The Qubit 2.0 Fluorometer

The Next Generation in Nucleic Acid and Protein Quantitation

Accurate and sensitive nucleic acid and protein quantitation demands the highest levels of performance, from the analyte-specific assay to the analytical instrument. The Qubit 2.0 Fluorometer is Life Technologies’ second-generation desktop fluorometer designed to work seamlessly with our highly selective Qubit DNA, RNA, and protein assays. Together, they form the Qubit Fluorometric Quantitation Platform, which delivers unprecedented accuracy and sensitivity through sophisticated and proven fluorescence-based technologies.

New Features of the Qubit 2.0 Fluorometer

The Qubit 2.0 Fluorometer (Figure 1) provides the same accuracy you’ve come to expect from the original Qubit (1.0) Fluorometer, but with even more speed and less effort than before. The Qubit 2.0 Fluorometer has an upgraded, robust design, complete with a color touch screen and intuitive user interface (Figure 2). Navigation buttons for running samples, calibrating standards, and reviewing results are continually accessible at the bottom of the screen, eliminating multiple steps and confusion. And no more scrolling through selections one by one using “Up” or “Down” arrows—the Qubit 2.0 Fluorometer is equipped with list wheels and scroll bars for clear and simple line selection. Importantly, all functionality has been validated for convenient use with gloves (e.g., latex, nitrile) commonly worn in a lab setting.

Additionally, the Qubit 2.0 Fluorometer includes a new graphing feature that shows the standard curve after calibration and displays up to 10 data points. Sample data are automatically stored in a .csv file format and can be accessed at any time by navigating to the data screen. This stored data file contains all relevant sample information, including time/date stamp, concentration readout, units, and assay type, as well as raw fluorescence data for assay troubleshooting. A built-in dilution calculator allows users to quickly determine sample content, and concentrations determined using this calculator are also stored in the data file. Furthermore, although each Qubit assay function comes preprogrammed with default unit readouts, the Qubit 2.0 Fluorometer enables users to change unit output based on their own preference.

For simpler identification and sorting, the data files can be renamed directly using the instrument‘s full alphanumeric keypad. Data can then be transferred to a computer via a USB drive for more thorough analysis—no direct connection to a computer is required at any time, neither for instrument operation nor data transfer. Likewise, any upgrades can easily be made using a USB drive and firmware downloaded from www.invitrogen.com/qubit. For convenience, every Qubit 2.0 Fluorometer comes with a 2 GB USB drive equipped with .pdf files of the complete instrument user manual and all Qubit assay protocols.

Figure 2. Easy workflow of the Qubit 2.0 Fluorometer.

Exceptional Selectivity of the Qubit Assay Kits

The Qubit 2.0 Fluorometer in combination with the Qubit assays yields analyte-specific quantitation with unprecedented accuracy, sensitivity, and simplicity for both routine analyses and for rare or hard-to-obtain samples. The basis of each Qubit assay is a Molecular Probes dye that emits fluorescent signals only when bound to specific target molecules, even when targets are present at low concentrations.

The most significant advantage of the Qubit DNA and RNA assays is their selectivity. UV absorbance–based analysis cannot be used to quantitate DNA or RNA in samples containing a mixture of both. In contrast, the Qubit DNA and RNA assays are able to accurately measure DNA and RNA, respectively, in the same sample (Figure 3). We found that the DNA concentration of a sample containing equal parts DNA and RNA can be measured within 2% of the actual concentration using the Qubit dsDNA BR (Broad Range) Assay Kit. Furthermore, in a sample containing a 10-fold excess of RNA over DNA, the DNA concentration was measured to be only 7% higher than the actual concentration.

Similarly, the Qubit protein assay compares favorably with other absorbance- and fluorescence-based assays by providing low protein-to-protein variability, rapid quantitation, and accurate results. The Qubit protein assay is insensitive to many common contaminants, including reducing agents, nucleic acids, and free amino acids, and has an optimal detection range of 0.25–5 μg (sample starting concentrations of 12.5 μg/mL–5 mg/mL).

Each Qubit Assay Kit provides concentrated assay reagent, dilution buffer, and prediluted standards, and all assay reagents are stored at room temperature. The protocol is easy: Simply dilute the reagent using the buffer provided, add your sample (any volume between 1 and 20 μL), and read the concentration using the Qubit 2.0 Fluorometer after a 2-minute incubation (allow 15 minutes for the protein assay). With the Qubit 2.0 Fluorometer, all assay settings and calculations are performed automatically, and the Qubit assay signal is stable for 3 hours. Qubit Assay Kits (formerly called Quant-iT assays) are compatible with both the Qubit 2.0 Fluorometer and the original Qubit (1.0) Fluorometer.

Figure 3. Selectivity of the Qubit DNA and RNA assays compared with UV spectroscopy. Triplicate samples containing lambda DNA (10 ng/μL) and varying amounts of E. coli ribosomal RNA (0–100 ng/μL) were assayed using Qubit DNA BR and Qubit RNA BR assays and the Qubit 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 PerkinElmer® Lambda 35 Spectrophotometer. The red and orange trendlines indicate the actual concentrations of DNA and RNA, respectively, in the starting samples. The data indicate that UV analysis cannot distinguish between DNA and RNA.

Qubit Fluorometric Quantitation Platform: An Integrated Solution

The Qubit Fluorometric Quantitation Platform is an essential component of any workflow where high accuracy is required for downstream applications.