Difference Between ICP OES and ICP AES

Difference – ICP OES vs ICP AES

Both ICP OES and ICP AES describe the same technique of analyzing different sample solutions with the use of a plasma and a spectrophotometer. The term ICP OES refers to Inductively Coupled Plasma Optical Emission Spectrometry. This name is given since this technique is optical (done in relation to the physical action of light). The term ICP AES refers to Inductively Coupled Plasma Atomic Emission Spectrometry. This name is given because the technique is done by exciting atoms present in the sample that is going to be analyzed. There is no difference between ICP OES and ICP AES since they are two names for the same technique.

Key Areas Covered

1. What is ICP OES
     – Definition, Technique
2. What is ICP AES
      – Definition, Technique
3. What is the Difference Between ICP OES and ICP AES
      – Comparison of Key Differences

Key Terms: Argon, Emission Rays, Inductively Coupled Plasma Atomic Emission Spectrometry, Inductively Coupled Plasma Optical Emission Spectrometry, Photons, Plasma, Spectrophotometer

What is ICP OES

ICP OES is inductively coupled plasma optical emission spectrometry. It is a laboratory technique which is used to determine the composition of elements in a sample with the use of a plasma and a spectrophotometer. Therefore, the ICP OES is composed of two components: ICP and optical spectrophotometer. 

Figure 1: ICP OES System

ICP OES system analyzes samples in its liquid phase. The sample is often dissolved in water. This solution is then driven through a nebulizer using a peristaltic pump. Nebulizer conducts the solution into a spray chamber. In the spray chamber, an aerosol is formed from the sample solution. Then this aerosol enters an Argon plasma (plasma is one of the states of matter).

When plasma energy is given to the sample, the atoms of different elements in that sample are excited. This happens due to absorption of energy by the atoms. The excited state is unstable due to the high energy level. Therefore, the excited atoms tend to come back to a lower energy level (ground level). Then, the energy is released. The energy is released in the form of photons in emission rays/spectrum rays. By detecting these rays, we can determine the photon wavelength of each emission ray. The type of elements and their composition can be determined by observing the wavelengths and their intensities. This is because each element has an own characteristic emission spectrum.

Formation of the plasma phase includes supplying argon gas to the coil of a torch (made of quartz), followed by applying a high voltage to that coil. This creates an electromagnetic field inside the torch tube, which results in ionization of Argon. Eventually, the plasma phase of Argon can be obtained. This plasma has a high density of electrons and a high temperature. This energy can be used to excite atoms in the sample.

Basic features of ICP OES include the ability to analyze several elements simultaneously, minimum chemical interferences, high sensitivity, wide linear final curve, etc. Applications of ICP OES includes trace analysis of soil samples and water samples, forensic analysis, Boron in glasses, etc.

What is ICP AES

ICP AES is Inductively coupled plasma atomic emission spectroscopy. Both the terms ICP OES and ICP AES are used to describe the same technique. The name ICP AES is used because this technique is done regarding the excitations of atoms.

Difference Between ICP OES and ICP AES

ICP OES is inductively coupled plasma optical emission spectrometry while ICP AES is Inductively coupled plasma atomic emission spectroscopy.

Summary – ICP OES vs ICP AES

Both ICP OES and ICP AES describes the same technique of spectroscopy. There is no difference between ICP OES and ICP AES. Here, a sample can be analyzed by exciting the atoms of the elements present in that sample by providing plasma energy. When the excited atoms release energy to come back to the ground state (which has a lower energy), the released energy can be detected as emission spectra of different wavelengths. By comparing the wavelengths with standard data and by determining the intensities of the spectra, we can determine the elements present in that sample and even their composition.

References:

1. “ICP-OES.” General Instrumentation, Available here.
2. “Principle of ICP Optical Emission Spectrometry (ICP-OES).” Principle of ICP Optical Emission Spectrometry (ICP-OES) : Hitachi High-Technologies GLOBAL, www.hitachi- Available here.
3. “ICP-AES Technique Description.” USGS, Available here.

Image Courtesy:

1. “ICP OES 720” By Docentem – Own work (CC BY-SA 3.0) via Commons Wikimedia