Flame Emission Spectroscopy

1. Flame Emission
Spectroscopy
Presented By:
Lok Raj Bhandari
Asst. Professor
M.Pharma,MBA
KU

2. Introduction
• FES is a method of chemical analysis that uses intensity of light
emitted from flame,arc or spark at particular wavelength to determine
quantity of elements in a sample.
• In FES, atoms and molecules that are excited to high energy level can
decay to lower energy level by emitting radiations.
• The substantance 1st absorb energy then emits energy in the form of
light.

3. Principle
• Atomic Emission Spectroscopy is a process in which the light emitted
by excited atoms or ions is measured.
• The emission occurs when sufficient thermal energy is supplied by
plasma to excite a free atom or ion to an unstable energy state. Light
is emitted when the atom or ion returns to a more stable
configuration or the ground state.
• The wavelengths of light emitted are specific to the elements which
are present in the sample and intensity of emitted light is dependent
on their concentration

4. • When a substance is heated to a high temperature, the atoms in the
vapors get energized.
• These energized atoms then return to the ground state by emitting
electromagnetic radiations of certain definite wavelength.
• A series of bright lines separated from each other by dark spaces is
obtained and this is called atomic emission spectra.

5. • When an electron jumps from a higher energy level E2 to a lower
energy level E1 , the difference in energy of the energy levels i.e. E2 –
E1 = ΔE = hν = h c/λ, is released in the form of a spectral line of
frequency ν = c/λ = ΔE /(h) .
where c is the speed of the light and h is the planck’s constant .
• Emission spectra are produced by substances which give light while
burning.

6. • The working principle of atomic emission spectroscopy involves the
examination of the wavelengths of photons discharged by atoms and
molecules as they transit from a high energy state to a low energy
state.
• A characteristic set of wavelengths is emitted by each element or
substance which depends on its electronic structure.
• A study of these wavelengths can reveal the elemental structure of
the sample.

8. Instrumentation
• Instrumentation for atomic emission spectroscopy is similar in design to that
used for atomic absorption.
• In fact, most flame atomic absorption spectrometers are easily adapted for
use as flame atomic emission spectrometers by turning off the hollow
cathode lamp and monitoring the difference between the intensity of
radiation emitted when aspirating the sample and that emitted when
aspirating a blank.
• Many atomic emission spectrometers, however, are dedicated instruments
designed to take advantage of features unique to atomic emission, including
the use of plasmas, arcs, sparks, and lasers, as atomization and excitation
sources and have an enhanced capability for multielemental analysis.

9. FES vs AAS

10. Instrumentation

11. Instrumentation
1. Atomizer/Nebulizer
2. Burner
3. Fuel and Oxidants
4. Monochromators
5. Detectors

12. 1. Atomizer
• The process of converting a sample to fine mist of finely divided
droplets using a jet of compressed gases.
Types:
a) Pneumatic nebulizer
b) Electro thermal Vaporizer
c) Ultrasound nebulizer

13. 2. Burner
• Burner is used to spary the sample solution into fine droplets mix with
fuel and oxidants. So on the homogenous fkame of stable intensity is
obtained.
Types of Burner:
a) Total consumption burner
b) Laminar flow burner
c) Mecker burner
d) Shielded burner

14. 3.Fuel and Oxidants
• Ideal combination of oxidant and fuel which gives the desired
temperature in the emission spectroscopy.

15. 4. Monochromator
• They disperse radiation coming from the flame and falling on it.
• Dispersed radiation goes to detector from exit slit.
• Monochromators are more efficient than filters in converting a polychromatic
light to monochromator light
• It consists of following
• a) Entrance slit ( to get narrow source)
• b) Collimator ( to render light parallel)
• c) Gratings or prisms ( to disperse radiations)
• d)Collimator ( to reform the image of entrance slit)
• e) Exit slit ( to fall on the sample cell)

16. 5. Detectors
• When a radiation is passed through a sample cell, part of its being
absorbed vu the sample solution and rest is being transmitted.
• The transmitted radiation falls on the detectors and the intensity of
absorbed radiation can be determined.
• Detectors convert the light signal into electrical signal which can be
read or recorded.
• Types
a) Barrier layer cell or photo voltaic cell
b) Photo multiplier tubes

17. Applications
• It is used to detect elements of group I and II of periodic table.The elements
are Na, Li, Mg, Ca, Ba.
• Concentration of sample can be detected by this method.
• Determination of purity in food and drinks
• Soils, Crude oils, petroleum products, plastic analysis.
• Determination of pollution of water by metals.
• Analysis of geochemical exploration for minerals.
• Similarly, in biology, the ICP-AES technology can evaluate aluminum from
blood, copper from brain tissue, selenium from the liver, and salt from
breast milk.

18. • Inductively coupled plasma atomic emission spectroscopy can detect
metal traces such as calcium (Ca), copper (Cu), iron (Fe), manganese
(Mn), magnesium (Mg), phosphorus (P), potassium (K), and zinc (Zn)
in beer or wine.
• The quantities of Na+ and K+ ions in the human body are critical for
performing numerous metabolic tasks. The quantities of these
substances can be measured by diluting and aspirating a blood serum
sample into the flame.
• AES is used to determine calcium and magnesium in cement.
• AES is used to determine lead in gasoline.
• Ca, Mg, Na, and K levels in blood serum and plasma were analyzed by
using AES.
• AES is an effective method for detecting metallic toxins.

19. Advantages
1. It is a sensitive method capable of detecting concentrations as low as 1
ppm.
2. The analysis requires a small sample.
3. If proper comparison standards are provided, working time is reduced.
4. There is no need to prepare the sample.
5. Solid and liquid samples are easily examined.

20. Disadvantages
1. It only applies to metals and metalloids. Nonmetals cannot be
examined.
2. The instrument is quite expensive.
3. It is a destructive procedure that results in the destruction of the
sample.
4. Concentrated solutions are undetectable.