By Chris Deziel, Updated March 24 2022
Mikumi/iStock/GettyImages
A sodium chloride (NaCl) solution, commonly known as saline, is essential for many medical, dental, and laboratory applications. The most widely used concentration—0.9% w/v—is isotonic with human body fluids, making it ideal for mouth rinses, eye flushes, and intravenous therapy when prepared under proper sterile conditions.
Fill a clean, graduated flask with approximately 80 % of the final volume using distilled or sterile water. For instance, to make 100 mL of solution, pour 80 mL into the flask.
For a 0.9 % (w/v) isotonic solution, weigh 9 g of non‑iodized table salt for every 100 mL of water. If you need a larger volume, scale the mass proportionally (e.g., 2.9 Tbsp for one pint).
Add the measured salt to the water and swirl gently until fully dissolved. Then top up the flask with distilled water until the final desired volume is reached.
Prepare a 1‑L solution by calculating the required mass of NaCl based on its molar mass of 58.44 g mol⁻¹.
For 1 M, weigh 58.44 g; for 0.1 M, weigh 5.84 g; for 2 M, weigh 116.88 g, and so forth.
Place 0.8 L of distilled water in a flask, add the calculated NaCl, and shake until the salt is completely dissolved.
After dissolution, add additional distilled water until the total volume reaches exactly 1 L.
For an isotonic mouthwash, boil distilled water first, then add 0.9 % (w/v) non‑iodized salt. Avoid sea or rock salt, which may introduce impurities.
Homemade saline solutions lack the sterility of laboratory‑prepared solutions and should not be used for contact‑lens soaking or ocular irrigation. For medical applications, use commercially prepared sterile saline or prepare under aseptic conditions.
