Atomic Absorption
INTRODUCTION: In atomic spectroscopy the samples are vaporized at 2000-8000k. The process of this involves two steps , one is atomization of sample and the other is absorption of light radiation from light source. The atoms in the vapour are measured by absorption or emission at characteristic wave lengths. The main usage of this was to detect one element from another in the complex sample which has taken ie., it has ability to perform multiple element analyses. Absorbance should obey Beer’s law ie., Analyte is measured in diluted concentrations from parts per million level to parts per trillion level and the monochromatic light radiation. There are types of spectroscopy according to the measurements we do they are. 1. Atomic absorption: Atoms from ground state to the excited state are measured. 2. Atomic emission: Atoms from excited state fall to the ground state are measured. 3. Atomic flourescence : atoms from excited electronic state fluoresce to ground state.
In atomic spectroscopy the analyte is analyzed by using flame, graphite furnace and a plasma. In this experiment we are dealing with flame and plasma to measure absorption and emission.
Atomic absorption spectroscopy: This is done by using Flames and Hollow cathode lamp. The method is to introduce the sample in to the flame as a fine spray by adjusting the flow of fuel and oxidant. The sample is vaporized in to atoms and these atoms absorb the light from the Hollow cathode lamp. The wavelengths are adjusted to particular elements which we analyze from the complex sample, so there is no interference with measurement and this gives us both sensitivity and selectivity of elements. To reduce the back ground interference the wavelength of interest is isolated by the monochromator placed between the sample and detector. Now let us go in to detail about Flames and Hollow cathode lamp how it works.
Flames: Most of the atomic absorption spectrometers use burner for the
In atomic spectroscopy the analyte is analyzed by using flame, graphite furnace and a plasma. In this experiment we are dealing with flame and plasma to measure absorption and emission.
Atomic absorption spectroscopy: This is done by using Flames and Hollow cathode lamp. The method is to introduce the sample in to the flame as a fine spray by adjusting the flow of fuel and oxidant. The sample is vaporized in to atoms and these atoms absorb the light from the Hollow cathode lamp. The wavelengths are adjusted to particular elements which we analyze from the complex sample, so there is no interference with measurement and this gives us both sensitivity and selectivity of elements. To reduce the back ground interference the wavelength of interest is isolated by the monochromator placed between the sample and detector. Now let us go in to detail about Flames and Hollow cathode lamp how it works.
Flames: Most of the atomic absorption spectrometers use burner for the
References: 1. http://www.cee.vt.edu/ewr/environmental/teach/smprimer/aa/aa.html 2. http://weather.nmsu.edu/teaching_material/soil698/student_reports/spectroscopy/report.htm 3. http://www.docstoc.com/docs/24254489/ATOMIC-ABSORPTION-SPECTROPHOTOMETRY-COOKBOOK_1_ 4. http://www.epa.gov/osw/hazard/testmethods/sw846/pdfs/7000b.pdf 5. http://books.google.com/books?id=JM-R91MDsiEC&pg=PA430&lpg=PA430&dq=ionization+interference+in+aas&source=bl&ots=3gGbUn-AY2&sig=z0dEvS0HghYpJs_akYE_ClpZeVM&hl=en&ei=pwd9TZWfGsnJsgaRkL3tBw&sa=X&oi=book_result&ct=result&resnum=9&ved=0CEsQ6AEwCA#v=onepage&q=ionization%20interference%20in%20aas&f=false