2X RNA loading dye (formamide) recipe
A formamide loading dye that denatures RNA for gels: 95% formamide, 18 mM EDTA, 0.025% SDS, 0.025% bromophenol blue and xylene cyanol.
🧮 Volume calculator
| Component | Amount | Final concentration (1X) |
|---|---|---|
| Deionised formamide | 950 µL | 95% |
| 0.5 M EDTA (pH 8.0) | 36 µL | 18 mM |
| 10% SDS | 2.5 µL | 0.025% |
| Bromophenol blue | 0.25 mg | 0.025% |
| Xylene cyanol FF | 0.25 mg | 0.025% |
| Water (distilled) | to final volume |
Steps
- Mix all components and make up to volume with RNase-free water.
- Aliquot and store at −20 °C.
- Mix 1:1 with RNA, heat at 65–70 °C for 5–10 min, chill on ice and load.
⚠ Safety Formamide is a reproductive toxin — handle in a fume hood with gloves.
FAQ
Can I use DNA loading dye for RNA?
For a quick check on a native gel, yes; accurate sizing needs a denaturing dye like this.
This is a widely used standard composition. Amounts depend on the hydrate form and purity of your reagents — check the formula weight (FW) on the bottle and follow your institution's safety rules and the manufacturers' instructions.