Atomic absorption spectroscopy identifies minerals or metals in liquids or solids by measuring the absorption of light directed at the sample. The technique can detect traces and any element, with iron, aluminum, copper, and lead being the most common. Flame and furnace methods use different heating methods, and calibration is necessary for accuracy. The technique has various applications, including detecting mercury in water and lead in paints.
Atomic absorption spectroscopy is a technique used to identify which minerals or metals are present in a liquid or solid. A light source is directed at the sample and the absorption of that light is measured and compared to known absorption spectra of various metals. Each element has a unique spectrum that appears when heated or when it absorbs light.
The amount of metal or mineral in the sample does not matter when using atomic absorption spectroscopy. Traces can also be identified using this method. The more metal in the sample, the more absorption will be detected. The most common metals identified with this method are iron, aluminum, copper and lead, but any element can be identified.
In flame atomic absorption spectroscopy, the machine is made up of several parts. The desired wavelength of light comes from a hollow cathode lamp shining directly on the sample. A nebulizer takes the liquid sample and creates a mist which is blown into a flame. The heat of the flame releases the individual elements which then absorb the light. Next, a monochromator filters out unwanted spectral lines and a photomultiplier determines the amount of absorption that occurs.
By using several hollow cathode lamps with various wavelengths of light, atomic absorption spectroscopy can identify multiple elements at the same time. In this case, they would be isolated in the monochromator and the photomultiplier would show the amount of absorption for each wavelength.
Furnace atomic absorption spectroscopy is similar to flame atomic absorption spectroscopy. Instead of spraying the sample into an open flame, a drop of the sample is heated inside a graphite furnace. The furnace is heated by an electric current and is insulated from a gas, usually argon.
When performing atomic absorption spectroscopy, it must be ensured that the beam of the hollow cathode lamp is directly aligned with the sample. If the beam is not aimed at the sample, absorption numbers will not be accurate and sample components may not be detected. Calibrating the machine before using the actual sample can avoid this problem.
There are several applications of atomic absorption spectroscopy. It is often used to determine minerals and metals, such as mercury, in water samples. It can also be used to detect the presence of lead in everyday products, such as paints.
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