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

Quantitative expressions…..

• 1. Percentage
• a. Percentage weight by weight % w/w
• This is the number of parts of solute by weight per 100 parts solution by weight.
• Example: - 37gm%w/w HCL means each 100 gm of HCL solution contain 37gm of HCL and the rest 63 gm solvent (water)

Quantitative expressions…..

• b. Percentage weight by volume (%w/v)
• It is the number of parts of solvents by weight per 100 parts of solution by volume.
• Example:- 98 gm% w/v glucose solution means, 98gm glucose was dissolved in 100 ml solution.
• c. Percentage volume by volume % V/V
• It is the number of parts of solute by volume per 100 parts of solute.
• Example :- 70% V/V ethanol means,70ml of ethanol was mixed with 30ml of water.

Exercises -1

• How do you prepare an aqueous solution of 30gm% W/V NaOH?
• Prepare 4 liter of 20% W/V trichloroacetic acid (TCA).

Quantitative expressions…..

• 2. Parts per unit.
• This is to express the number of parts by volume or by weight of solute per given volume or weight of the solution.
• For example:- If 1m ethanol (pure) is mixed with 999 ml of water, to express the number of parts of ethanol, It can be said that ethanol solution is 1:1000
• Exercise-2
• If you are asked to prepare 1000ml of a mixture of acetic acid and methanol. If the procedure says mix 1 parts of acetic acid with 3part of methanol. How can you prepare?

Quantitative expressions…..

• B. Chemical units.
• Commonly used chemical unit to express the quantity of solutes in a given solution are:-
• Mole
• Equivalents
• Molarity
• Normality
• Molality
• 1. Mole.
• 1 mole of a give substance is its atomic weight or molecular weight expressed in gram.