Electrothermal Vaporization ICP Optical Emission Spectroscopy (ETV-ICP-OES)

Electrothermal Vaporization ICP Optical Emission Spectroscopy (ETV-ICP-OES)

The method uses Electrothermal Vaporization (ETV) to vaporize a sample into a carrier gas by controlled heating, followed by atom excitation in high temperature plasma and subsequent atomic emission spectra analysis using Optical Emission Spectroscopy (OES). ETV is achieved in a small graphite tube furnace, into which the sample is placed in a graphite boat. Argon is usually the carrier gas, along with a modifier gas. The carrier and modifier gases flow through the heated tube and transport the vaporized sample as dry aerosol, into the next stage of high temperature plasma. The sample can also be introduced after making a slurry, using a nebulizer. The plasma generator is an inductively coupled (ICP) type, comprising a quartz tube surrounded by an induction coil. At high plasma temperatures, atoms are excited to higher energy levels and upon their return to ground state, their optical emissions (photons) exhibit characteristic wavelengths, depending on the element. The intensity of emissions depends on the concentration of the excited atoms. These characteristic emissions are separated and measured by spectroscopy (OES). When calibrated against standards, quantitative estimates of elemental compositions can be obtained.

The ETV-ICP-OES technique is very useful in the analysis of trace elements in a variety of applications such as coal analysis, metals and alloys, biomaterials and environmental analysis. Samples can be in the form of solids as well as slurries. Detectable concentrations are in the order of picograms.

Video 01: Inductively Coupled Plasma- Optical Emission Spectrometry (ICP-OES)

Common Uses of ETV-ICP-OES

• Analysis of major, minor and trace elements in coal
• Elemental analysis of oilfield waters
• Elemental analysis on pure metals as well as alloys
• Elemental analysis of biomaterials
• Trace element analysis in ceramic materials
• Environmental samples analysis for trace elements
• Forensic analysis of human hair for trace elements

Advantages of ETV-ICP-OES

• Extremely sensitive technique, detectable concentrations are in the order of picograms.
• Atom and ion spectra can be used
• Rapid and economical
• Introduction of samples without sample degradation or dilution while remaining contamination-free. It is possible to sample both liquids and solids.
• Graphite can be sampled and calibrated using current standards and reference materials, which is not possible with the GDMS (Glow Discharge Mass Spectrometry) approach.
• This technique is very effective due to the great transmission efficiency of the gasses used.
• No matrix spectral interference is present.
• Simple and quick acquisition: Automated loading allows up to 50 samples to be analyzed daily. 
• Suitable for standard investigation.
• Most elements in the periodic table have very low detection limits (1–50 g/kg = ppb) (parts per billion).
• Ideally suited to insulation made of carbon, carbon/carbon composites, and pure graphite.
• This technique provides very low limits of detection for most elements.

 Limitations of ETV-ICP-OES

• Overlap of sensitive spectral lines due to rich spectra
• High background radiation

Industrial Applications of ETV-ICP-OES

• Fossil fuels
• Ceramics
• Metallurgical
• Environmental
• Biomaterials