Question

Your cell suspension is 6.3 x 10^8 cells /mL. Explain how to prepare a tube of 1 mL with cells at
2 x 10^5 cells/mL. Pipetting less than 1 μL is hard to do accurately. Do a dilution if less than 1μL

After dilution,Now that you have your tube of 1 mL with cells at 2 x 10^5/mL, explain how to add 10^4 cells to each
of 10 wells. Do you have enough cells?

Answer 1

The calculations can be made as follows:

M1V1 = M2V2

Putting values:

6.3*10⁸ * V1 = 1ml * 2*10⁵

Solving for V1: 2*10⁵ / 6.3 *10⁸ or 3.17 *10^-4 ml or 0.314 ul.

Since this small volume is difficult to pipette, it is advisable to make two dilution, first half of the original to get a 1:2 state and then adding 0.114 ul of diluent to this dilution and make up to 1ml to get the final desired sample.

Now there is 1 ml dilution containing desired amount of cells. The volume of each well is nearly 200 ul.

In order to divide it into 10 wells, the volume plated in each well must be plated with 1000/200 or 5ul of sample. This 5ul of sample will contain nearly:

(2*10⁵ / 1000) * 5 = 10³ cells.

Thus, this dilution does not have enough cells.