mohd wahid (aes)
TRANSCRIPT
ATOMIC EMISSION SPECTROSCOPY
COUSE TITILE: ADVANCE ANALYTICAL TECHNIQUES - 1COURSE CODE: ICM 1002GROUP NO: 01 NAME – MOHD WAHID ROLL NO-2016-ICM-04 ENROLL NO-GD 9740
INTRODUCTION• Used as standard method for the metal
analysis• In atomic emission small part of sample
is vaporized from free atom that attain energy from excitation source results in transition from lower to higher energy state on returning back emit a photon of radiation
PRINCIPLE OF ATOMIC EMISSION
SPECTROSCOPYAND
SCHEMATIC DIAGRAM OF INSTRUMENTATION
Principle
• The electrons of an atom moves from higher energy level to lower energy level, they emit extra amount of energy in the form of light which is consist of photons.
Instrumentation
Comprises on:• Source & Sample• Atomizer• Monochromator• Detector & readout device
Schematic Diagram Of Instrumentation
COMPONENTS1. Light source
a. Inductively coupled plasma (ICP)b. Direct current plasma (DCP)c. Flamed. Arc and spark
Plasma Source
“ Plasma is defined as a neutral gas containing significant number of both
positive and negative ions or free electrons”
Mechanism Of Inductively Coupled Plasma
• The inductively coupled plasma torch consist of 3 concentric silica quartz tube.
• Argon stream that carries the sample in the form of an aerosol, passes through the central tube.
• Plasma is initiated by a spark from a tesla coil. Argon gas ionized and emission is measured.
Laser Induced Plasma• In this source highly energetic laser pulse
used to generated optical sample excitation.• When laser beam focused on the small spot
on a sample(liquid, solid and gases).• The temperature of heated region is rise
rapidly that vaporized the sample material & induced plasma formed .
• vaporized material excited & emit radiation.
Laser Beam Excitation
Microwave Induced Plasma
• Used for multi-analytic determination of major to minor elements.
• Employed microwave energy to produced plasma.
• MIP generated from few hundred watts of radiation source
• Atomized sample pass through plasma & promote electron excitation .
ATOMIZERAND
SAMPLE HANDLING
Atomizer
• Elements to be analyzed needs to be in
atomic state.
• Atomization; Conversion of sample (maybe;
solid or liquid) into free gaseous atom.
• Atomizer; Device used for atomization
TYPES OF ATOMIZER
FLAME ATOMIZER
CONTINUOUS
DISCRETE
ELECTRO-THERMAL ATOMIZER
1. Flame Atomizer
• To produce flame, required oxidant gas and flame gas.
• Mostly the air-acetylene flame or nitrous oxide- acetylene flame is used.
• Liquid or dissolved samples are typically used with flame atomizer.
Flame Atomization
2. Electro-thermal Atomizer
• Also known as “Graphite Furnace Atomizer”
• More convenient to uses a non-flame method i.e. electrically heated graphite tube.
Atomization Of Sample
DRYING
• drying of sample into solid deposit.
• by heating graphite tube at 110 ºC.
ASHING
• conversion of organic matter in CO2 and H2O &volatilization of inorganic matter.
• by heating graphite tube at 350-1200 ºC.
ATOMIZATION
• leads to gaseous atom
• by raising the temperature up to 2000-3000 ºC.
Sample Handling
• The droplets of sample introduced in atomizer should be of constant size.• The temperature should be maintained to
obtain good reproducibility.• The speed of introducing sample must be
equal to certain permissible band values.• Sufficient sample volume should be
available for maximum efficiency
Monochromator
• It is a device use to transmit narrow band of wavelength which is chosen from wavelength of wider range available.
• Types of monochromator:• Prism Monochromator• Grating Monochromator
DETECTORS
Phototube (Photo Electric Cell)
• Glass filled or vacuum tube
• Sensitive to light
• Depend on frequency and intensity of incoming photon
• Need amplifier. But are replaced by photomultiplier detectors.
Photo Multiplier Detector
• Vacuum phototubes, are extremely sensitive detectors of light in the ultra violet, visible, and near-infrared region ranges of the electromagnetic spectrum.
APPLICATION
Applications
• It is used for rapid analysis of multi-component pharmaceutical tablet.
• It is used for elemental analysis.
• It is used primarily for the identification and determination of metals in traces amount.
• It is used for determination of mineral composition of igeous and metamorphic rock.
• It is used for routine analysis of wear metals in lubricating oils.
• It is used for the analysis of sodium, potassium and lithium.
CONCLUSION
The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of electromagnetic radiation emitted due to an atom or molecule making a transition from a high energy state to a lower energy state. The photon energy of the emitted photon is equal to the energy difference between the two states. There are many possible electron transitions for each atom, and each transition has a specific energy difference. This collection of different transitions, leading to different radiated wavelengths, make up an emission spectrum. Each element's emission spectrum is unique. Therefore, spectroscopy can be used to identify the elements in matter of unknown composition. Similarly, the emission spectra of molecules can be used in chemical analysis of substances.
REFFERENCES1. Principals of Instrumental Analysis, D.A.Skoog, F.J.Holler, T.A Nieman, Vth edn,
Thomson Brooks/Cole,1998.2. Instrumental methods of Chemical analysis, G.W.Ewing, Vth edn, Mc-Graw Hill
Book Co, New Delhi, 1985.