Chapter- 4 : Reagents (solution) used in clinical laboratories

Dilution of solution

• Dilution is the process by which the concentration of or activity of a given solution is decreased by the addition of solvent.
• A dilution represents the ratio of the concentrated or stock material of the total final volume of a solution. i.e Dilutions are usually expressed as 1 unit of the final solution.
• Adding a diluents such as water or saline, which contains none of the material being diluted, is used to do this.
• Dilution has two parts: diluents and solute.

Dilution …

• Dilution is used to prepare
• Working solution from stock solution
• Measurable concentration of a sample
• Whenever a solution is diluted, it is volume is increased and its concentration decreased, but the total amount of solute remains unchanged.
• The following equation is used to determine the volume (V2) needed to dilute a given volume of (V1) of solution of known concentration (C1) to the desired lesser concentration (C2)
• C1 x V1 = C2 x V2

Dilution …

• Example: to make 45 ml of 30% solution from 70% solution
• C2= 30%
• V2= 45ml
• C1= 70%
• V1= C2 x V2
• C1
• V1= 30 x 45 = 19.3ml
• 70
• There fore 19.3ml of 70% solution must be diluted with 25.7ml of distilled to obtain 45ml of 30%solution.

Methods of dilution

• A. Simple dilution
• A general process of preparing less concentration solutions from a solution of greater concentration.
• E.g.,
• if you want to prepare 1:10 dilution
• Take 1 ml solute
• Take 9 ml of solvent
• Then mix

Methods of dilution …

• B. Serial dilution
• It is defined as multiple progressive dilutions ranging from more concentrated solutions to less concentrated solutions.
• Example ???