Atomic Absorption Spectroscopy/Atomic Absorption Spectrometry/AAS скачать в хорошем качестве

Atomic Absorption Spectroscopy/Atomic Absorption Spectrometry/AAS

This video describes the principle, instrumentation and working of Atomic Absorption Spectroscopy/Atomic Absorption Spectrometry/AAS. The various sources used in AAS is listed . It explains the source, flame atomiser, monochromator, detector and the recorder. and it's role. It lists out the various applications of AAS. It also describes how too determine the unknown concentration of the sample such as nickel(Ni) using the calibration graph. Atomic Absorption Spectroscopy/ Atomic Absorption Spectrometry (AAS) You will be able to elucidate the principle of atomic absorption spectroscopy. explain the instrumentation and working of atomic absorption spectroscopy. list out the applications of atomic absorption spectroscopy. compare flame photometry with atomic absorption spectroscopy. Absorption of light of its own characteristic wavelength by atomised metal when irradiated with electromagnetic radiation and the correlation of its absorbance with the concentration of the metal is atomic absorption spectroscopy/atomic absorption spectrometry. Used to detect metals and metalloids Nebuliser converts liquid solution to fine particles of aerosol/mist Solvent gets vapourised leaving behind the solid residue. The solid residue gets vapourised due to high temperature of the flame and the molecules dissociate to atoms. The metal atoms absorbs light of its own characteristic wavelength when irradiated with electromagnetic radiation. (Ni- 393nm, Cu- 325nm Na- 589nm, Li 670nm, Ca 622 nm, Ba-554nm) Radiation source – Source of light with varying wavelength range depending on the type of source used. Hollow cathode lamp, deuterium lamp, xenon lamp (continuum sources), electrode less discharge lamps. Burner– Air and fuel combines in the burner to produce the flame. Nebuliser and mixing chamber – Converts the liquid sample to mist and sprays the fine particles into the flame using the compressed jet of gases (fuel and air). Atomiser – Converts the analyte molecules to gaseous atoms. Flame atomiser, electrothermal atomiser, hydride atomiser, glow discharge atomiser, cold-vapour atomiser. Monochromator/Filter – Allows only the chosen wavelength and absorbs all the other wavelengths. e.g. prism, diffraction grating etc. Detector – It detects the intensity of the light and generates current proportional to it. eg. Photocell/photodiode. Amplifier - the current signal is amplified and sent to the data processor. Data processor and display - It displays the absorbance values and processes to provide relevant data. The wavelength is fixed at 393 nm using the monochromator. The calibration graph is plotted with the concentration against absorbance. The sample of unknown concentration (Cu) is placed in the same cell and the absorbance value (Au) is noted. From the calibration graph the unknown concentration (Cu) can be found . The blank sample is sprayed over the flame and the absorbance is set to zero. Now the series of standard NiCl2 samples of known concentrations are sprayed one by one and the absorbance values are noted. Applications of Atomic absorption spectroscopy Presence of metals in water and waste water such as As, Cd, Hg, Pb, Ca, Mg etc. can be determined. Contamination of metals in food cereals, milk etc. Presence of certain metals in shampoos, wash liquids etc. Presence of metals in biological fluids in blood, urine, saliva, brain tissue, muscle tissue, bones, plasma, liver etc. Presence of metals in metallurgical products, alloys, industrial plating baths etc.. Analysis of metals present in soils, sediments and rocks.