The main difference is in concentration of the dsDNA binding dye inside the 200x solution and in Qubit™ dsDNA HS Assay Kit. According to our measurements dye concentration in Pico488 quantification kit is two times higher compared to original Qubit™ dsDNA HS Assay Kit. This gives our customer a chance to measure even smaler concentrations on Qubit reader using Pico488 DNA quantification reagent when following the original protocol.

So there are two options to follow:

Option 1. When following original Qubit protocol provided for Q32854 kit by Invitrogen. The range of dsDNA concentration measurements in practice it is is 1 pg/μL – 10 ng/μL wich can give the UHS (ultra high sensitivity) to the experiment performed.

Option 2. When diluting the more concentrated Pico488 DNA quantification reagent 1:400 (not 1:200) and this gives doubled outcome of the experiment with the same possible range of concentrations as with Qubit™ dsDNA HS Assay Kit Q32854 kit by Invitrogen. This procedure is described step by step below:

Step 1. Prepare the 1x TE buffer by diluting the 20x TE concentrate 1:20 by deionized water. Prepare the Pico488 working solution by diluting the Pico488 DNA quantification solution 1:400 (not 1:200) with 1x TE buffer (you need 200 μL Pico488 working solution for each standard and sample). Prepare the DNA standard #2  by diluting the DNA quantification standard (100 ng/mkl) 1:10 in 1x TE buffer.

Pico488 reagent experiment with Qubit reader

Step 2. Set up two 0.5 ml tube (thin-walled and optical-transparent tube) for the standards and one tube for each sample.

Pico488 experiment with Qubit

Step 3. Prepare standards and samples for concentration measurement. For the preparation of standard #1 mix 190 mkl of Pico488 working solution and 10 mkl of 1x TE buffer in 0.5 ml tube. For the preparation of standard #2 mix 190 mkl of Pico488 working solution and 10 mkl of Standard 2 (from Step 1) in 0.5 ml tube. For the preparation of samples mix 180-199 mkl of Pico488 working solution and 1-20 mkl of user DNA sample (the total volume should be 200 μl) in 0.5 ml tube. Vortex all tubes for 2-3 seconds and incubate the tubes for 3-5 minutes at room temperature.

Vortexing the sample for dsDNA quantification measurementQubit readerQubit fluorometer

The next steps should be carried out according to the instructions to the fluorimeter. Depending on the version of the fluorimeter, the names of menu items may differ from the below (specified for Qubit 1).

Step 4.  On the Home screen of the Qubit fluorometer, you should choose Quant-It dsDNA HS (DNA High Sensitivity) as the assay type. Press "Go"

Step 5. With each preparation of the Pico488 working solution, you must calibrate the fluorimeter. Select "Run new calibration" and press "Go".

Step 6. Insert the tube containing Standard #1 into the sample chamber, close the lid, then press "Go". When the reading is complete (~3 seconds), remove Standard #1. Insert the tube containing Standard #2 into the sample chamber, close the lid, then press"Go". When the reading is complete, remove Standard #2.

Step 7. Insert the tube containing User sample into the sample chamber, close the lid, then press "Go". On the screen you will see the QF value. Calculate the concentration of the sample by the formula: Concentration of the sample = QF value x 200/samle volume.

Qubit™ Invitrogen™ Quant-iT™ PicoGreen™ are trade marks of Life technologies.