The First Method Of Aas

1922 WordsApr 5, 20178 Pages
The first method to talk about is AAS. The general idea of AAS is to make up standard solutions of differing amounts of known concentrations of each of the metals to generate a calibration curve and then measure the absorption or emission of the unknown solution and then compare that value against the concentration curve to figure out the concentration of each metal in the sample. Atoms are put into the gas phrase for analysis. The process of getting the metal into the gas phase involves adding energy to the sample. First, water is driven off and then molecules are broken apart into atoms. If more energy is added, the atoms go from their ground state into their electronically excited state. When performing atomic absorption spectroscophy,…show more content…
[Leverman] Intensity is measured as log I0/I where I0 is the intensity of the blank and I is the intensity of the analyte. The light source shines specific wavelengths of light through the flame that then hit the detector. Because specific wavelengths of light are absorbed by the sample, what actually reaches the detector is a portion of what was emitted by the source in atomic absorption spectroscopy. The source and the sample are matched in such a way that the chemical composition of the filament within the lamp contain some of the same types of atoms that is analyzed. In this specific case, the filament would be made of copper and lead and perhaps some other metals. The source emits several lines where each line corresponds to a different energy transition between the ground and excited state and the sample absorbs only a fraction of that energy. There is a lot of electromagnetic spectrum information heading towards the detector so the purpose of the monochromator, which is located between the sample and the detector, is to sort out that light information spatially similar to what a prism does when white light sunlight hits it and produces a rainbow. The instrument acts like all other absorption instruments in that, as the concentration of atoms increases, the light intensity hitting the detector goes down and conversely as the number of atoms decrease the light
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