2. INTRODUCTION:
• Atomic Spectroscopy is assumed to be the
oldest instrumental method for the
determination of elements. These techniques
are introduced in the mid of 19th Century,
2
3. • Bunsen and Kirchhoff showed that
the radiation emitted from the
flames depends on the
characteristic element present in
the flame.
3
The potential of atomic
spectroscopy in both the
qualitative as well as
quantitative analysis were
then well established.
4. 4
It is divided into three types which are
• Absorption Spectroscopy
• Emission Spectroscopy
• Luminescence Spectroscopy
Another branch of Atomic Absorption Spectroscopy is
• Flame Photometry or Flame Atomic Emission
Spectrometry (in which the species is examined in the form of
atoms)
• Atomic Absorption Spectrophotometry (AAS)
• Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-
AES)
Atomic spectroscopy is an
unavoidable tool in the field of
analytical chemistry.
5. INTRODUCTION:
• Flame photometry (more accurately called Flame
Atomic Emission Spectrometry)is a branch of
spectroscopy in which the species examined in the
spectrometer are in the form of atoms.
• A photoelectric flame photometer is an instrument
used in inorganic chemical analysis to determine
the concentration of certain metal ions among
them sodium, potassium, calcium and lithium.
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6. • Flame Photometry is based on measurement
of intensity of the light emitted when a metal
is introduced into flame.
– The wavelength of colour tells what the element
is (qualitative)
– The colour's intensity tells us how much of the
element present (quantitative)
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7. • The basic principle upon which Atomic
Spectroscopy works is based on the fact that
"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.
7
9. • When a metal salt solution is burned, the
metal provides a colored flame and each
metal ion gives a different colored flame.
• Flame tests, therefore, can be used to test for
the absence or presence of a metal ion.
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10. BASIC CONCEPT:
• Liquid sample contaning metal salt
solution is introduced into a flame
• Solvent is first vaporized, leaving
particles of solid salt which is then
vaporised into gaseous state
• Gaseous molecule dissociate to give
neutral atoms which can be excited
(made unstable) by thermal energy of
flame
10
11. • The unstable excited atoms emit photons while returning
to lower energy state
• The measurement of emitted photons forms the basis of
flame photometry.
11
12. • Under constant and controlled conditions the
• The light intensity of the characteristic wavelength
produced by each of the atoms is directly proportional
to
• the number of atoms that are emitting energy,
• which in turn is directly proportional to the
concentration of the substance of interest in the
sample.
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13. Principle
• When a solution is aspirated into a low temperature flame,
in an aerosol, each droplet of water evaporates leaving a
solid core of the residue of evaporation.
• The core further breaks down to the molecular level, and
provided the molecules are not too refractory, progress to
form atomic species.
13
14. • The atom then is excited by the flame and its
electron temporarily moves to a higher energy
state.
• When the electrons return to the ground state,
they lose the excitation energy and a discrete
wavelength of visible light is emitted.
14
15. • The emitted light can be isolated from other light
wavelengths by an optical filter.
• The amount of light being emitted is proportional to
the number of atoms in the flame, and it follows, the
conc. of that atom in the original solution.
15
16. • The amount of light emitted can be measured
by a suitable photo detector.
• A photo detector generates an electrical signal
which is amplified and displayed on a digital
readout.
16
18. Structure of Flame:
As seen in the figure, the
flame may be divided into
the following regions or
zones.
– Preheating zones
– Primary reaction zone or
inner zone
– Internal zone
– Secondary reaction zone
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19. • It should have proper temperature
• Temperature should remain constant
throughout the operation
• There should not be any fluctuation during
burning
19
20. • 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.
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21. • 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.
21
22. 22
Name of the
element
Emitted wavelength range
(nm)
Observed color of the
flame
Potassium (K) 766
Violet
Lithium (Li) 670
Red
Calcium (Ca) 622
Orange
Sodium (Na) 589
Yellow
Barium (Ba) 554
Lime green
23. To convert the analyte of the liquid sample into
vapour state
To decompose the analyte into atoms and simple
molecules
To excite the formed atoms/free atoms/simple
molecules to emit radiant energy
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26. Sample Delivery System:
There are three components for introducing liquid
sample:
• Nebulizer – it breaks up the liquid into small
droplets.
– Nebulization the is conversion of a sample to a mist of
finely divided droplets using a jet of compressed gas.
– The flow carries the sample into the atomization region.
– 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
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28. 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.
•Premixed burner (used widely)
•Mecker Total consumption.
•Lundergarh.
•Shielded burner.
•Nitrous oxide-acetylene flames
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30. 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
30
32. Detectors:
– Photomultiplier tubes
– Photo emissive cell
– Photo voltaic cell
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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33. 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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34. 34
Element wavelength Detection
limit
Element wavelength Detection
limit
Al 396 0.5 Pb 406 14
Ba 455 3 Li 461 0.067
Ca 423 0.07 Mg 285 1
Cu 325 0.6 Ni 355 1.6
Fe 372 2.5 Hg 254 2.5
Elements, their characteristic emission wavelengths
and detection limits
35. APPLICATION
• Flame photometer has both quantitative and qualitative
applications.
• Flame photometer with mono-chromators emits radiations
of characteristic wavelengths which help to detect the
presence of a particular metal in the sample.
• To estimate sodium, potassium, calcium, lithium etc. level in
sample of serum, urine, CSF and other body fluids.
• Na+ and K+ ions in, muscles and heart can be determined by
diluting the blood serum and aspiration into the flame.
36. INTERFERENCES:
• In determining the amount of a particular element
present, other elements can also affect the result.
Such interference may be:
• Spectral 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
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37. • Ionic interferences: high temperature flame may cause
ionisation 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.
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38. • Chemical interferences: The chemical interferences arise out of
the reaction between different interferon's and the analyte.
Includes:
i. Cation-anion interference:
– The presence of certain anions, such as oxalate, phosphate,
sulfate, in a solution may affect the intensity of radiation
emitted by an element.
ii. Cation-cation interference:
– These interferences are neither spectral nor ionic in nature
– Eg. aluminum interferes with calcium and magnesium.
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39. ADVANTAGES
• Simple quantitative analytical test based on the
flame analysis.
• Inexpensive.
• The determination of elements such as alkali and
alkaline earth metals is performed easily with most
reliable and convenient methods.
• Quite quick, convenient, and selective and sensitive
to even parts per million (ppm) to parts per billion
(ppb) range. 39
40. Disadvantages
• The concentration of the metal ion in the
solution cannot be measured accurately.
• A standard solution with known molarities is
required for determining the concentration of
the ions which will corresponds to the
emission spectra.
• It is difficult to obtain the accurate results of
ions with higher concentration.
41. • The information about the molecular
structure of the compound present in the
sample solution cannot be determined.
• The elements such as carbon, hydrogen and
halides cannot be detected due to its non-
radiating nature.
41
42. REFERENCES:
• 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.
• http://www.hindawi.com/journals/chem/2013/465825/
• Practical Biochemistry, Principles & Techniques,
Cambridge low-price editions, 5th Edition, Edited By Keith
Wilson & John Walker, Chapter: Spectroscopic Techniques,
Pages : 486-490.
43. • 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.
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