DNA quantification has been traditionally performed by measuring absorbance of the sample at 260nm. Cuvette-based instruments have been used for many decades, but to a limited extent due to the large consumption of sample material. A real breakthough in the use of the method happened when the technique could be applied to the measurement of tiny drops in microvolumes using instruments such as the Colibri Microvolume Spectrometer.
Disadvantages of this method for DNA quantification include its limited sensitivity and the impossibility to distinguish between single-stranded and double-stranded DNA. To overcome these limitations, there are a variety of different DNA and RNA quantification kits available that rely on fluorescence instead of absorbance. For example, PicoGreen® is a fluorescent dye that undergoes a dramatic fluorescence enhancement upon binding to dsDNA that can be measured using a microplate fluorometer.
PicoGreen® is a registered trademark of Thermo Fisher Scientific.