Quant-iT™ RiboGreen™ RNA Reagent, 1 mL - FAQs

Why am I getting negative fluorescence values with my Qubit Assays?

Negative fluorescence is a physical impossibility. It is an artifact from software autocorrecting for background signal. This means your reader is picking up and subtracting out background light at the cost of your data. Make sure to do a buffer-only control and assess the type of signal. You may need to switch to a different plate.

What are the linear ranges of the Quant-iT RNA kits?

The linear ranges are:

- Quant-iT RiboGreen RNA Assay: 1 ng/mL to 1 µg/mL
- Quant-iT RNA BR Assay: 20-1,000 ng
- Quant-iT RNA HS Assay: 5-100 ng

What is the difference between the Quant-iT RNA assay and the Quant-iT RiboGreen RNA Assay?

There are several differences:

- The Quant-iT RNA Assay uses a far-red dye (excitation 644 nm/emission 673 nm); the Quant-iT RiboGreen RNA assay uses a green fluorescent dye (excitation 500 nm/emission 525 nm).
- The Quant-iT RNA assay is more specific for RNA.
- Quant-iT RNA Assays are less sensitive than the Quant-iT RiboGreen RNA Assay.

Can I make my own assay for the Qubit Fluorometer?

Yes, you can, for Qubit instruments developed after the original Qubit (1.0) Fluorometer. See MyQubit assay instructions here (http://www.thermofisher.com/us/en/home/life-science/laboratory-instruments/fluorometers/qubit/qubit-assays/myqubit.html.html).

I have a crude lysate. Will the Quant-iT and Qubit assays work?

Generally, the cleaner the sample the better. Some salts, proteins, and detergents are tolerated in the assays; see the specific assay protocol for which ones and at what concentrations.

How does the accuracy and sensitivity of the Qubit quantitation assays using the Qubit fluorometer compare to a microplate reader?

The accuracy and sensitivity of the Qubit quantitation assays are the same as that of a microplate reader. This was a requirement during product development. The detection limits for each Qubit kit can be found on the corresponding product manual, which can be found by searching our website by keyword or catalog number.

Find additional tips, troubleshooting help, and resources within our Nucleic Acid Quantification Support Center.

Can the Qubit kits give an indication of sample quality in nucleic acid samples?

No. The Qubit DNA and RNA kits only quantify the amount of either DNA or RNA in the sample. The Qubit fluorometer cannot take absorbance readings to provide a A260/A280 ratio or detect protein in nucleic acid samples. This can be done with the NanoDrop instrument. If your sample contains protein or other contaminants that can affect the assay, it should be further purified.

If your sample may contain both DNA and RNA, one may use either (or both) the DNA and RNA Qubit kits and compare with samples treated with either RNase or DNase to get an accurate determination of DNA or RNA, respectively.

Can I use the Quant-iT and Qubit Kits with other fluorometers?

All Quant-iT and Qubit kits are compatible with all fluorometers and microplate readers that have the appropriate light sources and filters. You won't have access to the algorithm in the Qubit fluorometer for generating the standard curve provided by the instrument, instead, you must make a few dilutions of the highest standard DNA or RNA (Standard #2) in the Qubit kits to generate a standard curve with multiple data points.

Can I use the original Quant-iT Kits with the Qubit Fluorometer?

No, we do not recommend this. Some of the dyes in the original Quant-iT kits (those NOT listed as “for use with the Qubit fluorometer”) are not compatible with the Qubit Fluorometer. In addition, the new Quant-iT kits (labeled as “for use with the Qubit Fluorometer”) have standards formulated to be compatible with the Qubit fluorometer internal algorithms for the respective assays. The Qubit Fluorometer-compatible kits are also less expensive per assay if you are processing fewer than 20 samples at a time.