Instrumentation of Atomic Absorption Spectrophotometry and its Applications

About the Study

For many atoms, the electron density between their excited state and ground state orbital is too large to allow for the thermal excitation of a sufficient number of electrons. Atomic Absorption Spectrophotometry (AAS) may be utilized when energy differences are too significant to obtain an emission reading. In a flame, metal atoms vaporize while radiation passes through the flame. The vaporized atoms will absorb radiation with energy equal to the difference between their ground state and the excited state in this situation since they are mostly in their ground state and are not emitting energy.

The number of atoms in the ground state that are capable of being excited is far larger than the relatively small percentage that does so and release energy in Atomic Emission Spectroscopy (AES). As a result, AES is not as sensitive as AAS. The only light source where considerable absorption can be seen after it passes through the sample is where the light is created by excitation of the atoms of the element being studied since the breadth of absorption or emission lines in atomic spectra is exceedingly tiny.

The metal to be examined is coated on the cathode of the lamp, which is known as a "hollow cathode lamp." The excitation of the zinc (zn) atoms, for instance, produces a small range of radiation at 214 nm, which can be effectively absorbed by the atoms in the flame when a Zn-coated cathode is employed in the analysis. The drawback of this is that only one element may be analyzed at once, and the lamp must be changed each time a new element is being examined. The speed of multi-element analyses is improved by modern instruments' use of roughly 12 lamps positioned on a carousel that may be mechanically rotated in line with the flame.

Instrumentation

A source of light: A hollow cathode lamp that has been covered in the element being studied.

Flame: Typically, an air/acetylene flame produces a flame with a temperature of about 250°C.

Temperatures of up to 300°C can be created using nitrous oxide or acetylene, which are necessary to volatilize salts of elements like calcium or aluminum.

Monochromator: The wavelength being released by the hollow cathode lamp is set to be monitored by the monochromatic, which is utilized to reduce the width of the band of radiation being checked. This eliminates interference from radiation coming from the flame, the hollow cathode lamp's filler gas, and other components of the sample.

Detectors: Photosensitive cells are used as the detector.

Applications

• AAS is employed in several limit tests for metallic impurities, including lead in bismuth subgallate, strontium and magnesium in calcium acetate, and palladium in carbenicillin sodium.

• Prior to being incorporated into formulations, AAS is mostly utilised in limit tests for metals in medications.

• To conduct limit testing for lead and nickel in sugars and polyols, BP assays use AAS.

Conclusion

Atomic absorption spectrometry is also another term for AAS. The study of the interactions between energy and matter is known as spectroscopy, but the use of this knowledge as a measuring method is known as spectrometry. Atomic absorption spectroscopy is a vital part of many processes and has a variety of laboratory and testing applications in industrial, clinical, and research contexts. Around three-quarters of the chemical elements that make up the earth are metals, which are present in the natural world all around. Metals can be pollutants as well as desirable components in some materials. As a result, checking for metallic content is an essential step in a variety of procedures.