Flame photometry is a technique used to analyze sodium, potassium, lithium, calcium, and barium concentrations in solutions. It works by nebulizing a liquid sample into a flame, which excites the metal atoms. As the atoms return to the ground state, they emit light at characteristic wavelengths. A monochromator separates this light, which is measured with a detector. The light intensity is directly proportional to the metal's concentration. Interferences can occur from spectral overlap, ionization, or chemical reactions with other sample components. Applications include analyzing foods, beverages, pharmaceuticals, and more. Quantitative analysis is performed using calibration curves or standard addition methods.

1. ASSIGNMENT OF SUBJECT
INSTRUMENTAL METHOD OF ANALYSIS
PRESENTED BY –
ANTA SHARMA , ROLL NO. (4)
ARYAN GAUR, ROLL NO. (5)

2. Principle
Interferences
Instrumentation
Application
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3. During 1980s Bowling Barnes, David Richardson, John Berry and Robert Hood developed an
instrument to measure the low concentrations of sodium and potassium in a solution. They
named this instrument as Flame photometer.
Flame photometry is one of the branches of atomic absorption spectroscopy in which the
species examined in the spectrometer are in the form of atoms.
It is also known as flame emission spectroscopy, Currently it has become a necessary
tool in the field of analytical chemistry.
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4. There is no need for light source. Flame serves both as an as an atomizer and
excitation source. It is suitable for qualitative and quantitative determination of
several cations, especially for metals that are easily excited to higher energy levels at
flame temperature. These metals are Na, K, Ca, Ba, Li.
When sample interacts with light, absorption process occurs. Ground state
electrons of the sample atom tend to move to the excited states with the energy of
absorbed light. This process can also be called excitation.
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5. Since excited state is unstable, electrons want to return back to the
ground state. When an excited electron turns back to its ground state a
radiation is emitted that is equal to the energy difference between
excited and ground states.
The emitted light is monochromatic and it has the same wavelength as
the light absorbed in the excitation process.
 Depending on the excitation technique, absorbed or emitted light is
measured. If excitation source is flame, emitted radiation is measured.
On the other hand, absorption is measured when lamp is used for
excitation. Both are directly proportional with the number of atoms in the
sample.
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6. The principle of flame photometer is based on the measurement of the emitted light intensity
when a metal is introduced into the flame.
The wavelength of the colour gives information about the element and the colour of the flame
gives information about the amount of the element present in the sample.
The compounds of the alkali and alkaline earth metals (Group II) dissociate into atoms when
introduced into the flame. Some of these atoms further get excited to even higher levels. But
these atoms are not stable at higher levels.
Hence, these atoms emit radiations when returning back to the ground state. These
radiations generally lie in the visible region of the spectrum. Each of the alkali and alkaline
earth metals has a specific wavelength.
For certain concentration ranges, The intensity of the emission is directly proportional to the
number of atoms returning to the ground state. And the light emitted is in turn proportional to
the concentration of the sample.
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7. Liquid sample containing metal salt solution is
introduced into a flame
Solvent is first vaporized, leaving particles of solid salt,
salt is then vaporized into gaseous state Gaseous
molecule dissociate to give neutral atoms which can be
excited (made unstable) by thermal energy of flame.
The unstable excited atoms emit photons while
returning to lower energy state.
When the atoms return to the ground state, radiation of
the characteristic element is emitted.
The intensity of emitted light is related to the
concentration of the element.
A brief overview of the process
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8. Characteristic colour produced by each element
Elements Emitted
Wavelength
Flame Colour
Sodium 589 nm Yellow
Potassium 766 nm Violet
Barium 554 nm Lime green
Calcium 622 nm Orange
Lithium 670 nm Red
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FLAME PHOTOMETRY ASSIGNMENT

9. Preheating zone- In this, combustion mixture is
heated to the ignition temperature by thermal conduction
from the primary reaction zone.
Primary 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.
Interconal 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.
Secondary reaction zone - In this zone, the
products of the combustion processes are burnt to stable
molecular species by the surrounding air.
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10. Interferences have played a very prominent role in measurement of metal ions in a solution also in
determining the amount of a particular element present.
Whereas, other elements can also affect the result.
Such interference may be of 3 kinds:
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A) Spectral
interference
B) Ionic interferences
C) Chemical
interferences
occurs when the emission lines of
two elements cannot be resolved or
arises from the background of flame
itself.
They are either too close, or
overlap, or occur due to high
concentration of salts in the sample
 high temperature flame may
cause ionization of some of the
metal atoms, e.g. sodium.
The Na+ ion possesses an
emission spectrum of its own with
frequencies, which are different
from those of atomic spectrum of
the Na atom.
Cation-cation
interference
Cation-anaion
interference
The chemical interferences
arise out of the reaction
between different
interferents and the analyte.
Includes:

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Cation-anion interference Cation-cation interference
The presence of certain
anions, such as oxalate,
phosphate, sulfate, in a
solution may affect the
intensity of radiation emitted
by an element. E.g.,
calcium + phosphate ion
forms a stable substance, as
Ca3(PO4)2 which does not
decompose easily, resulting
in the production of lesser
atoms.
These interferences are
neither spectral nor ionic in
nature
 Eg. aluminum interferes
with calcium and magnesium.

