations

3. INTRODUCTION:- Flame photomerty is also named as flame emission spectroscopy because of the use of a flame to provide the energy of excitation to atoms introduced into the flame It is based on the measurement of intensity of the light emitted when a metal is introduced into a flame. The wavelength of the colour tells us what the element is , and the colour’s intensity tells us how much of the element is present .

4. GENERAL PRINCIPLES :- The basic principle is "Matter absorbs light at the same wavelength at which it emits light ".  Atoms of elements subjected to hot flame specific quantum of thermal energy absorbed by orbital electrons become unstable at high energy level release energy as photons of particular wavelength change back to ground state. Energy Level Of Electron ( E2 –E1) ∆ E= E2-E1= h ν ∆E = h ν ∆ E = hc / λ ( v=c/ λ ) ∆ E = Energy difference h = Plank’s constant(6.626068 X 10-34 m2 kgs-1 ) ν = frequency of emitted light c = velocity of light

5. FLAME PHOTOMETER INSTRUMENT:- Laboratory Use Industrial Use

6. STRUCTURE OF FLAME:- The flame may be divided into The following zones - Preheating zone - Primary reaction zone or inner zone - Internal zone - Secondary reaction zone

7. • Preheating zone- In this, combustion mixture is heated to the ignition temperature by thermal conduction from the primary reaction zone. • P rimary reaction zone- This zone is about 0.1 mm thick at atmospheric pressure – There is no thermodynamic equilibrium in this zone and the concentration of ions and free radicals is very high. – This region is not used for flame photometry. • I nternal zone – It can extend up to considerable height. The maximum temperature is achieved just above the tip of the inner zone. – This zone is used for flame photometry. • S econdary reaction zone - In this zone, the products of the combustion processes are burnt to stable molecular species by the surrounding air.

8. INSTUMENTATION :-

9. VARIOUS COMPONENTS OF INSTUMENT :- 1.BURNERS :- Mecker burner Total consumption burner It is used for the In this burner the study of alkali fuel and oxidant metals only. are hydrogen and o2 gas . Premix of laminar-flow burner Lundergarph burner In this burner the gases move in turbulent fashion in laminar flow

10. 2. Mirrors:- In order to maximize the amount of radiation used in the analysis,a mirror is located behind the burner to reflect the radiation back to the entrance slit of the monochromator. This mirror is concave and covers as wide a solid angle from the flame as possible. 3. Slits:- These are used before and after the dispersion elements. The entrance slit cuts and the mirrored reflection from the surrondings and allows only the radiation from the flame and the mirrored reflection of the flame to enter the optical system 4.Monochromator:- Prism : Quartz material is used for making prism, as quartz is transparent over entire region. Grating: it employs a grating which is essentially a series of parallel straight lines cut into a plane surface. 5.Detectors:- The radiation coming from the optical system is allowed to fall on the detector which measures the intensity of radiation falling on it . - Photomultiplier tubes , Photo emissive cell, Photo volatile cell

11. Read-out Device :- • It is capable of displaying the absorption spectrum as well absorbance at specific wavelength . • Nowadays the instruments have microprocessor controlled electronics that provides outputs compatible with the printers and computers . • Thereby minimizing the possibility of operator error in transferring data .

12. INSTRUMENTS:- FIRST TYPE SECOND TYPE In this Lithium is used as internal standard.

13. APPLICATION :- To estimate sodium, potassium, calcium, lithium etc. level in sample serum , urine, CSF and other body fluids . Flame photometry is useful for the determination of alkali and alkaline earth metals . Used in determination of lead in petrol. Used in the study of equilibrium constants involving in ion exchange resins . Used in determination of calcium and magnesium in cement . Qualitative Analysis:- The method is less reliable than atomic absorption spectroscopy. This does not provide information about the molecular structure of compound present in the sample solution. Non-radiating elements , such as carbon , hydrogen an halides cannot be detected by flame photometer.

14. LIMITATIONS:- The accurate concentration of the metal ion in the solution cannot be measured . It cannot directly detect and determine the presence of inert gases . Though this technique measures the total metal content present in the sample, it does not provide the information about the molecular structure of the metal present in the sample . Flame photometry cannot be used for the direct determination of each and every metal atom. A number of metal atoms cannot be analysed by this method. The elements such as carbon, hydrogen and halides cannot be detected due to their non-radiating nature .

15. REFERENCES :- Instrumental methods of chemical analysis by Gurdeep R. Chatwal , Sham K. Anand  Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. • Basic Clinical Biochemistry Practice, second edition, editied by O. A. Afonja. • College Analytical Chemistry, Himalaya Publishing House, 19th Edition (2011), By K.B.Baliga et al. Chapter 4 - Optical Methods, Pages : 135-148 .

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