Show your work Describe how to make 10ml of a 150 dilution f

Show your work. Describe how to make 10ml of a 1:50 dilution from a 1 times 10^12 cells/ml stock. What is the resulting cell concentration?

Solution

a) - Dilution of 1:50 means 1 part of cell stock in 49 parts of diluent (medium). For eg: If 1 mL of cell stock solution is added to 49 mL of diluent or medium, a total volume of 50 mL is obtained. It can be expressed as follows:

Volume of cell stock/volume of solution = [1 mL cell stock solution ]/[1 mL cell stock solution + 49 mL medium]

                        1 mL stock solution/ 50 mL solution = 1:50 (50 is the diltution factor)

- But here, only 10 mL total solution is required after dilution.

Formula is: Final volume/Solute volume = Dilution factor

i.e. 10 mL / Solute volume = 50

Therefore, solute volume = 10/50 =0.2 mL of cell stock solution is to be taken for dilution

- The diluent (medium) to be added is 10 mL - 0.2 mL = 9.8 mL diluent

- Thus, 0.2 mL cell stock solution is to be added to 9.8 mL of diluent to get 10 mL which is 1:50 diluted.

b) In 1 mL, there is 1 x 10¹² cells in stock solution.

To make 10 mL of 1: 50 dilution, 0.2 mL of cell stock solution is added.

In 10 mL, cell concentration is = 0.2 * 10¹² cells / 10 mL or 2 * 10¹¹ cells/ 10 mL (by cross multiplication)

In 1 mL, the cell concentration would be = 2 * 10¹¹ cells / 10 mL = 2 * 10¹⁰ cells/ mL (by cross multiplication)