A ten-fold dilution reduces the concentration of a solution ora suspension of virus by a factor of ten that is to one-tenth the originalconcentration. A series of ten-fold dilutions is described as ten-fold serialdilutions. In this manual, ten-fold serial dilutions are used in titrations of asuspension of Newcastle disease virus to establish the infectivity titre. Theyare carried out in small sterile test tubes. These tubes are usually made ofglass and it is preferable if they have fitted lids to minimize the risk ofcontamination during the dilution.
A ten-fold dilution
Step 1. | Use a micropipette to dispense 900 mL of the diluent to glass tube. |
Step 2. | Use a micropipette to transfer 100 mL of the test solution to the first well. Discard thetip. |
Step 3. | Mix by shaking by hand or using a vortex mixer. |
Step 4. | The well now contains 100 mL ofthe original test solution diluted by one tenth in a total volume of 1000 mL. |
Ten-fold serial dilutions
Step 1. | Set up the sterilized glass test tubes in a rack. Label eachtube clearly to indicate the dilution of its contents after the ten-fold serialdilution has been carried out. |
Step 2. | Use a micropipette to dispense 900 mL of the diluent to all the labeled steriletubes. |
Step 3. | Use a micropipette to transfer 100 mL of the test solution to the first tube and mix. Thisis the first ten-fold dilution. |
Step 4. | Use a micropipette with new sterile tip to carry out a secondten-fold dilution. |
Step 5. | Continue the series of ten-fold dilutions until the lasttube. |
Figure 27: Ten-fold serialdilutions
