Nucleic acid concentrationandpuritycan be determined by measuring their absorbance using a spectrophotometer. One of the most common methods for nucleic acid isolation analysis is to use a spectrophotometer. The NanoDrop is a specialized spectrophotometer that can measure absorbance from only 0.5-2 μl of sample. It draws the sample into a column by exploiting surface tension (creating something like a tiny fibre optic of DNA solution) and measures the light that passes through it at different wavelengths.
Other techniques need to be utilized to address theintegrity or level of degradation.
Figure 1:A example output of a spectrophotometric RNA quantification of a high-quality RNA sample.
Usually, a spectrophotometer or a nano-drop will automatically estimate the concentration of your sample from the input data - you would have to indicate either what is the nature of your sample (RNA, DNA or Proteins) and/or which wavelength you would like to measure. For additional confidence in your results, it is recommended to run several duplicates of your samples (if you have enough material) and compare the resulting concentration measurements.