Qubit fluorometer
The Qubit fluorometer is a laboratory instrument developed and distributed by Invitrogen, which is now a part of Thermo Fisher. It is used for the quantification of DNA, RNA, and protein.
The first model of the Qubit was a winner of the 2007 R&D 100 award from R&D Magazine. The Qubit Flex, a later model of the Qubit, was a finalist for the same award in 2020.
Method
The Qubit fluorometer uses fluorescent dyes to determine the concentration of either nucleic acids or proteins in a sample. Specialized fluorescent dyes bind specifically to the substances of interest.The Qubit assays were previously developed and manufactured by Molecular Probes. Each dye is specialized for one type of molecule. These dyes exhibit extremely low fluorescence until bound to their target molecule. Upon binding to DNA, the dye molecules assume a more rigid shape and increase in fluorescence by several orders of magnitude, most likely due to intercalation between the bases.
The Qubit fluorometer correlates the level of fluorescence with known concentrations of probes. This process enables it to transform the fluorescence data into a quantified concentration measurement. Different kits are required for different concentration ranges.
| Reagent/Assay | Assay range | Sample starting concentration range |
| Qubit dsDNA HS Assay | 0.2–100 ng | 10 pg/μL–100 ng/μL |
| Qubit dsDNA BR Assay | 2–1,000 ng | 100 pg/μL–1 μg/μL |
| Qubit ssDNA Assay | 1-200 ng | 50 pg/μL-200 ng/μL |
| Qubit RNA Assay | 5–100 ng | 250 pg/μL–100 ng/μL |
| Qubit RNA BR Assay | 20–1,000 ng | 1 ng/μ-1 μg/μL |
| Qubit Protein Assay* | 0.25–5 μg | 12.5 μg/mL–5 mg/mL |