One of the most important solutions that are utilised in hospitals, microbiology laboratories, research and clinical settings is normal saline solution.
Accuracy and sterility are very important whether you are preparing bacterial suspensions, serial dilutions or using it in the medical field.
As a microbiology student, or work professional in the lab, learning how to master this procedure is a guarantee of reliable and reproducible results.
What Is Normal Saline Solution?
A Normal saline solution is a solution that contains dissolved solvents at a percentage usually 0.9 per cent (w/v) Sodium chloride.
The term 0.9% weight/volume means:
A sodium chloride solution was made by dissolving 0.9 grams of the salt in sufficient water to obtain 100 mL of solution, mostly distilled water.
The reason being that it is isotonic to human blood plasma, in other words, it has the same osmotic pressure as body fluids hence the name normal. This helps to avoid the shrinking (crenation) or bursting (hemolysis) of cells.
Normal Saline Formula and Calculations:
Standard Formula is usually: Mass of NaCl (g) = 0.9/100 x Final Volume (mL)
NB: In this procedure I’m going to prepare 100 ml of Normal saline solution.
Procedural Guide: Preparation of normal saline.
Step 1: Accurately weigh Sodium Chloride.
Weigh the necessary quantity of NaCl (in my case: 9 grams of the NaCl) using an analytical balance.
Specificity is relevant as the minor mistakes can influence the isotonicity.
Step 2: Measure 100ml of the Distilled water.
Using a volumetric flask, measure 100ml of the distilled water.
Step 3: Dissolve in NaCl with the Distilled Water.
Place the distilled water into a conical flask. Then proceed adding the measured {9 grams} of the NaCl into it.
Step 4: Mix the solution
Mix Gentle until all the Sodium Chloride dissolves into the distilled water. After every crystal has dissolved, transfer the solution into a separate bottle that is sterile. The solution is now ready to be used in the laboratory.
We have a tutorial guide on how to prepare the solution. Watch the video to improve your laboratory skills.
Conclusion
A simple but a necessary laboratory skill is preparation of normal saline solution (0.9% NaCl). The calculation may seem that difficult but measuring, necessary dissolution, adjusting of the volume and sterilisation are the factors between a good solution and a bad one.