ATOMIC ABSORPTION SPECTROSCOPY

BY- SREELAKSHMI (MSIWM012)

Atomic absorption spectroscopy has proven to be the most powerful method in the use of liquid-density implants since it was introduced by Alan Walsh in the mid-1950s.

More than 60 -70 items including the rarest earth metals determined by this method in the focus from tracking to large numbers. The direct use of this process is limited to instruments other than B, Si, As, Se & Te.

Several non-ferrous metals are weighed with indirect metals. Since atomic spectroscopy does not require sample correction it is an appropriate non-chemical tool as well.

Some elements, especially metals, play a vital role in biological processes, whether they are simple cofactors in enzymes, the atom in the macromolecule of living organisms such as iron in hemoglobin or magnesium in chlorophyll, or as toxins that affect the body.

The use of atomic spectroscopy will make important data available in understanding the biological roles of these substances.

In general, molecules enlarge the band spectra and atoms provide a clearly defined line of line. So, in atomic spectroscopy, the line spectra are studied. These lines are seen visually as light, corresponding to a certain length of the boundaries, which are the atomic emission rays or black lines against the luminous background, which is the atomic absorbing spectra.

On the surface of the element, the wavelength at which the absorption or discharge is detected is associated with changes in which a small change in energy occurs. In general, the appearance of a number of cells, the concentration of atoms is not measured directly in solution but is converted into free atoms.

The process of converting an analyte into a solid, liquid form, or solution into a free gas atom is called atomization. Atoms that are volatilized can be flame or electro thermally in the oven.

In this case, the elements will easily penetrate or emit monochromatic radiation at the right distance. Usually nebulizers (atomizers) are used to spray a standard solution or test in the flame where light is transmitted. Alternatively, the light beam is transferred, to the oven, through a hole containing the inspired apparatus.

Principle

The volatilization of molecules in the sun produces free atoms. These free atoms are happy when light of a certain length is able to emit spectral lines corresponding to the energy required for the electronic transition from the earth’s state to a happy state, allowed to pass through flame. The atomic spectra obtained is fully determined by the object involved and the amount of light concentrated is equal to the number of atoms in the path of light. Therefore, in addition to granting ownership of the material in the sample, this process of viewing and providing information on the quantity of the material.

INSTRUMENTATION

For all types of atom-absorbing spectrometer, the following components are required:

Radiation source:

The source should be such that it emits strong rays of the element to be determined, usually the resonance line of the object. It is almost impossible to separate the maximum length of resonance from a continuous source using a prism or diffraction grating or both at the same time. This problem was solved by the invention of empty cathode emission lamps. Such lamps emit monochromatic radiation element analyzes.

(a) Empty Cathode Lamp:

The cathode contains an empty cup in which the element will be cut. The anode is a tungsten wire. Both electrodes are inserted into a tube containing internal gas (argon or neon). The light window is constructed using quartz, silica or glass. The exact metal depends on the length of the scale to be transmitted. When a potential of approximately 3000V is used between these two electrodes, electrons trigger the immersion of gas into the lamp. These ions which receive enough energy to decompose atoms in the cathode, that is, explode other atoms of iron. These atoms regenerate and when they return to the ground, they begin to release the visible metal used to build the cathode (The light emitted spectrum corresponds to the elevation of the cathode emissions and the gas in the lamp. filling, and selection of very sharp spectral lines to obtain better sensitivity, without cases of disruption caused by other elements). The pressure stored in the lamp is 1 to 5 torr. Each blank cathode lamp emits a wide range of metal used in the cathode; this looks bad as a separate lamp should be used for each item to be analyzed. Another hollow cathode lamp is a wireless emission lamp (EDL) now made available for its light intensity of almost 10-100 times but not as stable as HCL (hollow cathode lamps). They are made of a closed quartz tube containing the salt of the substance and gas entering. The radio frequency field is used to cool the gas which makes the metal ionized. These lamps are usually reserved for items such as As, Hg, Sb, Bi and P.

Working of Atomic Absorption Spectrometer

Practically the meter is adjusted to learn zero absorption when spraying a blank solution in flame and the uninterrupted light of an empty cathode lamp passes through a photomultiplier tube. When a solution with a suction type is inserted then a portion of the light is applied which leads to a decrease in the intensity of the light which falls into the photomultiplier and produces a deviation from the meter needle. Standard object solutions are used to create a measuring curve where the content of the test solutions can be measured.

Applications

  • Used to determine the trace of a metal in a liquid.
  • Used in clinical laboratories for the removal of body fluids.
  • Estimation of soil and water samples.
  • Determination of lead in petrol.
  • Determination of metallic elements in food industry

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