Atomic Absorption Spectroscopy.pptx

Nutrients are the substances which after ingestion, digestion, absorption and
assimilation, become a part of cell and thus maintains all cellular activities in the body.
Minerals are one of such nutrient. Some minerals are essential for cellular metabolism.

There are thirteen minerals considered as ‘essential’ viz., calcium, phosphorous, magnesium, sodium, potassium, iron, manganese, zinc , copper, selenium, chromium, cobalt and iodine.

1. MS. Ankita Avinash More GATE, SET Atomic absorption spectrometry (AAS) Ms. Ankita Avinash More

2. Nutrients are the substances which after ingestion, digestion, absorption and assimilation, become a part of cell and thus maintains all cellular activities in the body. Minerals are one of such nutrient. Some minerals are essential for cellular metabolism. There are thirteen minerals considered as ‘essential’ viz., calcium, phosphorous, magnesium, sodium, potassium, iron, manganese, zinc , copper, selenium, chromium, cobalt and iodine. These minerals are again classified depending upon their requirements in the body; macro minerals and micro or trace minerals. When body requires more than 100 mg of a mineral in 1 day then it is considered as macro minerals viz., calcium, magnesium, phosphorus, sodium and potassium. The minerals whose requirement is less than the said level will considered as trace minerals . Zinc, Iron, Manganese, Selenium, Copper, Cobalt are the trace minerals. Ms. Ankita Avinash More

3. Atomic absorption spectrometry (AAS) detects elements in either liquid or solid samples through the application of characteristic wavelengths of electromagnetic radiation from a light source. Individual elements will absorb wavelengths differently, and these absorbances are measured against standards. Depending on the light wavelength and its intensity, specific elements can be detected and their concentrations measured. Ms. Ankita Avinash More

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5. Principle The basic principles of AAS can be expressed as follows. Firstly, all atoms or ions can absorb light at specific, unique wavelengths. When a sample containing copper (Cu) for example, is exposed to light at the characteristic wavelength of Cu, then only the Cu atoms or ions will absorb this light. The amount of light absorbed at this wavelength is directly proportional to the concentration of the absorbing ions or atoms . When the atom is exposed to its own unique wavelength, it can absorb the energy (photons) and electrons move from a ground state to excited states. Furthermore , since the electronic structure of every element is unique, the radiation absorbed represents a unique property of each individual element and it can be measured. Ms. Ankita Avinash More

6. Atomic absorption spectroscopy (AAS) determines the concentrations of minerals in samples. It is a process involving the absorption by free atoms of an element of light at a wavelength specific to that element. This method is very sensitive and enables to detect small amount of an element of 1 ppm using flame procedure. Lower levels can be determined down to 0.001ppm using graphite furnace procedure. In their elemental form, metals will absorb ultraviolet light when they are excited by heat. For all non conducting elements (insulators) and for most of the electrons in atoms of conducting elements, the energy gap between ground state and first or higher energy level is very large. So, very energetic photons are required. Vacuum UV or X-ray is required to excite the atom. Ms. Ankita Avinash More

7. Instrumentation - An atomic absorption spectrometer uses these basic principles and applies them in practical quantitative analysis. A typical atomic absorption spectrometer consists of four main components: 1. light source 2. atomization system 3. monochromator 4. detection system Ms. Ankita Avinash More

8. Working - sample solution is aspirated into the spray chamber through capillary tube. The liquid sample is aerolized and mixed with combustible gases such as acetylene and nitrous in the spray chamber and burned in a flame . The individual atoms of the sample are released to form a cloud inside the flame. The atoms of the element get free. To bring it from ground state into an excited state by passing UV light is required through hollow cathode lamp. On absorbing UV light at specific wavelengths the ground state metal atoms get transitioned to higher electronic state. The region of the spectrum to be measured is selected by a monochromator . The isolated spectral line falls on the detector and the output is amplified and sent to a readout device meter, digital or analogue or through a computer data processing system. The data is processed through software. Ms. Ankita Avinash More

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12. Sample Preparation There are at least five methods of sample preparation 1. Wet ashing or acid digestion 2. Fusion 3. Pressure dissolution 4. Dry ashing 5. Microwave digestion [For details- Refer a Research paper] Ms. Ankita Avinash More

13. Advantages of Atomic Absorption Spectroscopy it is incredibly sensitive, measuring at parts per million ( ppm ). It can analyse specific elements because of the unique light-absorbent qualities of their atoms. AAS can determine concentrations of over 65 elements. It is a relatively simple process. It is inexpensive in comparison to other analytical techniques. Ms. Ankita Avinash More

14. Applications- Mining and Geology – The elemental composition of minerals and rocks provide valuable information on the commercial feasibility of conducting mining activities in areas explored. After mining, the ores and minerals need to be tested for composition for the efficiency of refining operations. Similarly, trace metal analysis is of great value in prospecting for oil and water deposits. With the help of AAS, the amount of gold can be quantified to determine Environmental Monitoring – Environmental monitoring for trace metal contamination of industrial effluents, oceans, rivers and lakes is important for establishing the safety of water for drinking and commercial use. It is important to establish if such samples are within the safety limits set by regulatory bodies. The analysis of drinking water is probably one of the most important applications of AAS, especially in places where the environment is not properly cared for Ms. Ankita Avinash More

15. Materials Development – Common properties of materials such as hardness, brittleness, grain size, crystallinity and amorphous nature are signifi cantly infl uenced by composition and trace metals. Trace metal analysis can provide useful information on the performance properties of such materials. Pharmaceuticals – Trace metal analysis plays an important role in formulation development, catalyst effi ciency and dosage limits. Most elements have a benefi cial role up to certain prescribed limits but beyond such limits the effects are harmful. Ms. Ankita Avinash More