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The Qubit fluorometer is a small instrument used for quantification of DNA, RNA, and protein and used in many different applications. The new generation of this instrument, Qubit 2.0 Fluorometer was released Nov. 15, 2010. Another quantification method is the UV (Ultraviolet)-absorbance method.

The difference between the two methods is that the Qubit fluorometer uses fluorescent dyes to determine the concentration of nucleic acids and proteins in a sample. The UV-absorbance method uses a spectrophotometer to measure the natural absorbance of light at 260 nm (for DNA and RNA) or 280 nm (for proteins). The more DNA, RNA or protein in the sample, the more light is absorbed. The absorbance is a natural property of DNA, RNA, free nucleotides, proteins and some amino acids and many other compounds as well. Because so many molecules absorb light at 260 nm, this measurement is subject to inaccuracy due to potential contamination of the sample with these other molecules. In addition, using the absorbance method, it is not possible to distinguish between DNA, RNA, protein or free nucleotides or amino acids in the sample, leading to potentially highly inaccurate measurements.