5 M NaCl Solution Recipe
For 1 L of 5 M NaCl, use 292.2 g of sodium chloride: 5 mol/L × 1 L × 58.44 g/mol = 292.2 g.
How to prepare 1 L of 5 M NaCl
- Add approximately 800 mL of ultrapure or deionized water to a suitable vessel.
- Gradually add 292.2 g of sodium chloride while stirring.
- Continue stirring until the sodium chloride has dissolved completely.
- Add ultrapure or deionized water until the final total volume is 1.00 L.
- Mix the solution thoroughly.
- Sterilize the solution if required for the intended application.
- Label the container with the solution name, concentration, preparation date, and any applicable storage or sterility information.
Note: Bring the solution to its final volume after the NaCl has dissolved. Do not add 292.2 g of NaCl directly to 1 L of water.
Scaled quantities
| Final volume | NaCl required |
|---|---|
| 100 mL | 29.22 g |
| 250 mL | 73.05 g |
| 500 mL | 146.1 g |
| 1 L | 292.2 g |
Concentration and use
A 5 M NaCl solution is equivalent to 29.22% (w/v), meaning it contains 29.22 g of NaCl per 100 mL of final solution. Sodium chloride is not a pH buffer by itself; it is commonly used to adjust ionic strength or as a component of laboratory buffers and stock solutions.
What does NaCl do in laboratory buffers?
Sodium chloride (NaCl) is primarily added to laboratory buffers to regulate ionic strength and osmotic balance. Upon dissolution, NaCl completely dissociates into Na+ and Cl- ions. These free ions form counter-ion shields around charged biomolecules, modulating Debye screening lengths and dictating electrostatic attraction or repulsion.
In biochemical workflows, controlling ionic strength preserves the native tertiary structure and solubility of proteins, maintains nucleic acid duplex stability, and stabilizes lipid membranes. Consequently, NaCl is a foundational component of standard biological buffers, including PBS, TBS, SSC, and SSPE.
Depending on the application, NaCl concentrations are tailored to modulate macromolecular binding kinetics, drive hydrophobic interactions during precipitation/purification, or optimize stringency during hybridization and wash steps.
Note on pH: NaCl is a neutral salt and provides no buffering capacity. Target pH is established and maintained by dedicated buffering pairs within the solution, such as phosphate in PBS, Tris in TBS, or citrate in SSC.