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Atomic absorption spectroscopy (AAS) determines the presence of metals in liquid samples and measures their concentrations. In their elemental form, metals will absorb ultraviolet light when they are excited by heat. Each metal has a characteristic wavelength that will be absorbed. The AAS instrument looks for a particular metal by focusing a beam of UV light at a specific wavelength through a flame and into a detector. The sample of interest is aspirated into the flame. If that metal is present in the sample, it will absorb some of the light, thus reducing its intensity. The instrument measures this change in intensity and a computer data system converts the change in intensity into an absorbance. As concentration goes up, absorbance also goes up. By understanding these relationships, scientists can construct a calibration curve by running standards of various concentrations on the AAS and observing the absorbances. |
