Atomic absorption spectroscopy

Atomic absorption spectroscopy

1. Atomic Absorption S pectroscopy

2. Syed Sheraz Ali Shah (01-161142-106) Zeeshan Ahmad (01-161142-067) Talha Abbasi (01-161142-058) Muhammad Abdullah (01-161141-026) Zain Naeem (01-161132-060) Nabeel Salamat (01-161142-095) Waseem Rasool (01-161141-063) Group members

3. The technique was introduced in 1955 by Alan Walsh in Australia ( 1916 – 1998 ). The first commercial atomic absorption spectrometer was introduced in 1959 . History

4. Atomic absorption spectroscopy (AAS) is a spectroanalytical procedure for the quantitative determination of chemical elements using the absorption of optical radiation (light) by free atoms in the gaseous state . A technique for determining the concentration of particular metal elements in a sample. Introduction

5. Atomic Absorption Spectroscopy is a very common technique for detecting metals and metalloids in samples. I t is very reliable and simple to use. It also measures the concentration of metals in the sample. It can analyze over 62 elements. Why Atomic Absorption Spectroscopy is important?

6. Elements detectable by atomic absorption are highlighted in pink color in periodic table.

7. Light source Nebulizer Atomizer Monochromators Detector Read out device Components

8. The analyzed sample must contain the reduced metal in the atomic vaporized state. Commonly, this is done by using the heat of a flame to break the chemical bonds and form free, unexcited atoms. Atomic absorption spectroscopy is based on the principle that when a beam of electromagnetic radiation is passed through a substance, the radiation may either be absorbed or transmitted depending upon the wavelength of the radiation.  Principle

9. The absorption of radiation would bring about an increase in the energy of the molecule. The energy gained by the molecule is directly proportional to the wavelength of radiation. The increase in the energy of the molecule leads to the electronic excitations where electrons jump to higher energy levels.

10. Hollow cathode lamp are the most common radiation source in AAS. It contain a tungsten anode and hollow cylindrical cathode made of the element to be determined. These are sealed in a glass tube with an inert gas (neon or argon ).   Light source

11. Cross section of hollow cathode tube

12. Suck up liquid samples at controlled rate. Mix the aerosol and fuel and oxidant thoroughly for introduction into flames . Nebulizer

13. Element to be analyzes to be in atomic state. Atomization is separation of particles into individual molecules and breaking molecules into atoms. Two types of Atomizer. Flame atomizer. Graphite tube atomizer. Atomizer

14. To create flame, we need to mix an oxidant gas and a fuel gas. Liquid or dissolve samples are typically used with flame atomizer. Flame Atomizer

15. Uses a graphite coated furnace to vaporize the sample. The graphite tubes are heated using a high current power supply. Graphite Tube Atomizer

16. This is very important part in an atomic absorption spectrometer. A monochromator is used to select wavelength of light which is absorbed by sample and to execute other wavelengths .   Monochromator

17. The light selected by the monochromator is directed onto a detector, typically a photomultiplier tube, whose function is to convert the light signal into an electrical signal proportional to the light intensity. Detector

18. AAS schematic diagram

19. https://www.youtube.com/watch?v=_KZjb9G3hB8 Video

20. A calibration curve is used to determine the unknown concentration of an element. The instrument is calibrated using several solutions of known concentrations and a calibration curve is produced. The calibration curve shows the concentration against the amount of radiation absorbed. Result and Calibration Curves

21. The absorbance of standard solutions with a range of concentrations is measured and plotted on a graph to obtain a calibration curve.

22. The detection limits achievable for individual elements are important in determining the usefulness of an analytical technique for a given analytical problem. Detection limit ranges

23. Determination of even small amount of metals (lead, mercury, calcium and magnesium). Environmental studies: drinking water, ocean water, soil . Food industry, food analysis. Used in Industrial raw material. Used in pharmaceutical industry. Geological analysis Uses of AAS

24. Biological analysis Analysis of soil. Petroleum Industry Mining

25. Accuracy Sensitivity Cost Accessibility Pros of AAS

26. Lack of versatility Equipment Precision Cons of AAS

27. Atomic absorption spectroscopy is a spectroanalytical procedure for the quantitative determination of chemical elements using the absorption of optical radiation (light) by free atoms in the gaseous state. It can also be used to identify the trace element in soil samples, water etc. The concentration of unknown element is find by plotting and using the calibration curve. Conclusion

28. http://www1.lasalle.edu/~prushan/Intrumental%20Analysis_files/AA-Perkin%20Elmer%20guide%20to%20all!. pdf https://lincolnparkhs.org/ourpages/auto/2010/9/26/37121222/Chapter%2006%20-%20Atomic%20Absorption%20Spectroscopy.pdf http:// www.liskeard.cornwall.sch.uk/images/Liskeard-Sixth-Form/Atomic-Absorption-Spectrometry.pdf   https:// www.slideshare.net/sharmasuriti/atomic-absorption-spectroscopy-15185397   References