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Search inside document. Atomic Spectroscopy Ashraf M. Flame Photometry The nebulizer-burner system To convert the test sample into gaseous atoms Nebulizer produce an aerosol of the test solution Burner in which the mixing between fuel and oxidant Types of burner system Flame 1.
Pre-mix or laminar flow burner Fuel in Advantages 1. Total consumption burner Fuel Advantages 1. Free from explosion hazards Disadvantages 1.
Sample preparation: of max. It is very important to obtain the sample in a form of solution, where the spectral and chemical interferences are absent b.
Water and very pure reagents are to be used because of the high sensitivity of the technique c. Deviations from linearity may occur Absorbance, Intensity 3. Atomic Absorption Spectroscopy Atomic Absorption spectroscopy involves the study of the absorption of radiant energy by neutral ground state atoms in the gaseous state.
Formation of stable compounds: incomplete dissociation of the sample in flame 2. Formation of refractory oxides: which fail to dissociate into the constituent atoms Examples 1. Solvent extraction of the sample or of the interferring elements Ionization Interferences Ionization of atoms in the flame decrease the absorption or emission Overcome : 1.
Variation in gas flow rate 2. Variation in sample viscosity 3. Change in flame temp. Overcome: 1. Disadvantages of AAS: Hollow cathode lamp for each element. Expensive element. Measures the radiation absorbed by the unexcited atoms 1. Measures the radiation emitted by the excited atoms 2. Depends only on the number of unexcited atoms 2. Depends only on the number of excited atoms 3.
Absorption intensity is NOT affected by the temperature of the flame 3. There is no single elements excitation source can excite all 2. Relatively rapid technique Disadvantages 1. Atomic Emission Spectroscopy Advantages of plasma excitation source: The sample could be introduced in solution form through a nebulizer easy for quantitative analysis. It is suitable for quantitative multielement determinations 3- The high temperature of plasma eleminates many chemical interferences present in a flame 4- It is well suited for refractory oxide forming elements e.
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Introduction: Atomic emission spectroscopy AES or OES uses quantitative measurement of the optical emission from excited atoms to determine analyte concentration. Inductively coupled plasma atomic emission spectroscopy ICP-AES , also referred to as inductively coupled plasma optical emission spectrometry ICP-OES - is a type of emission spectroscopy that uses the inductively coupled plasma to produce excited atoms and ions that emit electromagnetic radiation at wavelengths characteristic of a particular element.
Sample solution containing elements Formation of liquid droplets atomization excitation Emission of Radiation at a Specific Wave Length Measure the intensity of emitted radiation 4. It is reflected off a collimating mirror on to a diffracting grating.
As the grating rotates the light separates into its different spectral components,and passes the desired wavelength to the second collimating mirror. The monochromatic light focuses on to exit slit positioned in front of the detector.
PMT is to convert optical rotation photons into an electrical signal electrons. It consists of a vaccum photocell with an anode, photocathode and a number of dynodes which have an increasingly positive potential with respect to the photocathode. MalikSafi2 Jan. Taylor, S. Branch, H. Crews, D. Halls and M. White, J. Yamamoto, T.
Kumamaru, Y. Hayashi and M. Kanke, Talanta, 19 Muhlbaler, C. Stevens, D. Graczyk and T. Tisue, Anal. Kumamaru, H. Matsuo, Y. Okamoto and M. Ikeda, Anal. Acta, Yin, G. Schlemmer and B. Welz, Anal. Lynch and D. Littlejohn, Talanta, 37 Department [I31 Y. Ma, J. Bai, J. Wang, Z. Li, L. Zhu, Y. Li, H. Zheng and of Commerce were employed to evaluate the validity B. Li, J. The samples were dissolved [ E. Lueker, J. Meuthen and W. For the de- Ml S. Tao, Y. Shijo, L.
Wu and L. Lin, Analyst, Cache, I. Beltran and C. Nerin, J. After Valdes-Hevia y Temprano, M. Sanz-Medel, J. Concentric nebuliser. Babington nebuliser: The principle involved in the liquid to flow over a smooth surface with a small hole in it.
High-speed argon gas from the hole shears the sheet of liquid into small drops. This is very sensitive nebuliser. Babington nebuliser. Pumps: These are mainly used to introduce the samples into the nebuliser. Commonly the peristaltic pumps are employed. These are composed of the rollers which pushes the sample solution through the tube.
This process is known as the peristalsis. Peristaltic pump diagram. Spray chambers: The spray chamber is used to transport the aerosol into plasma which is placed between the nebuliser and torch. This also helps in the removal of the large droplets. These must be made up of corrosion-resistant material. Spray chamber diagram. Drains: This is mainly used to drain the sample from the spray chamber to waste container.
Torch: This is mainly used to produce the plasma. This contains the three concentric tubes for argon gas flow and the sample aerosol injection.
The gas flow carries the sample aerosol injected into the plasma through the sample injector tube. Torch or plasma source diagram. RF generator: This is mainly used for the generation and sustainment of the plasma discharge. It ranges from the to watts. The commonly used RF generators are the following:. Crystal controlled generators: This consists of the piezoelectric quartz crystal to produce an RF oscillating signal. Free running generators: This operates at an oscillation frequency.
Detectors: The photomultiplier tubes are generally employed as the detectors. The principle involved in the detector is the secondary emission of the electrons when the light falls on the cathode and the replication of the anodes. The secondary emission of the electrons produces the current signals. Photomultiplier tube detector diagram.
High resolution. Low stray light. Wide dynamic range.
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