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Determination of Selenium by Atomic absorption spectroscopy (AAS) (CAT#: STEM-ST-0168-WXH)

Introduction

Selenium is a mineral found in the soil. Selenium naturally appears in water and some foods. While people only need a very small amount, selenium plays a key role in their metabolism.




Principle

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.
Atomic absorption spectroscopy (AAS) is based upon the principle that free atoms in the ground state can absorb light of a certain wavelength. Absorption for each element is specific, no other elements absorb this wavelength.

Applications

Atomic absorption spectrometry (AAS) is an easy, high-throughput, and inexpensive technology used primarily to analyze elements in solution. As such, AAS is used in food and beverage, water, clinical research, and pharmaceutical analysis.

Procedure

1. Creating a steady state of freely dissociated ground state atoms using a heat source (flame)
2. Passing light of a specific wavelength through the flame. The wavelength corresponds to the amount of energy required to excite an electron from (typically) the ground to first excited state for a specific element.
3. Measuring the amount of the light absorbed by the atoms as they move to the excited state (the atomic absorption).
4. Using the measured absorbance to calculate the concentration of the element in a solution, based on a calibration graph.

Materials

• Spectrometer
• Radiation sources
• Atomizers
• Atomic absorption
• Spectrophotometer