Basics of flame photometry provided in a student-friendly perspective.

1. Presentation on
Flame Photometry
Prajjwal Ray
PG Second Semester
Department of Environmental Biology and Wildlife Sciences
Cotton University, Guwahati 781001, Assam.

2. Flame Photometry
What is it?
• Flame photometry is the analysis method to determine the type
and/or concentration of certain metal ions from the spectra they
produce when exposed to a flame.
• Metallic salts in solution are sprayed as aerosol in a high
temperature flame source to be vaporized.
• These metallic salts include sodium, potassium, calcium, lithium
etc.
• The atoms in the vapor, excited by the flame, release radiation
which has the wavelength specific for different types of metals.
• To estimate concentration of certain ions, the intensity of
wavelength is measured.

3. The picture below describes how does a flame photometry analysis
work……

4. • The machine used to carry out flame photometry analysis is known as
Photoelectric Flame Photometer.
• Some renowned manufacturers are Kruss, Genway, Spectrolab etc.

5. History & Development
• German metallurgist Georgius Agricola in his 1556s
paper, commented on how to identify different metallic
contents of an ore from the ‘colour of fumes’.
• This was a qualitative analysis method to identify ore
contents.

6. History & Development
• Sir John Frederick William Herschel (1823) published emission
spectra of an alcohol lamp after studying.
• This was the first example of a lamp being studied for emission.

7. History & Development
• Jean Bernard Leon Foucault (1849) linked sodium
emission of a lamp with that of sun.
• Kirchhoff & Bunsen (1859) developed first
spectroscope hence beginning the trends in
analytical spectroscopy and discovered rubidium
and caesium in 1960.s
• These events were followed by discovery of
elements like indium, gallium, thallium etc. Janssen

8. History & Development
• Pierre Jules Cesar Janssen (1870) stated quantitative
estimation of sodium.
• He used lamp as flame source and introduced ore to
the flame on a platinum wire.les César Janssen
• Champion, Pellet and Grenier (1873) measured
sodium emission with the help of spectroscope with
aid of visual photometry. They used two flames
each for unknown and standard samples.kn
• This was the invention of flame photometer as we
see it today.o

9. History & Development
• Louis Georges Gouy (1877) designed a pneumatic
atomizer to inject a controlled amount of sample
into the flame.
• The result was increased precision and accuracy of
analysis.an
• H. Lundegårdh and T. Philipson (1938) used an air-
acetylene burner for developing an entire system of
flame excitation.
• it produced a higher flame temperature while
holding the flame excitation stability.

10. History & Development
• Barnes et al. (1945) made first flame photometer
consisting modern flame cell (Meeker air- natural
gas burner), in United States of America.

11. History & Development
• Beckman Corporation (1948) introduced DU
spectrophotometer attached with flame aspirator. a
• A. Walsh (1955) laid down the foundation of atomic
absorption analysis.

12. History & Development

13. Principle of
Flame Photometry
• At the temperature of flame the metal salts get
thermally dissociated into atoms.
• During this process the atoms get excited and
move from ground state (GS) to excited state
(ES).
• When these excited atoms returns to the
ground state, radiation of specific wavelength is
emitted from these excited atoms.

14. Principle of
Flame Photometry
• This wavelength is specific to individual element.
• This specific wavelength is isolated by an optical fibre
and then photodetector converts it into electrical
signal.
• The intensity of the emitted wavelength is
proportional to the concentration of element
present and the number of atoms moving back to
ground state from excited state is proportional to
number of atoms excited i. e. the concentration of
sample.

15. Calculations
• The emitted radiation is calculated by the following equation:
E2 - E1 = hν
Where, E2 is excited state energy
E1 is ground state energy
h is Planck’s constant
ν is the emitted radiation
ν is the ratio of C (speed of wave) and λ (wavelength).
Hence, ν = C/λ, Hence, E2 - E1 = hC/λ, Hence, λ = hC/E2 - E1
• This way, we can calculate the wavelength (λ).

16. Boltzmann Distribution
• The fraction of free atom that are thermally exited is governed by a
Boltzmann Distribution.
N* / N = Ae–∆E/kT
• N* =is the number of exited atom
• N = is the number of atom remaining
• in the ground state
• AE = is the difference in energies levels
• k = The Boltzmann constant
• T = the temperature

17. Scheibe-Lomakin Equation
• The intensity of emitted light is calculated by Scheibe-
Lomakin equation.
• The equation is as follows: I = k * cn
Where, I is intensity of light
k is the constant of proportionality
c is the concentration of element
n ~ 1 (at the linear part of calibration curve)
• Hence, intensity of light is directly proportional to the
concentration of sample.