12. There are two types of Flame Photometers that are used invariably in Flame
Emission Spectroscopy (FES), namely :
(a) Simple Flame Photometer, and
(b) Internal Standard Flame Photometer.
(a) Simple Flame Photometer:- Flame Photometers are designed and intended
mainly for carrying out the assay of elements like :Na, K, Ca & Li that possess the
ability to give out an easily excited flame spectrum having sufficient intensity for
rapid detection by a photocell.
(b) Internal Standard Flame Photometer:- To eliminates the visible effects of
momentary fluctuations in the flame characteristics produced by variations in
either the oxidant or under full pressures .
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13. SIMPLE FLAME PHOTOMETER INTERNAL STANDARD FLAME PHOTOMETER
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14. Major Components:
1. Source
2. Sample delivery
system
3. Monochromator
4. Detector
5. Read out device
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15. 1) SOURCE:-
• A Burner used to spray the sample solution into fine droplets.
• Several burners and fuel + oxidant combinations have been used to produce analytical flame
including: Premixed, Mecker, Total consumption, Lundergarh, Shielded burner, and Nitrous oxide
acetylene flames
• Pre-mixed Burner: – widely used because uniformity in flame intensity – In this energy type of
burner , aspirated sample , fuel and oxidant are thoroughly mixed before reaching the burner
opening.
• Total Consumption Burner: – In this fuel and oxidant are hydrogen and oxygen gases –
Sample solution is aspirated through a capillary by high pressure of fuel and Oxidant and burnt at
the tip of burner – Entire sample is consumed.
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16. Pre-mixed burner Total Consumption Burner
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17. 2) SAMPLE DELIVERY SYSTEM:-
There are three components for introducing liquid sample:
• Nebulizer – it breaks up the liquid into small droplets.
1. Nebulization is the conversion of a sample to a mist of finely divided droplets using a jet of compressed gas.
2. The flow carries the sample into the atomization region.
3. Pneumatic Nebulizers: (most common)
•Aerosol modifier – it removes large droplets from the stream and allow only smaller droplets than a certain size
to pass.
•Flame or Atomizer – it converts the analyte into free atoms.
3) 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.
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18. 4) Detectors: –
1. Photomultiplier tubes
2. Photo emissive cell
3. Photo voltaic cell
1) Photovoltaic cell:
• It has a thin metallic layer coated with silver or gold which act as electrode, also has metal
base plate which act as another electrode
• Two layers are separated by semiconductor layer of selenium, when light radiation falls on
selenium layer.
• This creates potential diff. between the two electrode and cause flow of current.
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19. 2) Photo multiplier tubes:-
The photomultiplier tube is an instrument that converts
light to electrical signal.
It detects and amplifies the electrons that are produced
by the photocathode. The photocathode, when stimulated
by light photons, eject electrons.
The PMT is attached to the back of the crystal.
3) Photo emissive cell:-
It consist of cathod and an anode mounted in a
vaccum tube made up of glass.
When radiation of frequency above the threshold
frequency falls on the cathode, electrons are
emitted and flow to the anode constituting an
electic current.
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20. 5) 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.
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21. Advantages:-
1. Simple quantitative analytical test
based on the flame analysis.
2. Inexpensive.
3. The determination of elements such as
alkali and alkaline earth metals is
performed easily with most reliable and
convenient methods.
4. Quite quick, convenient, and selective
and sensitive to even parts per million
(ppm) to parts per billion (ppb) range.
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Disadvantages:-
1. The concentration of the metal ion in the
solution cannot be measured accurately
2. A standard solution with known molarities is
required for determining the concentration of
the ions which will corresponds to the
emission spectra.
3. It is difficult to obtain the accurate results of
ions with higher concentration..
4. The information about the molecular structure
of the compound present in the sample
solution cannot be determined.
5. The elements such as carbon, hydrogen and
halides cannot be detected due to its non
radiating nature.

22. 1) Interference by other elements in not easy to be eliminated.
2) The elements such as carbon, hydrogen and halides cannot be detected due to its non
radiating nature.
3) It is difficult to obtain the accurate results of ions with higher concentration.
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QUALITATIVE ANALYSIS QUANTITATIVE ANALYSIS
a. Chemical industry For final
inspection or inbound inspection
of chemical products.
b. Cement Industry Review of
sodium, potassium or calcium
content in the construction and
cement industries.
a) Pharmaceutical Industry
b) Beverage industry
c) Food industry
d) Environmental analysis
e) determine the availability of
alkali and alkaline earth metals
i. Direct comparison method
ii. Calibration curve method
iii. Standard addition method
iv. Internal standard method

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