Qubit is specific for DNA or RNA.
Selectivity of the Qubit® assays compared to UV spectroscopy. Triplicate samples containing lambda DNA (10 ng/µL) and varying amounts of ribosomal E. coli RNA (0–100 ng/µl) were assayed using Qubit® DNA BR and Qubit® RNA BR assays on the Qubit® 2.0 Fluorometer according to kit protocols. The same samples were subsequently measured in triplicate using a NanoDrop® ND-1000 Spectrophotometer, and single measurements were made using a Perkin Elmer Lambda 35 Spectrophotometer. The concentrations indicated are the concentrations of DNA and RNA in the starting samples, before dilution in the Qubit® assay tubes. The red and orange trendlines indicate the actual concentrations of DNA and RNA, respectively, in the starting samples. The actual concentration of nucleic acid was set by diluting pure, concentrated solutions of DNA and RNA to an optical density of 1.0 at 260 nm using a Perkin Elmer Lambda 35 Spectrophotometer. The concentrations of the stock solutions were then calculated and used for all subsequent dilutions. With UV analysis, results for samples containing both DNA and RNA are nondiscriminatory—you cannot distinguish one from the other.
