A two-fold dilution reduces the concentration of a solution bya factor of two that is reduces the original concentration by one half. A seriesof two-fold dilutions is described as two-fold serial dilutions. In this manual,two-fold serial dilutions are carried out in small volumes in microwell plates.They are used in both the haemagglutination and haemagglutination inhibitiontests to establish titres of the test samples.
A two-fold dilution
Step 1. | Use the micropipette to dispense 25 mL of PBS diluent to the first well. |
Step 2. | Use the micropipette to transfer 25 mL of the test solution to the first well. |
Step 3. | Use the micropipette to mix by drawing up the liquid andexpelling it again. Carry out this action twice. |
Step 4. | The well now contains 25 mL ofthe original test solution diluted by one half in a total volume of 50 mL. |
Two-fold serial dilutions
Step 1. | Use the micropipette to dispense 25 mL of the PBS diluent to all the wells across a row of amicrowell plate. |
Step 2. | Use the micropipette to transfer 25 mL of the test solution to the first well and mix. Thisis the first two-fold dilution. |
Step 3. | Use the micropipette with the same tip to carry out a secondtwo-fold dilution. |
Step 4. | Continue the series of two-fold dilutions until the secondlast well of the microwell plate. The last well is used as a control well in thehaemagglutination and haemagglutination inhibition tests. |
Figure 25: Two-fold serialdilutions
