A radionuclide is an atom with an unstable nucleus that can spontaneously transform into another nucleus or energy level. When this occurs, the energetic particles or waves given off by these radionuclides are collectively known as radiation. There are generally three types of radiation, which have been given the names alpha, beta and gamma. An alpha particle is a helium nucleus, a beta particle is an electron and a gamma ray is a photon. As all three types of radiation can be ejected from a nucleus with great energy, the damage they can cause to biological cells continues to be a serious safety concern due to the risk of human or animal contact with natural or manmade radioactive materials. There are several techniques that can detect radiation, but one of the most common devices used by scientists is a liquid scintillation counter.

A liquid scintillation counter measures the activity of radionuclides in a sample by analyzing photons emitted. The measurement process begins by dissolving a sample in a unique scintillation solution, also known as a cocktail, which consists of a compatible solvent and a fluor solute that emits photons upon excitation by light. The kinetic energy of the particles spontaneously emitted from the sample’s radionuclides is absorbed by solvent molecules, making them excited. The energy of the excited solvent molecules is then emitted as UV light, allowing the solvent molecules to return to ground state.

When an excited solvent molecule transfers its energy to a solute molecule, the solute molecule in turn becomes excited. As these excited solute molecules return to ground state, photons are emitted in the form of blue light flashes. This reaction takes place inside the dark enclosure of a liquid scintillation counter, where these blue light flashes are captured by a photomultiplier tube and converted into electrical impulses. These impulses are then analyzed to both identify and quantify the radioactive elements that are present in the sample.

Outside of basic research, liquid scintillation counting is often used for testing radiation content in drug discovery applications. The technique works best with isotopes that are low-energy beta emitters, including tritium and carbon-14, which are commonly used to tag pharmaceutical compounds and other life science molecules. The technique is also frequently used within energy production facilities or to test environmental samples for radioactive contamination.

PerkinElmer is the clear market leader, having introduced in 2015 its Tri-Carb and Quantulus GCT families of liquid scintillation counters. The company is also the leading supplier of radiochemicals. Other significant suppliers include Hidex and MP Biomedicals.

The total market for liquid scintillation in 2016 was about $100 million, which includes sales from cocktails as well as the instruments themselves. Due to the mature nature of the technique, as well as a general trend toward avoiding technologies and infrastructure that use nuclear energy, the market for radiation detection is expected to remain flat, if not decline moderately.

Liquid Scintillation at a Glance

Leading Vendors:

• PerkinElmer
• Hidex
• MP Biomedicals

Largest Markets:

• Pharmaceuticals
• Government
• Biotechnology

Instrument Cost:

• $15,000–$80,000