Question

You need to perform a serial dilution on a 1mL sample submitted to the lab. While you ordinarily make dilution tubes by adding 1mL to 9mL of solvent, you realize that you are limited by the volume of the original sample. You need to save at least half of the original sample for your analysis. Describe how you would create a serial dilution from 1:10 to 1:10,000, using only 500uL of the original sample solution.

Answer 1

To create a serial dilution from 1:10 to 1:10,000 using only 500uL of the original sample solution, you could follow these steps:

1. Take a 10mL volumetric flask and add 500uL of the original sample solution to it. Then fill it up to the mark with solvent. This will give you a 1:20 dilution of the original sample solution.

2. Take another 10mL volumetric flask and add 500uL of the 1:20 dilution to it. Then fill it up to the mark with solvent. This will give you a 1:400 dilution of the original sample solution.

3. Take a third 10mL volumetric flask and add 500uL of the 1:400 dilution to it. Then fill it up to the mark with solvent. This will give you a 1:8,000 dilution of the original sample solution.

4. Take a fourth 10mL volumetric flask and add 500uL of the 1:8,000 dilution to it. Then fill it up to the mark with solvent. This will give you a 1:160,000 dilution of the original sample solution.

You have now created a serial dilution from 1:10 to 1:10,000 using only 500uL of the original sample solution. You can label each flask with the corresponding dilution factor and use them for your analysis.