Before you start
- Blank with the same buffer your sample is in.
Reagents and materials
Totals are for 12 samples (+10% extra). Per-sample amounts are in the middle column.
| Reagent | Per sample | Total |
|---|---|---|
| Sample (NanoDrop) | 1.5 µL | 1.5 µL |
| Qubit working solution (dye 1:200 in buffer) | 199 µL | 199 µL |
| Sample (Qubit)1–20 µL; adjust buffer to 200 µL | 1 µL | 1 µL |
Buffers and recipes
Absorbance conversions (A260 = 1.0, 1 cm path) per reference
| Double-stranded DNA | 50 µg/mL |
| RNA | 40 µg/mL |
| Single-stranded DNA | 33 µg/mL |
| Pure DNA A260/280 | ≈ 1.8 |
| Pure RNA A260/280 | ≈ 2.0 |
| A260/230 (both) | ≈ 2.0–2.2; low = salt, guanidine, phenol |
Equipment
- NanoDrop or other UV spectrophotometer
- Qubit fluorometer and assay tubes
Procedure
Tick steps as you go (saved in this browser). Steps with a clock have a built-in timer.
Clean pedestals
Clean the upper and lower pedestals with water and a lint-free wipe.
Blank
Load 1–2 µL of the sample buffer and blank the instrument.
Measure
Load 1–2 µL of each sample; record concentration and A260/280 and A260/230 ratios. Measure twice for low concentrations.
Qubit (if accuracy matters)
Mix dye working solution with sample to 200 µL, incubate 2 min at room temperature and read against the kit standards.
Critical points
- UV absorbance cannot tell DNA from RNA or free nucleotides; Qubit dyes are specific.
- Below about 10 ng/µL, NanoDrop readings are unreliable.
Troubleshooting
| Problem | What to check or change |
|---|---|
| Odd ratios | Re-blank, clean the pedestal, check for contaminants; re-purify if needed. |
| Readings differ between methods | Trust the dye-based value for library prep and sequencing. |
Safety
Standard laboratory care.
Further reading
- Instrument manuals (NanoDrop, Qubit).
This is a general starting-point protocol written for SolvesEverything. Follow your institution’s approved protocols, safety rules and manufacturers’ instructions, and optimise for your system. Spotted an error? Tell us.