Preparation of normal saline solution


Normal Saline Solution (NSS) is commonly used in various laboratory procedures like in the preparation of Red cells Suspension for the crossmatch, for preparing dilutions of Reagents, for stool examinations, to make the dilutions in serological tests, diagnostic tests etc.

There are commercially prepared Normal saline solution available in the market but it can easily be prepared manually in the laboratory whenever required. The normal saline solution is simply the 0.85% Sodium chloride (NaCl) solution which can be prepared in the laboratory by dissolving the calculated amount of Sodium chloride crystals in the required quantity of Distilled water.

The Normal saline solution is prepared as follows……


A normal saline solution is the 0.85% sodium chloride solution.

That means 0.85 gm of sodium chloride in 100 ml distilled water.

For preparing 1 L normal saline solution we require,

W1 / V1 = W2 / V2

W1 = Required quantity of sodium chloride for 100 ml NS = 0.85 gm

V1 = Required volume for 0.85 gm sodium chloride to make NS = 100 ml

W2 = Required Quantity of Sodium chloride to make the desired quantity of Normal Saline solution

V2 = 1000 ml (or desired quantity of Normal saline to be prepared)

0.85 gm / 100 ml = W2 gm / 1000 ml

0.85 gm × 1000 ml = W2 × 100 ml

W2 = 0.85 × 1000 ml / 100 ml

W2 = 8.5 gm