Polymerase Chain Reaction, sometimes called Molecular Photocopying,” and is a fast and inexpensive way to amplify small segments of a persons DNA. Amplification is important to help in detecting very small amounts of viral material.

Kary B. Mullis was awarded the Nobel Prize for Chemistry in 1993 for the important discovery of this technique.

Going a step (or two steps) further, quantitative PCR or qPCR adds two important elements to the standard PCR process.

• Florescent dye

• Fluorometer (a device used to measure parameters of visible spectrum fluorescence)

In combination with appropriate standard curves and reference values, this real-time information about reaction rates and times translates into information about relative and absolute amounts of DNA present.

These two elements turn qPCR from a processing step in another procedure – to a measurement technique in its own right. 

Thermal cyclers meant for use with qPCR include a fluorometer to detect that fluorescence.

The fluorometer detects that fluorescence in real time as the thermal cycler runs, giving readings throughout the amplification process of the PCR.

As a result, quantitative PCR is also called real-time PCR or RT-PCR.

This technology and process makes it possible to “multiplex” qPCR and measure multiple DNA targets, as long as each target’s corresponding probe fluoresces at a different frequency.