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
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Now, let's delve into the concepts outlined in the article:
1. Dilution:
- Dilution involves reducing the concentration of a solution or suspension. In the described case, a ten-fold dilution reduces the concentration by a factor of ten, making it one-tenth of the original.
2. Ten-Fold Serial Dilutions:
- This refers to a series of dilutions where each step reduces the concentration by a factor of ten. In the context of the article, this technique is applied to titrate a suspension of Newcastle disease virus, determining its infectivity titre accurately.
3. Titrations:
- Titrations involve measuring the concentration of a solution by reacting it with a known volume and concentration of another substance. In this case, ten-fold serial dilutions are used in titrations to establish the infectivity titre of the Newcastle disease virus.
4. Micropipette:
- A micropipette is a precision instrument used for accurately measuring and transferring small volumes of liquids. It is employed in both the ten-fold dilution and ten-fold serial dilutions steps described in the article.
5. Sterile Techniques:
- Maintaining sterility is crucial in microbiological work to prevent contamination. The use of small sterile test tubes, sterile tips for micropipettes, and the setup of sterilized glass test tubes in a rack illustrate the importance of sterile techniques in this process.
6. Vortex Mixer:
- A vortex mixer is a device used to mix small vials of liquid by creating a vortex, ensuring thorough and consistent mixing. It is mentioned in the article as a method to mix the contents of the test tubes during the dilution process.
7. Glass Test Tubes:
- Glass test tubes are utilized for conducting the dilutions. They are preferred for their transparency and inertness. Fitted lids are recommended to minimize the risk of contamination.
8. Diluent:
- The diluent is the solution used to dilute the original test solution. In the provided steps, 900 mL of the diluent is dispensed into the glass tube before transferring 100 mL of the test solution, initiating the dilution process.
Understanding these concepts and their practical application is essential for anyone engaged in virology research, ensuring accurate and reliable results in experiments involving viral concentrations and infectivity titrations.
