Spectrophotometry

Measuring quantity and quality

Accurate measurement and reliable quality control of DNA, RNA and protein samples is a prerequisite for a multitude of assays in medical research and biochemical applications. By using a spectrophotometer to read the UV/VIS absorption spectrum of a compound in a given sample, it is possible to measure the signal and calculate its quantity. Spectral profiling, i.e. reading the absorption of a sample at a range of different wavelengths, can reveal further information about the quality and the composition of the sample, e.g. detecting impurities. The profiles of different sample types are unique; e.g. a pure RNA sample will give rise to a profile that is decidedly different from an RNA sample spiked with gDNA.

Reproducibility and linearity

In order to ensure that the measurements are reliable, serial dilutions of the samples should be made to calculate the linearity. The regression coefficient should optimally be >0.999, but this is difficult to achieve with manual measurements. Therefore it’s useful to employ automated spectrophotometry systems, providing the high system linearity and reproducibility required for many molecular biology applications.

For information about products based on this technology, see QIAxpert.