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Analysis of organic and inorganic selenium anions by ICP-AES (CAT#: STEM-ST-0179-WXH)

Introduction

Selenium is widely but variably distributed on earth, having an average abundance in the lithosphere of about 0.05 ppm. Both organic and inorganic selenium compounds are present in the oceans. Oceanic selenium concentration increases with depth, and concentrations as high as 0.2 p~g/1 are found in deep ocean waters. The aquatic chemistry of selenium is complicated since it can exist in four different oxidation states and in a variety of inorganic and organic compounds. Microorganisms play an important role in controlling the chemical speciation of selenium in the aquatic environment.




Principle

Atomic emission spectroscopy (AES) is a method of chemical analysis that uses the intensity of light emitted from a flame, plasma, arc, or spark at a particular wavelength to determine the quantity of an element in a sample. The wavelength of the atomic spectral line in the emission spectrum gives the identity of the element while the intensity of the emitted light is proportional to the number of atoms of the element. The sample may be excited by various methods.
Inductively coupled plasma atomic emission spectroscopy (ICP-AES) uses an inductively coupled plasma to produce excited atoms and ions that emit electromagnetic radiation at wavelengths characteristic of a particular element.

Applications

Common applications of atomic emission spectroscopy are in the analysis of trace elements in soils, water, metals, biological specimens, clinical specimens, food, physical evidence such as glass, and other solids.

Procedure

1. Prepare sample for analysis
2. Convert solution into aerosol
3. Introduce aerosol into excitation source
4. Atomization and excitation
5. Detection of emission lines

Materials

• ICP (Inductively Coupled Plasma) source
• Atomizer
• Monochromators
• Detectors
• Amplifiers