Applications of AAS and AES:

Previously you have studied about basic principles and instrumental aspects of atomic absorption spectrophotometry (AAS) and atomic emission spectrometry (AES) respectively. You will recall which atomic absorption spectrophotometry concerns the absorption of radiation by the atomised analyte element in the ground state; the atomisation being achieved by the thermal energy of the flame or electrothermally in an electrical furnace. The wavelength(s) of the radiation absorbed and the extent of the absorption form the basis of the qualitative and quantitative determinations respectively.  On the other hand atomic emission spectrometry concerns the emission of radiation by the suitably excited atomic vapours of the analyte; the atomisation as well as the excitation being achieved by any of the numerous available energy sources such as flame arcs, sparks, or plasmas. Here, the emitted radiation and its intensity form the basis for the qualitative and quantitative applications of the technique. You have also known about flame emission spectrophotometry (FES), another atomic emission technique, commonly called as flame photometry. You would recall that it is an easy, fast and inexpensive method for routine analysis of alkali and alkaline earth metals such as, potassium, sodium, lithium, calcium and barium in environmental, biological and clinical samples especially in biological fluids and tissues.

In this unit, we take up some of the important applications of atomic absorption spectrophotometry and atomic emission spectrometry. We will begin the unit with recalling the salient features of the two techniques and then take up the applications of AAS and AES. In the next block you would learn about some miscellaneous spectroscopic methods.

Objectives

After studying this unit, you will be able to:

• Outline the salient characteristics of atomic absorption spectrophotometry and atomic emission spectrometry,
• Contrast and compare atomic absorption spectrophotometry and atomic emission spectrometry,
• Enlist various areas of applicability of atomic absorption spectrophotometry and atomic emission spectrometry,
• Define the merits and limitations of atomic absorption spectrophotometry and atomic emission spectrometry,
• Define some representative applications of atomic absorption spectrophotometry and atomic emission spectrometry,
• Rationalise a complementary nature of atomic absorption spectrophotometry and atomic emission spectrometry.