What is the basic principle of atomic absorption spectroscopy?

What is the basic principle of atomic absorption spectroscopy?

It uses the principle that atoms (and ions) can absorb light at a specific, unique wavelength. When this specific wavelength of light is provided, the energy (light) is absorbed by the atom. Electrons in the atom move from the ground state to an excited state.

What are the components of AAS?

The standard AAS instrument consists of four components: the sample introduction area, the light (radiation) source, the monochromator or polychromator, and the detector (figure 1).

What can be detected using atomic absorption spectroscopy?

AAS is an analytical technique used to determine the concentration of metal atoms/ions in a sample. Metals make up around 75% of the earth’s chemical elements. In some cases, metal content in a material is desirable, but metals can also be contaminants (poisons).

What causes an atomic absorption spectrum?

An absorption spectrum occurs when light passes through a cold, dilute gas and atoms in the gas absorb at characteristic frequencies; since the re-emitted light is unlikely to be emitted in the same direction as the absorbed photon, this gives rise to dark lines (absence of light) in the spectrum.

What type of result can AAS produce?

AAS provides a high degree of accuracy. Normally results fall within a range of 0.5 per cent to 5 per cent accuracy, but this may improve further depending on the standards set for testing and analysis. It is a highly sensitive method of analysis. In a given material, it can measure parts per billion of a gram.

What are atomic spectroscopy used for?

Analytical methods of atomic spectroscopy have been used for elemental analysis identification, and quantitation in varieties of samples. Recently, most all of the spectroscopic techniques available are used in the analysis of metals and trace elements in samples of industrial and environmental origin.

Which gases are used in AAS?

Typical gases used in AAS are Nitrogen and Argon.

What is chemical interference in AAS?

Chemical interferences. Chemical interference occurs when an analyte is not totally decomposed in flame. There is less atoms present, and therefore a reduced absorbance of the analyte. Compound Formation. Compounds cannot be broken down in flame.

What is monochromator in AAS?

The monochromator is included as an important device of the optical system of an atomic absorption spectrophotometer. The function of this device in atomic absorption is to separate the spectral line of interest from others spectral lines with different wavelengths emitted by the hollow-cathode lamp.

Why is atomic absorption spectroscopy important?

Using an atomic absorption spectrometer, you can determine the concentration of many different elements in a sample. The spectrometer identifies the amount of metal in liquids and measures the quality of metal in a sample as well.

What is atomic spectroscopy example?

An example of this is laser ablation inductively-coupled plasma atomic emission spectrometry, where a laser is used to vaporize a solid sample and an inductively-coupled plasma is used to atomize the vapor.

Why acetylene gas is used in AAS?

The type of flame most frequently used in flame AAS is the acetylene/air flame (2200–2400 °C). In the case of heat-resistant, oxide-forming elements, such as Al, Si, V, Ti, an acetylene/nitrous oxide flame (2600–2800 °C) provides a more favorable chemical, thermal and optical environment.

What is atomic absorption spectroscopy?

Atomic absorption spectroscopy is an alternative technique that measures the light absorbed by ions during electronic excitation in a flame.

What are the limitations of atomic spectroscopy in the field of Science?

Third, any contaminant associated with the specimen will be digested along with it, and will contribute to the results. Fourth, although atomic spectroscopic techniques do have very low limits of detection, they are often not low enough to detect trace elements in trace evidence.

Who is the author of atomic absorption spectrometry?

B. Welz, M. Sperling (1999), Atomic Absorption Spectrometry, Wiley-VCH, Weinheim, Germany, ISBN 3-527-28571-7. A. Walsh (1955), The application of atomic absorption spectra to chemical analysis, Spectrochim. Acta 7: 108–117. J.A.C. Broekaert (1998), Analytical Atomic Spectrometry with Flames and Plasmas, 3rd Edition, Wiley-VCH, Weinheim, Germany.

What is the resolution of an atomic absorption line?

The resolution has to be equal to or better than the half width of an atomic absorption line (about 2 pm) in order to avoid losses of sensitivity and linearity of the calibration graph.