20X SSC Buffer Calculator, pH 7.0
Scale a 20X saline-sodium citrate recipe prepared with trisodium citrate dihydrate and adjusted experimentally to pH 7.0.
Select a reviewed preset and enter the final volume to prepare.
| Reagent | Formula | Amount or action |
|---|---|---|
| Sodium chlorideanhydrous | 175.3 g | |
| Trisodium citrate dihydratedihydrate | 88.2 g | |
| Hydrochloric acid | Measure the pH and adjust to pH 7.0 with HCl. Determine the required amount experimentally; do not use a predicted titrant volume. | |
| Purified water | After pH adjustment, bring the total solution volume to 1 L. Do not add 1 L of water; add water only until the total solution reaches 1 L. |
How to prepare 20X SSC pH 7.0
- Add the calculated NaCl and trisodium citrate dihydrate to approximately 70–80% of the selected final volume of purified water.
- Stir until both salts dissolve completely.
- Measure the pH and adjust to pH 7.0 with HCl. Determine the required amount experimentally.
- Bring to the selected final volume, mix thoroughly, and verify the final pH.
About This Buffer
SSC, or saline-sodium citrate, is a high-salt citrate buffer widely used in nucleic acid hybridization workflows. Different SSC dilutions are commonly used during Northern and Southern blot hybridization and washing to control ionic conditions and stringency. This calculator prepares a fixed 20X SSC stock from NaCl and trisodium citrate dihydrate, with the final pH adjusted experimentally to 7.0 using HCl.
Common questions
Which sodium citrate form does this SSC recipe use?
The 88.2 g/L reference amount corresponds to trisodium citrate dihydrate, Na₃C₆H₅O₇·2H₂O.
Why is the HCl amount not calculated?
The reviewed recipe specifies adjustment to pH 7.0 with HCl, but the required volume depends on the acid concentration and the measured titration endpoint. HCl therefore remains a nonquantitative experimental step.
How do I make 1X SSC from 20X stock?
Use a 1:20 dilution of the completed 20X stock when a protocol calls for 1X SSC.
Sources and review notes
The source for the currently selected preset appears first. Recipe quantities remain tied to the cited article location.
20X SSC pH 7.0
Source location: Recipes, 20X SSC — 87.7 g NaCl and 44.1 g trisodium citrate dihydrate per 500 mL, adjust to pH 7.0 with concentrated HCl; independent composition cross-check.
Preparation method: Source-stated quantitative composition