18. Components of a modern
Flame Photometer
1. Burner
2. Nebulizer and mixing
chamber
3. Mirrors and Slits
4. Monochromator
5. Detector
6. Recorder and display unit

19. Components of a modern
Flame Photometer
Nebulizer
+
Burner
Mirror and Slits
+
Monochromator
Detector
(Photomultiplier
tube etc.)
Recorder and
Display
Fuel + Oxidant
Sample
Sample Delivery Unit Selection Unit Read-out Unit
• Notably, not all sample delivery system/unit consists of nebulizers.
• Some other types are:
 Direct insertion (solid powder)
 Laser ablation (solid metal)
 Spark or arc ablation (conducting solid)
 Glow discharge sputtering (conducting solid)

20. 2. Nebulizer and mixing chamber
• Nebulization is turning the sample solution in an aerosol by jet of
highly compressed gas.
• Function is to transport the aerosol to the flame at a steady rate.
• In mixing chamber, fuels and oxidants are mixed together then
transported to the flame.
Design of a nebulizer

21. 2. Nebulizer and mixing chamber
• Different types of nebulizers are:
 Pneumatic nebulizer
 Ultrasonic nebulizer
 Electro thermal vaporizer
Pneumatic and ultrasonic nebulizers Electro thermal vaporizer

22. 1. Burner
• The burner provides the flame.
• Flame contains many zones based on differences in temperature.
• A composition of fuel and oxidant is used to get the desired set up.
Different combinations of fuel and oxidant

23. 1. Burner
• Different types of burners are:
a. Mecker burner
b. Laminar flow burner
c. Total consumption burner
d. Lundegårdh burner
e. Shielded burner
a
e
d
c
b

24. 3. Mirror and Slits
• A mirror is located behind the burner to reflect the radiation back to the slits of
monochromator.
• The reflecting surface of the mirror is front faced.
• The slits allow a certain amount of radiation to get into monochromator.
• The two slits are entrance and exit slit.

25. 4. Monochromator
• Used to select the light of a specific wavelength from the flame.
• Filter wheel having a filter for each element is used.
• For analyzing an element its specific filter is used as it will filter all
other non-specific wavelengths.
Some elements with their respective flame colour and wavelength

26. 4. Monochromator
• Monochromator types are:
a. Prism monochromator
b. Grating monochromator
a
b

27. 5. Detector
• Three types of detectors are:
a. Photomultiplier tube
b. Photo emissive cell
c. Photo voltaic cell

28. 6. Recorder and Display
• Recorder records the data obtained from the detector.
• Display unit aka Read-out unit displays this data.
• Also consists electronic devices of amplifying and electrical
apparatus for measuring and direct recording.
Front panel of a photoelectric flame photometer

29. Calibration Curve of a
Flame Photometer
• In flame photometry, Scheibe-Lomakin equation says that emitted light
intensity from the flame is directly proportional to the concentration
of the species being aspirated.
• The graph below shows that the direct relationship between the
emission and concentration is true only at relatively low
concentrations of mg/L level (up to 50 mg/L).
• The curve in the graph is known as calibration curve which is obtained
by using standard solutions containing known concentrations of the
elements to be determined.
• It is important to emphasize that each element has its own
characteristic curve and separate curves must be constructed.

30. Calibration Curve of a
Flame Photometer
• The concentration range covered by the calibration curve depends
on the expected concentration so that the sample readings fall
somewhere inside the calibration curve.
• Once the calibration curve has been plotted, the scale reading for
the sample solution is compared with the curve to find the
concentration.

31. Applications
• It is used for qualitative analysis of elements by comparing emitted
wavelength with the standard.
• It is used in quantitative analysis for determining the concentration
of I and II group elements.
• It is used for examine hard water for determining the concentration
of calcium present in it.
• It is used for examine urine for determining the concentration of
sodium and potassium present in it.
• It is used for examine hard biogas and ceramic materials for
determining the concentration of calcium present in it.

32. Limitations
• Only few elements can be analyzed.
• Many metallic salts, soil and other compounds are insoluble in
common solvent, therefore these compounds cannot be examined
by flame photometry as sample only can be introduced as a
solution into the flame.
• Amount of sample is very important because small amount of
sample are tough to examine as samples are volatized (sample is
lost during volatization).
• In process of solubilisation of samples with solvent, there are
chances of mixing of impurities with sample which leads to error in
the observed spectra.

33. Assistance
• https://en.wikipedia.org/wiki/Photoelectric_flame_photometer
• Forensic Science: Paper no 4: Instrumental Methods & Analysis. Module no. 24: Flame
Photometric Analysis.
• https://nitsri.ac.in/Department/Civil%20Engineering/CWE-
301_WATER_QUALITY_AND_ENVIRONMENT_Flame_Photometry.pdf
• Photos - Google