Solutions: Part 1 – Solutions used in Clinical Laboratory and Dilution Formula
 Following the type of solutions commonly used in the clinical laboratory.
Percent solution
 This is defined as parts per 100 which represents the percent (%).
 This is independent of the molecular weight of the substance.
 This is expressed the concentration of a solute as a percent % (per hundred parts of the total solution).
 If you want to make a 5 % glucose solution, then you will add 5 grams of glucose in 100 ml of distal water.
Percent solution may be :
 Weight/weight
 The % of a solute or grams of solute per 100 grams of the final solution.
 e.g to make a 100 G of a 5% of an aqueous solution of HCl.
 Calculation = 5 % = 5/100 = 0.05
 Therefore 0.050 x 100 = 5 grams of HCL.
 Another example is:
 5 grams Na_{2}SO_{4} dissolved in 95 grams of water (roughly 95 mL). Total weight of 100 grams (solute + solvent).
 The % of a solute or grams of solute per 100 grams of the final solution.
 weight/volume: This is usually expressed as gram / 100 mL.
 To make a 10 % solution then add 10 grams of the substance to a final volume of 100 mL of liquid.
 Volume/volume:
 e.g if you want to make 50 mL of 2% HCl.
 calculation is = 0.20 x 50 = 1 mL
 Therefore add 49 mL of water to 1 mL of HCL.
 This is convenient for the composition of two liquids.
 5% of the glacial acetic acid solutions:
 5 mL of glacial acetic acid diluted with distal water to a volume of 100 mL.
 e.g if you want to make 50 mL of 2% HCl.
Molar solution

 This is defined as units of moles per liter (mol / L).
 or millimoles / millimeter (mmol / mL).
 1 Mol of a substance = gram molecular weight of that substance.
 Example make up 250 mL of a 4.8 molar solution of HCl.
 HCL molar weight = 36.5 g.
 36.5 HCL/mol x 4.8 mol HCL/L x 250/1000 mL = 43.8 g HCL
 250 mL H2O + 43.8 = 4.8 Molar solution.
 Example make up 250 mL of a 4.8 molar solution of HCl.
 This is defined as units of moles per liter (mol / L).
Normal solution

 Normality is defined as equivalent weight per liter (eq.wt / L).
 OR milliequivalent weight / milliliter (meq / mL).
 Equivalent weight = gram weight / valency.
 e.g NaCl gram weight = 58 gram and valency = 1
 58 / 1 = 58 grams equivalent weight per liter.
 Normality is defined as equivalent weight per liter (eq.wt / L).
Simple Dilution

 This is defined as the total volume desired and the amount of stock needed.
 1: 10 dilution = ratio of 1 : 9 = 1 : 10 = one part of serum + 9 parts of diluent.
 100 μL + 900 μL of saline.
 1 mL serum + 9 mL of saline.
 2 mL serum + 18 mL of saline.
Serial Dilution
 This is defined as multiple progressive dilutions ranging from a more concentrated solution to a less concentrated solution.
 Serial dilutions are useful in a small quantity of serum and to find the titer of antibodies.
 The first dilution is made just like the simple dilution.
 Now subsequent dilutions are made from each preceding dilution.
 If you want to make a serial dilution of 1: 2, 1: 4, 1: 8, 1: 16, and so on.
 The total volume is fixed, suppose is 1 mL.
 (Initial dilution factor) (next dilution factor) = final dilution factor
 1 : 2 X 1 : 2 = 1 : 4.
 Procedure
 First tube = (1 mL serum + 1 mL diluent) = 1 : 2
 Second Tube = 1 mL from from ist tube + 1 mL diluent = 1 : 4
 Third tube = 1 mL from tube 2 + 1 mL diluent = 1 : 8
 Fourth tube = 1 mL from tube 3 + 1 mL diluent = 1 : 16